CN117881958A

CN117881958A - Second harmonic generation for critical dimension metrology

Info

Publication number: CN117881958A
Application number: CN202280049044.6A
Authority: CN
Inventors: 大卫·L·阿德勒
Original assignee: Femtometrics Inc
Current assignee: Femtometrics Inc
Priority date: 2021-05-12
Filing date: 2022-05-12
Publication date: 2024-04-12

Abstract

The disclosed systems and methods use second harmonic generation of light to monitor the manufacturing process to discover variations that may affect the performance or yield of the produced devices and/or to determine critical dimensions of the produced devices.

Description

Second harmonic generation for critical dimension metrology

Cross reference

The present application claims priority from U.S. patent provisional application 63/187868 entitled "second harmonic generation for critical dimension metering" filed on day 5 and 12 of 2021 and U.S. patent provisional application 63/188054 entitled "second harmonic generation for critical dimension metering" filed on day 13 of 2021. The entire contents of each of the above applications are incorporated herein by reference. U.S. patent 10,591,525 to koldiev et al, 3/17/2020, entitled "wafer metrology technology" (which is incorporated in the appendix of the provisional application cited above) is also incorporated herein by reference in its entirety. The text and figures from us patent 10,591,525 are additionally reproduced herein.

Background

Technical Field

The present application relates generally to systems and methods for sizing.

Prior Art

Second harmonic generation is a nonlinear optical effect that involves converting light having one frequency into light twice that frequency when scattered from some types of materials, structures, and geometries. Second harmonic generation can be particularly strong at interfaces and imperfections that disrupt the symmetry of the system. This procedure can be considered as combining two photons of energy E of the incident radiation to produce a single photon of energy 2E (i.e., to produce light at twice the frequency (2ω) or half the wavelength).

Scientific research studies in which SHG technology has been employed are provided by "Optical Second-Harmonic Generation from Semiconductor Surfaces" by t.f. heinz et al, edited by a.c. tam, j.l.cole and w.c. Stwaley (U.S. physical institute, new York, 1988) at page 452, published in Laser Science III. As commented, SHG procedures do not occur within a bulk of material that exhibits a center of symmetry (i.e., in inverted or centrosymmetric materials). For these materials, the SHG process is only evident at the surface and/or interface where the inverse symmetry of the bulk material is broken. Thus, the SHG procedure provides unique sensitivity to surface and interface properties.

The SHG effect is well known and described in U.S. Pat. No. 5,294,289 to Heinz et al. Other methods or "tools" that may be employed are also described in each of U.S. patent nos. 5,557,409, 6,795,175, 6,781,686, 6,788,405, 6,819,844, 6,882,414 and 7,304,305 to Downer et al, 6,856,159 to Tolk et al, and 7,158,284 to Alles et al. However, the teachings of these patents appear to have not overcome some of the major obstacles to employing SHG as the established technology for use in semiconductor fabrication and metrology.

Disclosure of Invention

Sizing using second harmonic generation

The systems and methods described herein relate to monitoring semiconductor device fabrication using second harmonic generation. The change in the second harmonic generation of light may be used to monitor changes in the geometry or material properties of the semiconductor device (e.g., as it is being produced in-line with a production line, etc.), and/or changes in the fabrication process. Second harmonic generation may also be used to determine the critical dimensions of a semiconductor structure, device, portion of a device, or any combination thereof.

A Second Harmonic Generation (SHG) system for determining Critical Dimensions (CD), referred to herein as a SHG-CD, may illuminate a sample and use light generated by the second harmonic emitted by the device to determine the physical structure (e.g., shape and/or size) of the device and/or monitor changes in such features. An SHG-CD system may use light emitted by devices produced in a production line to monitor the quality and stability of the production process and possibly improve the yield and/or performance of the produced devices. The devices measured by the SHG-CD system may or may not have been completed and the changes may be unplanned changes (e.g., changes associated with a process tool, changes associated with degradation, environmental changes, failures, changes in consumables used by the process tool, or any combination of these or other possible factors).

In addition to or as an alternative to monitoring changes in physical characteristics (e.g., shape and/or size) of the device or portions thereof and thus monitoring production, an SHG-CD system may provide a feedback signal, feedback data, or information that may be used to control the production steps of the device. In some cases, a feedback signal, feedback data or information may be used to control the production step of producing the monitored sample. The SHG-CD system may be included in a sample evaluation step and may provide a feedback signal or feedback data to a step preceding the evaluation step (e.g., for the benefit of another device(s) or wafer, etc. to be subsequently manufactured). For example, this previous step may include a lithography, etching, deposition step, or other possible manufacturing step. In some embodiments, the SHG-CD may provide a feed-forward signal, feed-forward data, or feed-forward information that may be used to control a production step after a monitoring step or sample measurement. In some such implementations, subsequent or downstream steps may be adjusted based at least in part on the feedforward signal, feedforward data, and/or feedforward information provided by the SHG-CD, for example, to adjust or correct for manufacturing process variations detected by the SHG-CD system.

An SHG-CD system directs light, such as pulsed light (e.g., pulsed laser light), onto a sample, such as a silicon wafer comprising semiconductor devices or partially structured semiconductor devices. SHG-CD can be used to monitor a sample at some point in the semiconductor manufacturing process by directing light toward the sample and detecting the resulting SHG light (also known as the SHG signal). The pulses of incident light may generate light at a second harmonic (or half wavelength) of the incident light, sometimes referred to as a Second Harmonic Generation (SHG) signal and/or SHG light. One or more detectors may be used to measure the SHG signal. The detectors may be configured to measure one or more of intensity, angular distribution, or polarization of the SHG signal by generating a detected SHG signal (e.g., an electronic signal), or any combination thereof. In some cases, the detected SHG signal may be proportional to the intensity of SHG light incident on the detector (e.g., on an optoelectronic sensor of the detector). Additionally, the incident light pulse may be adjusted to improve (e.g., increase) the SHG signal from the sample, such as by selecting polarization, wavelength, or intensity. Additionally or alternatively, the orientation of the sample may be adjusted, such as by rotating the sample relative to the scattering plane of light.

In some cases, the sample may be prepared for second harmonic generation measurements by exposure to additional light (e.g., an auxiliary beam of light or illumination) or charge. For example, the region of the sample from which SHG light is emitted may be optically pumped by directing auxiliary illumination, such as an auxiliary beam of light, onto the region. The auxiliary light beam, which may be referred to herein as a pump beam, may have the same or a different wavelength than the main light beam incident on the sample (the pulses used to generate the SHG signal). For example, the charge may come from a corona discharge.

The signal may be monitored for changes (e.g., changes associated with intensity, polarization, spatial distribution, etc.) in the SHG signal that may be indicative of changes in the production of the semiconductor device (e.g., changes in one or more processes prior to metrology). In some cases, an SHG signal may be modified (e.g., by one or more optical components) and the modified SHG signal may be indicative of a change in production of a sample or device. In some cases, a detected SHG signal may be modified (e.g., by an electronic processor) and the modified detected SHG signal may be indicative of a change in production of a sample or device.

Such variations in the production of semiconductor devices may produce variations in device geometry, such as variations in device dimensions (e.g., width, length, height, thickness), such as the width of a transistor feature, or alignment and/or spacing between features. Such variations in geometric features may also include variations in shape. In some cases, the SHG signal and/or the detected SHG signal may be processed (in the optical or electronic domain) to make changes in the SHG signal and/or the detected SHG signal more pronounced. In some embodiments, the SHG signal may be used to alert manufacturing personnel of a potential problem with production or to send a signal to one or more in-line manufacturing tools. In some implementations, the SHG signal or detected SHG signal may be used to provide feedback to production equipment early in or upstream of the production process, e.g., potentially to improve device yield or performance. In some embodiments, the SHG signal or detected SHG signal may be used to provide feed forward to subsequent or downstream steps of the production process to adjust or correct for previous changes.

The SHG signal may be used to determine or provide information about the geometry or electronic structure of features of a manufactured device. The device may be a finished product or at some early stage of production. In some implementations, for example, the SHG signal or detected SHG signal may be compared to a database of (e.g., geometric) features to determine the structure of the device (e.g., geometric) features. In some cases, the SHG signal or detected SHG signal may be compared to a database of (e.g., material properties) characteristics to determine a material property (e.g., electronic structure) of the device. In some examples, the SHG signal and/or the detected SHG signal may be modified and the modified SHG signal, the modified detected SHG signal, and/or data based on any of these may be compared to other data (e.g., previously measured/processed SHG signal or detected SHG signal, modified detected SHG signal, and/or other processed signal). The SHG signal may also be used to calculate a structure based on a priori knowledge of the structure (e.g., geometry). A database of (e.g., geometric and/or material property) features may include data calculated and/or measured prior to measurement of the device to facilitate rapid identification of the device structure. These results (e.g., determined features) may also be used to alert a manufacturer to process variations, communicate with an in-line manufacturing tool, and/or provide feedback or feed-forward to adjust the semiconductor device fabrication process as previously described. In various designs, a primary pulsed laser beam impinges a spot on the surface of a completed or partially formed integrated circuit (e.g., a silicon integrated circuit). The pulses may generate light of the second harmonic of the main beam via interaction with the completed or partially formed integrated circuit (e.g., a completed or partially formed device in the integrated circuit). The SHG signal is measured using one or more detectors. The measurement may include the intensity, angular distribution, polarization, or any combination thereof of the SHG light. The sample may also be rotated to make multiple measurements (e.g., corresponding to different angles of incidence and/or SHG light emitted in different directions), and/or the wavelength and/or polarization or other optical properties of the primary beam may also be changed.

The processed or unprocessed detected SHG signal may be compared to a signal generated by a computer simulation that simulates an SHG using a model (e.g., a simulated detected SHG signal or a simulated modified detected SHG signal). The model may contain geometric information (such as one or more sizes or shapes) from the sample. In some examples, the geometric information (e.g., reference geometric information) may include at least two dimensions. For example, the geometric information may include any combination of the height, width, or length of a feature and may potentially include pitch. Geometric information may also include shapes, for example, shapes may include angles, orientations, smoothness, roughness, or other features or characteristics.

The model may be empirically generated from measurements or calculated, or a combination of both. The model may be used to evaluate the SHG optical signal or the processed SHG optical signal to determine a structure (e.g., geometry) or a change in structure (e.g., geometry) of the device on the sample.

The result of the comparison may be used to monitor a manufacturing process. In some examples, if the comparison indicates a significant change in device structure (e.g., an unintended change in a geometric feature), the process may be temporarily suspended until the problem is resolved. Additionally or alternatively, the results of the comparison may be used to help develop new device structures or programs for the manufacture of a device.

In some embodiments, in addition to or in lieu of the detector, an SHG-CD system may include at least one spectrometer configured to detect SHG signals received from a sample and measure the intensities of the plurality of SHG signals or the relative intensities of the SHG signals to determine characteristics (e.g., geometry, material structure, critical dimensions) of the sample. Likewise, different detectors or sensors with different spectral responses or filters with different wavelength spectra may be used to sample different wavelengths and possibly obtain different intensity values for detecting different wavelengths. Having information about the relative intensities of the different wavelengths can help determine changes in the SHG output and changes in the device or sample.

In various embodiments described herein, a system for characterizing a sample using second harmonic generation includes: at least one light source configured to direct a beam of light onto a sample to generate a Second Harmonic Generation (SHG) signal; an optical detection system comprising at least one optical detector configured to receive the SHG signal emitted from the sample and to generate a detected SHG signal; one or more hardware processors (e.g., hardware processors, processing electronics, microprocessors, and the like) in communication with the optical detection system, the one or more hardware processors configured to receive at least one detected SHG signal and determine a geometric feature of the sample or a change in the geometric feature of the sample based on the at least one detected SHG signal.

In other implementations described herein, a method of determining a size of a sample using second harmonic generation includes: receiving a first SHG signal; changing at least one parameter of the light beam of at least one light source or an optical detection system; receiving a second SHG signal after the variation of the at least one parameter; the geometry of the feature of the sample is determined based on the first SHG signal, the second SHG signal, and a mapping of a SHG signal to the geometry of the feature of the sample.

In other embodiments described herein, a system for characterizing a sample using second harmonic generation includes: at least one light source configured to direct a beam of light onto a sample to generate a Second Harmonic Generation (SHG) signal; an optical detection system comprising at least one detector configured to receive the SHG signal emitted from the sample and to generate a detected SHG signal; one or more hardware processors in communication with the optical detection system, the one or more hardware processors configured to receive at least one first detected SHG signal, determine a change in a characteristic of the first detected SHG signal or the sample, and output an indication of the change.

In other embodiments described herein, a system for characterizing a sample using second harmonic generation includes: at least one light source configured to direct a beam of light onto the sample to generate a Second Harmonic Generation (SHG) signal; an optical detection system comprising at least one detector configured to receive the SHG signal emitted from the sample and to generate a detected SHG signal; one or more hardware processors in communication with the optical detection system, the one or more hardware processors configured to: receiving a first detected SHG signal from the optical detection system, the first detected SHG signal collected by the at least one detector at a first angle relative to a characteristic of the sample; receiving a second detected SHG signal from the optical detection system, the second detected SHG signal collected by the at least one detector at a second angle relative to the feature of the sample, the second angle different from the first angle; and determining the size of the feature of the sample based on the first detected SHG signal, the second detected SHG signal, and a mapping of a detected SHG signal to the size of the feature of the sample.

In other embodiments described herein, a system for characterizing a sample using second harmonic generation includes: at least one light source configured to direct a beam of light onto a sample to generate a Second Harmonic Generation (SHG) signal; an optical detection system comprising at least one detector configured to receive an SHG signal from the sample and to generate a detected SHG signal; one or more hardware processors in communication with the optical detection system, the one or more hardware processors configured to receive the first detected SHG signal, determine a change in the detected first SHG signal, and output an indication of the change.

In various embodiments, the detected SHG signal is processed. For example, the detected SHG signal may be transformed by one or more calculations, etc. The detected SHG signal of this process (or modification) may be used, for example, to determine geometric features (e.g., dimensions) or data regarding or based on the geometry of a partially or fully formed device or portion thereof, to monitor changes thereto, etc., and/or to monitor changes in the fabrication process, etc.

In various implementations, the processed or unprocessed detected SHG signal or values obtained therefrom may be compared to a reference, such as a reference value or reference signal (simulated, empirically measured, or a combination thereof), for example, to determine a change in geometry or geometric feature (e.g., dimension) of a partially or fully formed device, a change thereof, a change in a fabrication process, or any combination thereof.

In various implementations, the processed or unprocessed detected SHG signal or the modified detected SHG signal, or a value obtained therefrom, may be compared to a previously measured detected SHG signal or a previously generated modified detected SHG (e.g., stored in a memory of the system), to determine, for example, a change in a geometry or geometric feature (e.g., size) of the partially or fully formed device, a change thereof, a change in a fabrication process, or any combination thereof. In some cases, the change in geometry or geometric feature may include a change in geometry or geometric feature as compared to a previously measured sample (e.g., a sample generated by the same procedure used to generate the sample from which the detected SHG signal was obtained).

As discussed above, the SHG signal may depend on the geometry or geometric features (e.g., dimensions) of the partially or fully formed device or portion thereof. Furthermore, the SHG signal may depend on, for example, material properties (such as, for example, electronic properties) at the interface of or within the sample under test. Additional techniques that facilitate obtaining such material (e.g., electronic) properties or characteristics of a sample to be measured from a measured SHG signal may be used in combination with other techniques such as those described herein that relate to obtaining SHG signals that depend on the geometry of a partially or fully formed device. Likewise, in various embodiments described herein, the SHG system may be configured to obtain SHG signals that provide information about the geometry or geometry change of a partially or fully formed device, as well as information about the material properties (such as electronic properties) of such devices or portions thereof.

SHG-based optical metrology

Part I

An SHG metrology tool is described in which electrons in a layered semiconductor substrate are excited differently for second harmonic generation purposes by each of a pump light source and a probe light source having different power characteristics. For such a method, a metrology characterization tool has an "extra" integrated light source (e.g., a UV flash or laser) that operates as a "pump" to induce potential differences across heterogeneous interfaces in the layered semiconductor device template, and a short or ultra-short pulsed laser (e.g., a femtosecond solid-state laser) that operates as a "probe" light source. The utility results from using two different sources in conjunction or combination with each other for different purposes (via various time-shifting and/or variable pump energy methods as further described), such as distinguished from a single laser SHG or a dual or multiple laser SFG system.

In one approach, a pump is used as a pre-excitation light source to allow for a reduction in the total characterization time of some materials. In many such embodiments, the time dependent electric field is not generated primarily by a probe/probing laser. In a variation of this approach, a pump is used to UV flash the entire wafer and then rasterize or otherwise scan the entire wafer or some portion thereof using a probing laser, taking a minimum probing time per spot (e.g., scanning as fast as a hardware movable laser). In this regard, the options include column-by-column scanning with a step along the (scan) line by wafer shift. Another approach may employ wafer rotation and scanning along a radius.

In another variation, the pump allows for rapid charging of the material interface at a sample site, followed by probing for attenuation of the charged interface in conjunction with the rapid blocking and/or optical retardation method described further in section II of U.S. provisional application No. 61/980,860 entitled "CHARGE DECAY MEASUREMENT SYSTEMS AND METHODS," filed on 4 months 17, entitled "WAFER METROLOGY TECHNOLOGIES". Regardless, in various embodiments, the purpose of the pump for pre-excitation is to inject charge carriers into the dielectric, for example, in an amount sufficient to affect the interface.

In another approach, a pump light is employed as a post-excitation light source to affect the SHG signal that has been generated by the probe laser at a sample site. Yet another approach uses comparison/contrast of SHG signals generated by the probe before and after the application of pump laser energy. By detecting the sample before pumping and measuring the SHG response, then applying radiation from the pump light source and thereafter re-detecting the difference in SHG response before and after pumping can be used to determine additional material properties such as trap density in the material dielectric.

In the various methods discussed herein, a timing difference (i.e., in terms of pre-excitation and/or post-excitation by the pump source in connection with detecting laser use) is employed to deliver an interrogation profile that indicates further information about the material interface.

In various approaches, a pump source and a probe source are used in combination to provide an SHG signal that is used to determine the threshold injection carrier energy. Specifically, the frequency of a tunable pump laser is ramped up when probing with a probe laser. At a particular frequency, the SHG signal exhibits an inflection point (or a discontinuous region). The value corresponding to the pump frequency at the inflection point (or the discontinuity region) may be related to the threshold injection carrier energy.

Embodiments of the target pump and probe system also provide specific hardware-based advantage possibilities. In the example where the pump is a flash lamp, a highly correlated cost savings may be achieved over a 2-laser system. Whether provided as a flash or a second laser, the combination of pump and probe as contemplated herein may also reduce optical damage to the substrate to be interrogated, as too strong illumination would degrade the dielectric and even the substrate if a threshold average power is exceeded. The threshold average power that causes optical damage to the substrate can be determined by experimental calibration studies.

To understand the latter possibility of incorporating target hardware, some background is provided. That is, both pump energy and probe energy can be used alone to generate an SHG signal using this hardware. While the pump source and probe source do not need to operate in combination to generate the SHG signal, in the target method the relevant material properties are primarily derived from the SHG intensity generated by the probe, as the pump will typically not have peak power to properly drive the buried interface SHG. The time dependent SHG intensity profile will change based on the distribution of charge carriers across an interface (e.g., between the dielectric and the substrate). The time required to inject carriers across an interface (e.g., between the dielectric and a semiconductor substrate) depends on the average power calibrated across the sample. In some embodiments, the probe may separately enable carrier injection across an interface between the dielectric and the substrate. In such implementations, due to the inability to decouple the average power from the peak power, the time required to reach a target average power that allows carrier injection across an interface between the dielectric and the substrate without exceeding the optical damage threshold of a material may be greater than in implementations using a combination of pumps and probes. By using a high average power but low peak power light source as a pump to inject carriers across an interface between the dielectric and the substrate prior to probing, a time savings of increased average power can be produced without the potential damaging complications that can be caused by high peak power at that average power.

Thus, the target probe is typically a higher peak power source with a low average power, as compared to the pump. In other words, the detection laser is typically relatively very weak. In one aspect, this allows for minimal disturbance to the natural electric field present at the substrate interface to generate an initial time independent signal.

At higher average power but low peak power, the pump induces an electric field (E) by causing charge carriers to undergo an energy step rise at or across the material interface. By using a relatively high average power source as a pump and by rapidly "charging" the interface by giving all available electrons at least enough energy to jump into the dielectric, a situation is created in which a high peak power (providing a high SHG conversion rate) but low average power (due to the short pulse duration and limited number of such pulses) detection laser can rapidly interrogate the surface to provide time-independent SHG signal data.

Thus, in various embodiments described herein, a reduction in the time required for a probe laser to move electrons to higher energy levels or across the interface may be achieved, which may allow for faster evaluation of a steady state SHG signal and/or charge carrier time dynamic measurement. This approach also allows to separate the effect of the SHG probe from its own effect on the electric field at the substrate interface, which also allows to speed up or ignore the time dependence in the SHG procedure and allows to acquire time independent SHG data faster on at least part of the acquired signal from the probe beam. As such, another aspect allows faster and/or more accurate determination of threshold energy for carrier injection into an interface (e.g., an interface between a semiconductor and a dielectric), as well as (faster throughput) in a line tool environment. Whatever the context, the provided availability time reduction may advantageously facilitate high throughput testing in any kind of online metrology tool in the semiconductor industry. For example, a time-dependent curve is generated for a pre-existing application using SHG technology on a device (10 nm device layer/25 nm BOX SOI) that includes a 25nm buried oxide layer under a 10nm silicon-on-insulator, requiring 6 seconds to 12+ seconds for each point. Using pre-excitation as described herein, a time dependence can be created in less than 1 second to wait for material and pump/probe power. This advancement will achieve more than 10 times the surface area covered on a wafer within a wafer/line given the available time, or equivalent reliability within 10% of the time. And while such numbers will vary based on material, layer thickness, and specific pump/detection power and wavelength, they should be heuristic.

All inventive embodiments described herein include the following: methodologies associated with the methods described herein, alone or in combination with component components or features from the present application, the referenced patent applications incorporated herein by reference, and different portions of any of the documents incorporated herein by reference; hardware to implement methodology; a production system incorporating hardware and products thereof, including products produced by programming.

Part II

To date, SHG-based metrology tools have had limited adoption. This is believed to be accomplished because the existing system cannot distinguish between the detected interface properties. In other words, while existing SHG techniques provide a way to determine the location and presence of interfacial electroactive anomalies, these methods rely on relative measurements and are virtually incapable of parsing and/or quantifying detected contaminants between electroactive anomaly types (e.g., gettering contaminants such as copper and bond voids).

However, the target system and method can capture quantitative information in different ways to make the decisions required for this activity. In such systems and methods, after a wafer sample is charged with optical electromagnetic radiation (either with a pulsed laser at a specific location or with a flash lamp or other electromagnetic energy source or light source or otherwise), a plurality of measurements are made to monitor the instantaneous electric field decay associated with the heterogeneous interface controlling the decay period.

Using decay curve data generated and characterized at multiple points, spectral parameters of an anomaly or problem at a sample site can be determined such that differentiation and/or quantification of defect types or contaminants is possible. In general, attenuation dependent data is collected and used to provide a system by which charge carrier lifetime (lifetime), trap energy, and/or trapped charge density can be determined so that defects and contaminants can be mutually distinguished or parsed for species discrimination (if a contaminant is detected) and/or for contaminant quantification (if detected).

This activity is determined on a bit-by-bit basis using a selected methodology that is typically repeated to scan the entire wafer or other sample or region of material thereof. With respect to the computer processing required to achieve this determination, it may occur "in real time" (i.e., during scanning, the output results do not have any substantial delay) or via post-processing. However, in various embodiments, the control software may run without hysteresis in order to provide accurate system timing to obtain target data according to the methodology described below.

Sample material charging is monitored in conjunction with SHG signal generation, as needed. In this case, the information obtained via this signal can be used for material analysis and decision making.

In any case, a system embodiment may include a system having a power supply of at least 10 ² Seconds to picoseconds (10) ^-12 Seconds) of the fast shutter. Such systems may be used to self-surface and embed thin film materials after introducing short barrier time intervalsThe Tibetan interface monitors SHG signal generation at a sample site. This time interval may be timed to monitor the field decay of interest.

The target system may also include a light delay. The delay line may be an optical fiber-based device, particularly if coupled to dispersion compensating and polarization controlling optics. Alternatively, the delay line may be mirror based and similar to the examples in U.S. patent No. 6,147,799 to MacDonald, no. 6,356,377 to Bishop et al, or No. 6,751,374 to Wu et al. In any case, a delay is used in the system to allow for the delay in picoseconds (10 ^-12 Second) to femtosecond (10 ^-15 Second) and possibly attosecond (10) ^-18 Second) range of laser interrogation of materials. This interrogation may be useful in detecting multiple charge decay-dependent data points along a single decay curve.

The target method includes a method involving measuring an SHG signal for decay data points acquired after a continuous charging event. The conditions used to obtain a SHG signal may be different at each charging event. Furthermore, the time interval between successive charging events may be different. In this approach, multiple data points (at least two but typically three or more) may be associated and represented as a single composite decay curve. Another approach employs minimally destructive (i.e., the radiation used to generate the SHG signal does not significantly recharge the material) SHG signal interrogation events after a single charging event.

Yet another method for determining transient charge decay involves measuring the discharge current from the sample material (more precisely, its structure charged by optical radiation). The time dependence (dynamics) of this signal can then be handled in the same way as in the case of SHG sensing. Further, as described above, this sensing may be accomplished over a span of decay time intervals and/or over a number of decay time intervals after charging to a given level. In any case, the specific hardware of the electrode for this purpose is detailed below.

With respect to charge or charge level, this can reach a significant saturation point when the charge dynamics are observed at standard linear times or for a pair of time scales. As described above, the target methodology observes, records and analyzes charging dynamics as needed, as this can yield important information.

For continuous charging/interrogation events, if the initial state of charge of a sample is measured and the saturation level is not far from the initial state of charge, the system may omit further or subsequent characterization. In this context, what may be considered "near" may mean about a 1% to about 10% charge increase relative to the initial state of charge to be determined by learning when the target tool is used within a given sampling time.

In other words, the term "saturation" is a relative term. Using a linear time scale, the material will soon saturate. However, if the SHG signal strength associated with charging is observed within a logarithmic scale of 10 seconds to 100 seconds, then the later stages of saturation can be observed to occur with a different time constant and be relatively more gradual or time consuming. Thus, while examples of methodologies provided herein discuss charging to saturation, delays and other timings may be considered to occur relative to significant saturation. Instead of waiting for the full amount of 100% saturation, which may be an unnecessary time to reach, the instrument may delay until significant saturation is reached or significant parameters may be extracted, independent of how long it takes to fully saturate.

Further, it should be appreciated that as the monitored charge or charge level approaches saturation (i.e., in connection with SHG monitoring), the target methods and systems may operate below the saturated charge and/or recharge level (as discussed above) while still producing meaningful decay curve information. However, without this measurement, when approximate saturation is a known parameter (e.g., by experience with a target tool of a given material), charge to saturation is employed as the target level.

Notably, various interface material properties can also be determined using laser beam blocking or retardation as further described in section III of U.S. provisional application No. 61/980,860 entitled "temp tube-CONTROLLED METROLOGY," filed on publication No. 2014, 4, 17, which is incorporated herein by reference in its entirety. The introduction of a DC bias across the sample being tested may also aid in the analysis of the material. A DC bias is used to actively change the initial charge distribution at the interface before any effect is produced by the photo-induced voltage. To this end, the sample under test may be mounted atop a conductive chuck that may serve as a ground for DC biasing across the sample using the sample top surface probe. Other ways of introducing an induced voltage bias are also possible without the use of a surface probe, as further described in section IV of U.S. provisional application No. 61/980,860 entitled "FIELD-BIASED SHG METROLOGY," filed on 4 months 17, 2014, entitled "WAFER METROLOGY TECHNOLOGIES".

Furthermore, the target system may use a secondary light source in addition to the primary laser involved in the blocking type analysis for charge decay determination. Such a set of sources may be employed as a radiation pump/probe combination as further described in U.S. provisional application No. 61/980,860 entitled "PUMP AND PROBE TYPE SHG METROLOGY" filed on date 17 at 2014, 4, entitled "WAFER METROLOGY TECHNOLOGIES".

Part III

Various field bias (e.g., magnetic field bias, DC bias, and/or voltage bias induced by an AC field alone, with a capacitive coupling and/or a varying magnetic field) SHG-based systems and methods of using the same are described. These field biases are processed sequentially, which may be used independently and/or in a combined system. The embodiments described herein include the following: methodology associated with the methods described herein; hardware to implement methodology; a production system incorporating hardware and products thereof, including products produced by programming.

Bias of magnetic field

A static or varying magnetic field applied to the sample will cause a second order optical polarizability tensor of a material to change. Thus, a magnetic field may be used to increase the SHG signal from the sample to an optimal value. Furthermore, a varying magnetic field may be used to induce the bias voltage, as discussed further below.

Induced voltage bias for eliminating DC contact probes

Systems and methods are described for characterizing SHG response of layered semiconductor materials subjected to a discrete electric field across their interface without the use of contact bias probes in a system that synchronizes the gating of a detection laser's pulse and/or a detector with a predetermined amplitude of voltage applied to the sample to produce an AC, variable or pulsed bias voltage corresponding to or coordinated with the induced voltage field at the surface to be interrogated.

The target hardware includes a SHG device (e.g., further described in section II of U.S. provisional application No. 61/980,860 entitled "CHARGE DECAY MEASUREMENT SYSTEMS AND METHODS," filed on 4 months 17, 2014) along with means (e.g., configured as an inductive component) for inducing a voltage at or along the "device" surface of a sample without contact. Such members or components may be contacted by a back side contact with the probe or a conductive chuck, a capacitively coupled probe involving connection to a power source also being contacted by the back side contact probe or such a chuck, or by applying a varying magnetic field to the sample for the purpose of inducing an external voltage field across its multi-layer interface.

An instantaneous electric field generated by a variable waveform (optionally AC) power supply (via any of the above methods) induces an electric field across the interfaces of the multi-layer semiconductor material. The relationship between voltage and material interface electric field may be modeled by a transfer function or otherwise, including by taking into account various (capacitive or other) external influences. Given a particular amplitude and frequency of the AC (or other) current, the output of this function may be employed as a timing cue to trigger the laser shutter and/or photon counter simultaneously for SHG characterization of the test point for a constant near instantaneous value of the electric field amplitude at the interface. Thus, the system is also able to simulate a constant (DC) voltage applied to the topside (i.e., at the device layer of the substrate) via the contact electrical probes.

By applying AC directly to the backside of the sample, the system begins with the chuck in a "neutral" or ground state, and the bulk and device layers at an equilibrium potential. An alternating bias voltage is then applied to the chuck in electrical contact with the bulk or substrate layer of semiconductor material. Since the device layer is separated from the bulk by the buried oxide layer and is not in direct contact with a conductor, a potential field or voltage will be created (i.e., induced) between the device and bulk layers.

Alternatively, a capacitively coupled probe that resides nearby (within about 1mm to about 2 mm) but does not contact the top side of the sample may be employed. In this regard, a preferred method may be a plate sized to cover (but not contact) the entire wafer, hovering with an aperture for the incident laser to pass through on its way to the sample and for the SHG beam to pass through on its way out of the sample.

In some implementations, a non-contact electrode may be implemented using MEMS technology. For example, in one implementation, a Si wafer may be oxidized on both sides. A spiral or grid electrode may then be placed on one or more locations on the wafer by deposition. Oxide material may be removed from the backside of the wafer at those locations. In such embodiments, the electromagnetic field applied to the electrode may be inductively biased to the wafer through near field inductive coupling. The magnetic field generated by an external current may be used to generate current across the wafer by inducing current in the deposited electrode. Other methods of implementing a non-contact probe may also be used.

In any event, the SHG methodology is used to interrogate a sample, for example, as further described in section I, entitled "PUMP AND PROBE TYPE SHG METROLOGY", and/or section III, entitled "TEMPERRATURE-CONTROLLED METROLOGY", entitled "TEMPERATURE-CONTROLLED METROLOGY", filed on even date 17 at 2014, U.S. provisional application Ser. No. 61/980,860, entitled "WAFER METROLOGY TECHNOLOGIES", the entire contents of which are incorporated herein by reference. The same applies with respect to other embodiments discussed below.

Regardless, in the target embodiment, the SHG signal will be synchronized with the power supply because of the need to monitor the SHG, which varies as a function of the voltage across the interface. This synchronization may be accomplished by controlling the laser and SHG signal processing software for SHG generation, separate lasers, or SHG signal processing software alone in real time as the voltage changes. The voltage of the chuck may also be controlled.

The advantage of this synchronization is that SHG measurements that bias voltages similar to those of DC bias voltages can be obtained without the use of contact voltage bias probes on the front surface of the wafer. Instead of applying a DC bias, the system will collect SHG data at discrete points over the voltage period using an AC bias that is synchronized with the SHG measurement and/or generation. The AC bias is applied using near field inductive coupling or capacitive coupling via the sample. SHG data collected using these bias techniques will yield the same material property information as the DC biased SHG.

To reduce or minimize noise and obtain a statistically relevant indicator of SHG intensity that varies as a function of voltage across the interface, multiple photon counting windows may be required, as described further below.

Induced voltage bias for characterizing interface leakage

Systems and methods are described that characterize interface leakage currents and/or carrier injection energies between layers of layered (e.g., semiconductor) material using SHG applied to the layered semiconductor material according to the above and a voltage change, such as alternating, variable, and/or pulsed voltage or current signals or a device that alters the magnetic field in a manner that induces a voltage change in the device layers of a sample.

Interface leakage current and/or carrier injection energy between layers can be characterized by measuring SHG response from optical pulses generated by pulsed lasers directed at a layered semiconductor/dielectric structure at or shortly after application of an alternating, variable or pulsed voltage to the layered semiconductor material. In some embodiments, the time evolution of the SHG signal from the interface, which varies as a function of the time constant of decay of the induced voltage, may be measured. This yields information about the charge carrier mobility across the interface.

An induced voltage bias for characterizing the threshold carrier injection energy.

Systems and methods for SHG measurement in conjunction with a varying electric field application at a sample device layer are described in lieu of using tunable wavelength laser excitation to determine an energy threshold for photo-induced charge carrier injection into dielectrics in a layered semiconductor material. More specifically, to measure the threshold energy required for photo-induced charge carrier injection into the dielectric, the material may be exposed to a substantially monochromatic incident photon beam for SHG generation and then the voltage across the interface of the exposed layered semiconductor material is progressively changed, thereby measuring the SHG signal count at each incremental voltage change, until the SHG response has a significant inflection or discontinuity or abrupt change in slope compared to the previous measurement. Such slope change may be a maximum or minimum (e.g., local maximum or minimum) or a spike or step function, etc. The net charge change transfer due to all such procedures can be described as the integration of the specific gravity of the third harmonic injection current, the "forward" leakage current to the dielectric due to the strong electric field, and the "reverse" discharge leakage current. Substitution into equation form: q (t) = ≡ (I _χ +I _E -I _L ) dt the dynamics of this curve shape (bending moment and time saturation moment) will then provide information for determining the threshold carrier injection energy.

Drawings

Various aspects of various embodiments of different inventive variants are schematically illustrated in the figures.

FIG. 1A is a diagram of an embodiment of an SHG metering system herein; fig. 1B is a perspective view of a chuck for use in such an SHG system. Fig. 1C is a diagram of another SHG metering system embodiment herein.

Fig. 2A/2B and fig. 3A/3B show diagrams of exemplary pump/probe system usage for generating characteristic SHG signals.

Fig. 4 is a diagram showing the use of a probe/pump system to determine the threshold injection carrier energy.

Fig. 5 is a flow chart detailing a method for generating a signal as presented in the figure.

Fig. 6A-6C are diagrams of embodiments of the system.

FIG. 7 is a diagram of system functions; FIGS. 8A and 8B are diagrams showing the manner in which this function is performed; fig. 9 shows the system functions in a graphical output.

FIG. 10 and FIG. 11 depict an embodiment of a SHG interrogation related method; fig. 12A-12E depict temporal dynamics associated with the system of fig. 6C that may be employed in the methods of fig. 10 and 11.

FIG. 13 depicts a current-based interrogation method for observing transient electric field decay; fig. 14A and 14B illustrate hardware configurations that may be employed in the method of fig. 13.

Fig. 15A and 15B are schematic diagrams of SHG system components as may be used herein.

FIG. 16A is a perspective view of a first chuck arrangement herein; fig. 16B is a side cross-sectional view of the chuck arrangement of fig. 16A.

FIGS. 17A and 17B are perspective, partially cut-away views of a second chuck arrangement herein; fig. 17C is a cross-sectional top view of the chuck of fig. 17A/17B.

Fig. 18A and 18B relate to AC voltages applied to and present in a sample for DC bias probe cancellation.

Fig. 19A and 19B relate to AC voltages applied to and exhibited in a sample for testing leakage current.

Fig. 20 shows an aspect of an exemplary sample detection system 4000 that characterizes a sample using a Second Harmonic Generation (SHG) signal. In the example shown, a pulsed laser source 4100 is directed at the sample 4302 to be detected. One or more detectors 4201, 4210 are positioned to collect light 4400 of the second harmonic wavelength emitted by the sample 4302. In some cases, detector 4201 may be a detector module including detector 4210 and one or more optical components. In some cases, detector 4201 or detector 4210 may constitute a detector array (e.g., a one-dimensional or two-dimensional detector array) comprising a number of pixels. The detectors 4201, 4210 may be positioned at different locations (e.g., metrology locations) or moved to different locations to sample light at different angles (e.g., different tilt angles and/or different azimuth angles). Detectors 4201, 4210 may also contain filters 4230 to eliminate light of wavelengths other than the second harmonic, and may have polarization filters 4220 to select different light polarizations. Additional detectors may be used to detect light of the dominant wavelength. The sample 4302 may be mounted on an object table 4301 that is movable (such as laterally) to position a portion of the sample below the incident light 4110. Additionally or alternatively, the object table 4301 can include height adjustment and rotation (e.g., to provide different azimuth angles relative to an axis of rotation (e.g., the z-axis in fig. 20) perpendicular to the sample surface).

Fig. 21 shows an exemplary cross section of a semiconductor device/part of a feature of a semiconductor device (a FinFET transistor geometry 4500). The exemplary FinFET structure may include some combination of a silicon substrate 4540, a vertical silicon "fin" 4510, an oxide layer 4520 covering the fin, and a conductive gate contact 4530.

Fig. 22 shows an example FinFET array structure that includes several FinFET transistors. FinFET geometry 4500 repeats along one-dimensional array 4560. In some cases, the SHG signals generated by such a FinFET array (e.g., when illuminated by an incident laser beam) may be simulated using computer modeling and the effects of different parameters (e.g., height, width, pitch, periodicity, shape, etc.) on the resulting SHG signals (e.g., on the intensity of the SHG signals) may be simulated using computer modeling. For example, fig. 24 shows the results of simulating SHG signal strength for an identical FinFET transistor array when the width of the fin is changed from 1nm to 10 nm.

Fig. 23 shows an exemplary procedure for predicting SHG signals generated by a sample (e.g., structure in a sample). In various implementations, sample geometry and material properties 4610 and incident beam parameters 4620 may be used as inputs into an SHG modeling software 4630, e.g., SHG modeling software 4630 may be used to model SHG signals generated by structures on the sample having a particular geometry and output results regarding the SHG signals. In various embodiments, the output of the SHG modeling software may be a pattern of emissions of the SHG signal generated by the structure. In some cases, the emission pattern may be further processed using a computer model of a detector 4640 (e.g., a detector for generating SHG signals) that provides predictions of signals 4650 that may be output by a detector included in an SHG system (e.g., the SHG sample detection system shown in fig. 20) for characterizing samples.

Fig. 24 shows example simulated intensities of SHG signals (filled circles) for the structure shown in fig. 22 for several fin width values from 1nm to 10 nm. The figure also shows how an SHG signal measurement can be used in conjunction with the simulation results to determine parameters of the device under test. The computer modeling of fig. 24 may be repeated for variations in a device geometry parameter (e.g., fin width, fin height, etc.). In the example shown, the fin width is changed from one nanometer to ten nanometers in the simulation, and the results are stored in, for example, computer memory. The results are shown as a graph 4670. An experimental data point 4680 is also plotted on the chart. In various implementations, an SHG signal may be measured using an SHG system (such as shown, for example, in fig. 20, 25, or 26) or using another configuration and the modeled results of the measured SHG signal and SHG signals for different device parameters (e.g., fin widths) may be compared to determine possible parameter values (e.g., fin widths) associated with the measured SHG signal. For example, the measured SHG signal strength value 4680 shown in fig. 24 may be compared to signal strength values determined for different parameter values (e.g., fin width) using modeling to estimate a parameter value (e.g., fin width) associated with the measured SHG signal strength. In fig. 24, for example, the fin width is determined to be 5.5 nanometers by interpolating between calculated SHG intensity values, such as for five and six nanometer fin widths.

Fig. 25 shows an exemplary SHG system including detectors for measuring SHG signals generated by an illuminated area 4300 and a number of (tilt) angles on a sample. Additional SHG information collected via different angles may be used to determine a particular critical dimension (e.g., width or height or pitch, etc.). In some cases, additional SHG intensities collected along different angles may be used to improve the accuracy of the estimated value of the geometric parameter of the device.

Fig. 26 illustrates an exemplary SHG-based sample characterization configuration system 8000 for determining critical dimensions (SHG-CD) that uses a lens 4720 to perform angular resolved measurement of SHG signals generated by a sample under test. Different tilt angles are mapped to different positions on a linear (1D) or area (2D) detector array. Thus, different SHG signal intensities measured at different pixels of the detector array may correspond to different tilt angles of the measured SHG signal.

FIG. 27 illustrates an exemplary model-based metrology program. Data collected from SHG measurements is compared to estimated results from a previously generated model to calculate a structure of a device or a structural change of a device. In some cases, the model may be generated from data of samples having known values of corresponding parameters, a computer model of SHG signals generated by structures having known designs (e.g., geometric parameters), or a model derived from a machine learning method. Metrology procedures can be used to mark issues with semiconductor device or chip fabrication processes that result in deviations of device parameters such as physical parameters (e.g., width, height, pitch, shape, etc.) that are outside of certain tolerances.

Fig. 28 illustrates an exemplary feedback process for adjusting at least a portion of a semiconductor device or chip fabrication process. In this example, the SHG signal may be used to provide feedback signals to previous processing tools upstream of the manufacturing line to correct for observed or detected device measurement variations (e.g., measurements associated with a geometric device parameter).

FIG. 29 shows an exemplary feed-forward procedure for adjusting at least a portion of a semiconductor device or chip fabrication process. In this example, the SHG signal may be used to provide a feed forward signal to a downstream or subsequent processing tool to correct for observed or detected device measurement variations (e.g., measurements associated with a geometric device parameter).

Fig. 30A is a block diagram of an example SHG-CD system 4950, which includes an optical system 4952, a control system 4954, and a computing system 4956.

Fig. 30B is a block diagram of another example SHG-CD system 4960, which includes an optical system 4952 and an interface 4952 in communication with the optical system 4952.

Detailed Description

Monitoring the "critical dimension" (CD) of semiconductor devices produced by a manufacturing line is an important aspect of semiconductor manufacturing. Given even small variations in a critical dimension (e.g., due to a process variation) can affect the performance of semiconductor devices, capturing the variations at an early stage of the fabrication process can be advantageous in avoiding the production of large numbers of defective devices.

Conventional metrology tools for semiconductor device monitoring may not be able to meet many of the desired attributes of a metrology tool, including sensitivity, accuracy, repeatability, reliability, and cost of monitoring, simultaneously. The optical metrology tools, techniques, and systems described below can overcome some challenges associated with semiconductor device monitoring (e.g., online monitoring) using second harmonic light (also referred to as second harmonic generated light) as a nondestructive probe for sample monitoring and evaluation. More specifically, a Second Harmonic Generation (SHG) system (referred to herein as SHG-CD) for determining the Critical Dimension (CD) of a sample is described. The SHG-CD may illuminate a sample with one or more light beams and use light generated by the resulting second harmonic emitted by one or more devices on a sample to determine the physical structure (e.g., shape and/or size) of the devices and/or to monitor changes in such features. The sample may include devices and structures (e.g., complete and/or incomplete devices and structures fabricated on a wafer). In some cases, SHG-CD may also use second harmonic light to determine the material properties (or changes in material properties) of a sample or of a device or structure included in the sample.

SHG-based optical wafer metering technology

Part I

FIG. 1 is a diagram of a system 100 as may be employed in connection with a method for interrogating a sample to potentially provide information about a material property (e.g., a property of an electronic structure) of the sample. Other suitable system variations are presented in section II of U.S. provisional application No. 61/980,860 entitled "CHARGE DECAY measure SYSTEMS AND METHODS," entitled "WAFER METROLOGY TECHNOLOGIES," filed on 4 months 17, 2014, for example, with respect to intermediate optics, including optical delay lines, and optional electrode features.

As shown, the system 100 includes a main or detection laser 10 for directing an interrogation beam 12 of electromagnetic radiation toward a sample wafer 20 held by a vacuum chuck 30. As shown in fig. 1B, chuck 30 includes or is set on an x-stage and a y-stage, as well as a rotational stage for positioning a sample site 22 across the wafer relative to where the laser is aimed. The x-y stage enables scanning of multiple wafer surface sites or locations 22 without moving other hardware. A rotary stage optionally enables evaluation of crystal structure effects (such as strain) on the SHG, and associated defects or regions of interest on the characterized material. Further optional features, aspects and/or uses of the cartridge 30 are presented in section IV entitled "FIELD-BIASED SHG METROLOGY" and section III entitled "TEMPERATURE-CONTROLLED METROLOGY" of U.S. provisional application Ser. No. 61/980,860 entitled "WAFER METROLOGY TECHNOLOGIES" filed on month 4, 17, which are both incorporated herein by reference in their entirety. Sample site 22 may comprise one or more layers. Sample site 22 may comprise a composite substrate comprising at least two layers. Sample site 22 may comprise an interface between two different materials (e.g., between two different semiconductor materials, between two differently doped semiconductor materials, between a semiconductor and oxide, between a semiconductor and dielectric material, between a semiconductor and a metal or oxide and a metal).

When the system 100 is in use, the beam 14 of reflected radiation directed at a detector 40 will contain an SHG signal. The detector may be any of a photomultiplier tube, a CCD camera, a burst detector, a photodiode detector, a high-speed scanning (streak) camera, and a silicon detector. The system 100 may also include one or more shutter-type devices 50. The type of shutter hardware used will depend on the time frame in which the laser radiation will be blocked, dumped (dump) or otherwise directed away from the sample site. An electro-optical blocking device, such as a pockels cell or kerr cell, may be used to obtain a very short blocking period (i.e. having a blocking period of about 10 ^-9 Second to 10 ^-12 Actuation time in seconds).

For longer blocking time intervals (e.g., from about 10 ^-5 Seconds and above), a mechanical shutter or flywheel chopper type device may be employed. However, the electro-optic blocking device will allow a wider range of materials to be tested according to the following method. Photon counting system 44 capable of discretely gating very small time intervals (typically on the order of picoseconds to microseconds) may be employed to resolve time dependent signal counts. For faster time frames, an optical delay line may be incorporated as described above.

The system 100 may include an additional electromagnetic radiation source 60 (also referred to as a pump source). In various embodiments, the radiation source 60 may be a UV flash lamp shown emitting laser light of a directed beam 62 or emitting a divergent or optically collimated pulse 64. In the case of a laser source, its beam 62 may be collinear with beam 12 (e.g., as directed by an additional mirror or prism, etc.). The wavelength of light output by source 60 may be anywhere from between about 80nm and about 1000 nm. With shorter wavelengths in this range (e.g., less than about 450 nm), charge excitation may be driven with fewer photons and/or with lower peak intensities than longer wavelengths.

For a flash lamp, the energy of each flash or the power level during a flash may be substrate material dependent. A flash lamp that produces a total energy of 1J to 10kJ per flash would be suitable for fully depleted silicon on insulator (FD-SOI). However, a pulsed or constant UV source is also possible. An important factor in pump performance and use is the injection of charge carriers into the dielectric of the material to be interrogated. Manufacturers of suitable flashlights include Hellma USA, inc. and Hamamatsu Photonics K.K.

When a laser is employed as the source 60, it may be any of nanosecond, picosecond, or femtosecond or faster pulsed laser sources, which may even be a continuous solid state laser. In various embodiments, the pump source is tunable in wavelength. Commercial options for tunable lasers include the Velocity and Vortex tunable lasers of Spectra Physics. Additional tunable solid state solutions are available from solid state lasers of the LT-22xx series of LOTIS ltd.

Whether provided as a laser or a flash lamp, pump source 60 may be selected for relatively high average power. This may be from about 10mW to about 10W, but more typically from about 100mW to about 4W, depending on the material to be interrogated (again, this consideration ensures that the charge carrier mobility is induced in such a way that the charge carriers are injected into the interface of the material (e.g., dielectric interface), which may be material specific). The average power of pump source 60 is selected to be below the optical damage threshold of the material. For example, when the interrogation material comprises silicon, the pump source 60 may be selected to have an average optical power between 1W and 2W so as not to exceed the optical damage threshold of silicon.

The detection laser 10 may be any one of a nanosecond, picosecond, or femtosecond or faster pulsed laser source. Two options for current commercial lasers with the required peak power, wavelength and reliability are doped fiber and Ti: sapphire units. The Coherent's VITESSE and Spectra Physics MAI TAI laser is an example of a suitable Ti: sapphire device. Other related Ti: sapphire devices are also manufactured by femto assers Gmbh and other manufacturers. Suitable doped fiber lasers are produced by IMRA, onetelevision and Toptica Photonics. Picosecond and/or nanosecond lasers from many manufacturers (such as Hamamatsu) may also be an option depending on the substrate material and pump type. The laser 10 may operate in a wavelength range between about 100nm and about 2000nm with a peak power between about 10kW and 1GW, but deliver an average power of less than about 150 mW.

Various other optional so-called "intermediate" optical components may be employed in the system 100. For example, the system may include a dichroic reflective or refractive filter 70 for selectively transmitting the SHG signal coaxially with reflected radiation directly from the laser 10 and/or source 60. Alternatively, a prism may be employed to distinguish weaker SHG signals from the most strongly reflected main beam. However, a dichroic system as mentioned above may be preferred, as the prismatic approach has proven to be very sensitive to misalignment. Other options include the use of diffraction gratings or thin film (Pellicle) beam splitters. A beam 80 for focusing and collimating/column optics may be provided. Alternatively, filter wheel 90, polarizer 92, and/or zoom lens 94 units or assemblies may be employed in the system. Furthermore, angular (or arc) rotation adjustment (with corresponding adjustment for the detector) and on-line optics may be required.

In the implementation shown in fig. 1C, the beam 12 from the laser 10 may be split between two optical paths by a beam splitter 74. Beam splitter 74 may split beam 12 unevenly between the two optical paths. For example, 70% of the energy of beam 12 may be directed along a first optical path (e.g., as beam 16) and 30% of the energy of beam 12 may be directed along a second optical path (e.g., as beam 18). For another example, 60% of the energy of beam 12 may be directed along a first optical path and 40% of the energy of beam 12 may be directed along a second optical path. As yet another example, 80% of the energy of beam 12 may be directed along a first optical path and 20% of the energy of beam 12 may be directed along a second optical path. Thus, the splitting may be non-uniform (e.g., anywhere between 70% -30%, 80% -20%, 60% -40%, or the like, such as between 60% and 90% in one path and 40% to 10% in another path, and outside of such ranges), transmitting most of the power in the pump beam and a small amount of power in the probe beam. For example, the split may be 60% to 70% and 40% to 30% for the pump and probe, 70% to 80% and 30% to 20% for the pump and probe, 80% to 90% and 20% to 10% for the pump and probe, or 90% to 99.999% and 10% to 0.001% for the pump and probe, respectively. In different embodiments, for example, the probe beam may be between 0.001% and 49.99%, while the pump beam may be between 50.001% and 99.999%. The sum of the two beams may be 100% or close to 100%. In some cases, the segmentation may be determined by the particular material system being characterized. In the example shown in fig. 1C, 5% of the beam energy of beam 12 is directed along a first optical path and 95% of the energy of beam 12 is directed along a second optical path.

The beam splitter 74 may include a dielectric mirror, a beam splitter cube, a metal coated mirror, a thin film mirror, or a waveguide beam splitter. In embodiments, where beam 12 comprises an optical pulse, beam splitter 74 may comprise an optical component with negligible dispersion that splits beam 12 between two optical paths such that the optical pulse is not spread. As shown in fig. 1C, various mirror assemblies 2072 may be used to redirect or aim each of the beams.

Outputs from the detector 40 and/or photon counting system 44 may be input to the electronics 48. The electronic device 48 may be a computing device, a computer, a tablet computer, a microcontroller, or an FPGA. The electronic device 48 includes a processor that may be configured to execute one or more software modules. In addition to executing an operating system, the processor may be configured to execute one or more software applications (including a web browser, a telephone application, an email program, or any other software application). The electronic device 48 may implement the methods discussed herein by executing instructions contained in a machine-readable non-transitory storage medium, such as a RAM, ROM, EEPROM or the like. The electronic device 48 may include a display apparatus and/or a graphical user interface to interact with a user. Electronic device 48 may communicate with one or more devices via a network interface. The network interface may include a communicable transmitter, receiver, and/or transceiver, for example Such as a wired ethernet network,Or a wireless connection.

With respect to other options, it is desirable to improve the signal-to-noise ratio of the SHG count because a SHG signal is weaker than the reflected beam from which it is generated. As the photon count gating time for photon counting system 44 is reduced for the blocking and/or delaying processes described herein, improvements become more important. The noise reduction method that can be used is to actively cool the photon counter. This can be accomplished using cryogenic fluids such as liquid nitrogen or helium or through solid state cooling using a Peltier device. Other areas of improvement may include the use of Marx Bank Circuits (MBCs) as related to shutter speed. In addition, the system 100 may be incorporated online within a production environment. The front or back line components of the system 100 may include any of an epitaxial growth system, a lithography and/or deposition (CVD, PVD, sputtering, etc.) system.

Referring now to fig. 2A/2B and 3A/3B, these are schematic diagrams illustrating exemplary types of SHG curves that may be generated by the target pump/probe system in its method of use. In fig. 2A and 2B, the time scale for obtaining such signals is on the order of milliseconds (10 ^-3 s). Thus, these are "fast" procedures. As discussed further below, they may provide several orders of magnitude of temporal improvement over existing methods. For example, a flash lamp capable of exposing the entire surface of a test material to UV radiation prior to SHG detection significantly reduces the overall scan time, as continuous metrology at various points may not be required.

Specifically, in fig. 2A, an SHG signal 200 having an initial intensity 202 is measured. The signal is generated by source radiation applied at a surface location. At a given time offset (O ₁ ) After increasing the pump radiation (to the probe that remains on), the signal strength drops to a lower level 206 along a time-dependent curve 204. Conversely, in FIG. 2B, the time offset (O ₂ ) Is applied after pump radiation, the SHG signal 2 of lower level 212 is generated solely from the detected radiation00' increases along a time dependent curve 214 to a higher plateau 216. Signals 200 and 200' also include a time-independent component or portion at the beginning and end of the curve.

Depending on the substrate material and the different laser powers (e.g., the laser power of the pump in this case), both observations in fig. 2A and 2B may be made with the target system. In various embodiments, charge separation includes electrons and holes that separate from each other after excitation from a photon. Implantation of photons from laser light from the valance band of silicon into SiO ₂ Electrons in the conductive strip are mainly trapped on the top surface of the oxide. The holes are mainly concentrated near Si/SiO ₂ In the silicon valence band of the interface. This charge carrier separation due to excitation from incident radiation or from internal photoemission contributes to the electric field present inside the target system, which in turn alters the measured SHG. Various factors such as the presence of gaseous oxygen at the test site, and the composition and structure of the sample in question will determine whether or not to observe as in fig. 2A or fig. 2B.

In fact, a combination of signals 200 and 200' has been observed in some instances. In those cases, the signal strength first drops from a peak to bottom and then rises again to an asymptote. Generally, the SHG intensity curve is determined by a nonlinear polarizability tensor, which in turn is affected by molecular orientation, atomic organization, electronic structure, and external fields. Charge carriers moving across the interface will change the charge state in the structure and the electric field in the sub-interfacial layer where SHG signal generation occurs. Depending on the type of charge carrier (positive or negative) across the interface, and the initial state of the field across the interface, different time dependent curves will be observed. The intensity of the detected SHG signal may depend on various factors including spot size, average laser power, and peak laser power. In various embodiments, the system 100 may be configured to detect SHG signals having an intensity in a range between about 400 counts/sec and about 7 million counts/sec. The pump/probe system described herein can reduce the time required for charge carriers to move across the interface to reach a saturation level. In various embodiments, in the pump/probe system described herein, the time required for charge carriers to move across the interface to reach a saturation level may be between 1 millisecond and 1000 seconds. Since it may be advantageous to obtain a temporal evolution of the SHG signal when the charge carrier density in the region containing the interface is below saturation and when the charge carrier density in the region containing the interface reaches a saturation level, the system may be configured to obtain SHG signal measurements within about 1 microsecond after switching on/off pump radiation. For example, the system may be configured to obtain SHG signal measurements within 10 seconds after turning on/off pump radiation (or detection radiation), within about 6 seconds after turning on/off pump radiation (or detection radiation), within about 1 second after turning on/off pump radiation (or detection radiation), within about 100 milliseconds after turning on/off pump radiation (or detection radiation), or within about 1 millisecond after turning on/off pump radiation (or detection radiation), within 1 nanosecond after turning on/off pump radiation (or detection radiation), or within any range formed by any of these values (e.g., within a period of time greater than one, greater than one microsecond, greater than one millisecond, etc.), and outside any of those ranges. This equivalence and range is applicable to data obtained from a single point, but can be increased to a substantial area of the wafer, up to and including the entire wafer at a time, using appropriate imaging optics. As indicated by brackets above, this equivalence and range also apply to detecting radiation. Reducing the charging time and the time required to obtain the SHG signal may allow for faster test interfaces and thus increase throughput of the test and/or manufacturing line.

By way of comparison, fig. 3A and 3B schematically show SHG signal curves 300 and 300' for corresponding materials, where only one radiation source (in this case, a high average power and high peak power laser) is used to interrogate the substrate as in the prior art SHG. The time scale for generating the signals 300 and 300' in fig. 3A and 3B is about several tens to several hundreds (10 ² s) seconds.

During this time, such signals (as in fig. 2A and 2B) include lower and upper plateau regions 306, 316 that may be characterized after the initial signal 302 and/or the time dependent signal. Thus, while similar (or identical) analysis can be performed on signals 200/200 'and 300/300', the main difference is that the use of the target system (i.e., using a lower peak power femtosecond probe laser in combination with a higher average power pump for material pre-excitation) allows for greatly improved temporal efficiency in obtaining the necessary signal information. In addition, the target method provides a way to more easily determine time-independent SHG measurements without the use of a filter wheel or some other method.

In any event, fig. 4 illustrates a method for determining the threshold injection carrier energy. In this case, the pump comprises a tunable wavelength laser. This allows the output frequency (and thus the energy e=hν) of photons incident on the sample from the pump to ramp up over time. The observed SHG activity is shown as signal 400. With the pump laser so applied or engaged, the initial SHG signal level 402 generated by the application of a probe laser is observed to be the point at which the signal suddenly changes (i.e., inflection, discontinuity, maximum, minimum, step function, spike, or sudden change of some slope occurs at 404). Taking the frequency at this point corresponds to a threshold energy. In various embodiments, the threshold energy is such that electrons cross two materials (such as two semiconductor materials or a semiconductor material and a dielectric material (e.g., si and SiO ₂ Si and Si ₃ N ₄ Si and Ta ₂ O ₅ Si and BaTiO ₃ Si and BaZrO ₃ Si and ZrO ₂ Si and HfO ₂ Si and La ₂ O ₃ Si and Al ₂ O ₃ Si and Y ₂ O ₃ Si and ZrSiO ₄ ) An interface between the semiconductor material and the conductive strip of another semiconductor material). The system 100 may be configured to measure a threshold energy in a range between about 1.0eV and about 6.0 eV. The systems and methods described herein may be configured to determine threshold energy for various interfaces (e.g., such as between two different semiconductors, between a semiconductor and a metal, between a semiconductor and a dielectric, etc.).

Fig. 5 is a flow chart 500 illustrating an embodiment of a method for characterizing a semiconductor device with SHG. Indicating various program flow paths. Any such methods may begin 502 where a sample is positioned at a desired location (e.g., typically by positioning chuck 30 after a wafer 20 has been secured to chuck 30). Progressive positioning (i.e., repositioning) may occur after any given SHG detection event 520 as further described for scanning multiple surface locations or even each surface location of a sample in an area of the sample. Alternatively, this action may occur after a given determination (or "return" option indicated by the dashed line) is made at 540 regarding a detected SHG signal. Further details regarding substitution decisions may be found with reference to the other portions of the application referenced above. In any case, a given flow path is selected after the sample is positioned or repositioned (or another flow path may be run at the same surface location after different data are sequentially generated).

After one program flow path (partially solid line), the source radiation is applied to the sample surface at a given location at 504. Next, at 506, pump source radiation is applied. In this example, pump radiation is applied in a different manner that increases photon energy linearly by decreasing the radiation wavelength (as needed). The resulting SHG is detected at 520. At 542, signal analysis (according to the example in fig. 4) allows for determining the carrier injection threshold energy. In various embodiments, the energy radiated by the pump may correspond to a threshold energy of the semiconductor interface. Thus, the energy of the pump radiation may be between about 1.0eV and about 6.0 eV. For example, to determine a Si and SiO crossing ₂ The threshold energy of the interface, the threshold energy of the pump radiation may vary between about 4.1eV and about 5.7 eV. The energy variation of the pump radiation can be accomplished by changing the frequency (or wavelength) of the radiation. For example, to interrogate a sample having an expected value of threshold energy of about 3.2eV, the wavelength of pump radiation may be varied between about 443nm and about 365 nm. In various implementations, the energy of the pump radiation may be below the threshold energy of the semiconductor interface, as photons from the pump radiation may produce electrons having twice the energy (e.g., when a single electron absorbs two photons). In such embodiments, the charge time is increased, which may provide for an increase in the charge time And (5) observing the added resolution and intensity. Increasing the charging time also increases the time required to test a sample site, which can reduce throughput.

After another flow path (partially dashed line), pump radiation is applied to the substrate at 508. This application may be directed only to the surface to be interrogated immediately (e.g., by a laser) or the entire surface of the wafer (e.g., using a flash lamp). Next, at 510, a selection of samples to be interrogated is exposed to the detection source radiation. The resulting SHG is detected at 520. The pump-probe-detection aspect of the method may then potentially repeat after sample repositioning at 502. However, as indicated, action block 508 may be skipped and re-pumping may be avoided or omitted from a sequential scanning procedure, as in the above example where the entire substrate is initially exposed to pump radiation. In any case, at 544, any of a variety of SHG-based signal analyses may be performed to make a determination other than for the threshold energy as in block 542, as discussed elsewhere in this patent application.

After another program flow path (partial dot-dashed line/centerline), before and after applying pump radiation at 508, probe interrogation is performed at 504 and 510, with SHG signal data collection at 520 immediately after probe radiation application at 504 and 510. Again, this method may be performed recursively to sample several sites (such as a substrate or each section of a region thereof) to return to the flowchart element 502 to reposition and repeat the probe-detection-pump-probe-detection method or sub-method.

Notably, any of the SHG signal analysis methods or sub-methods (generally included in blocks 540 and 542) may be performed in real-time, such as in a transient or near-transient output. In so doing, any of the spectral properties determined from the collected data may be calculated by a software package, either by integrated software on the machine or remotely. Alternatively, SHG signal analysis may be handled in post-processing after some or all of the SHG data has been detected or collected.

The systems and methods described herein may be used to characterize a sample (e.g., a semiconductor wafer or a portion thereof). For example, the systems and methods described herein may be used to detect defects or contaminants in a sample as discussed above. The systems and methods described herein may be configured to characterize a sample during the manufacture or production of a semiconductor wafer. Thus, the system and method may be used along a semiconductor manufacturing line in a semiconductor manufacturing facility. The systems and methods described herein may be integrated with a semiconductor manufacturing/production line. The systems and methods described herein may be integrated into a semiconductor wafer fab line (fab line) with automated wafer handling capabilities. For example, the system may be equipped with an Equipment Front End Module (EFEM) that accepts the attachment of a wafer cassette, such as a Front Opening Unified Pod (FOUP). Each of these cassettes may be delivered to the machine by a human operator or by an automated cassette handling robot that moves the cassette along the manufacturing/production line between processes.

In various embodiments, the system may be configured such that once the cassette is mounted on the EFEM, the FOUP is opened and a robotic arm selects individual wafers from the FOUP and moves them through automatically actuated doors included in the system, into an opaque cassette, and onto vacuum chucks with bias capability. The chuck may be designed to fit complementarily with the robotic arm so that it can place the sample on top. At some point in the process, the wafer may be held over a scanner to identify its unique laser mark.

Thus, a system configured to be integrated in a semiconductor manufacturing/assembly line may have automated wafer handling capabilities from a FOUP or other type of cassette; with the EFEM as discussed above, chucks designed in a manner compatible with robotic handling, automated light-tight doors that open and close to allow movement of robotic bars/arms, and software signaling integration of the EFEM for wafer loading/unloading and wafer identification.

Part II

FIG. 6A is a diagram of a first system 2100 as may be employed in connection with interrogating a sample using second harmonic generation. Alternative systems 2100' and 2100 "are shown in fig. 6B and 6C. Each system includes a main laser 2010 for directing a main beam 2012 of electromagnetic radiation at a sample wafer 2020, the sample being held by a vacuum chuck 2030. Chuck 2030 includes or is set on an x-stage and a y-stage, as needed, for positioning a sample location 2022 across the wafer relative to where the laser is aimed. The beam 2014 of reflected radiation directed to a detector 2040 will contain an SHG signal. The detector may be any one of a photomultiplier tube, a CCD camera, a burst detector, a photodiode detector, a high-speed scanning camera, and a silicon detector. The sample site 2022 may contain one or more layers. The sample site 2022 may comprise a composite substrate comprising at least two layers. The sample site 2022 may comprise an interface between two different materials (e.g., between two different semiconductor materials, between two differently doped semiconductor materials, between a semiconductor and an oxide, between a semiconductor and a dielectric material, between a semiconductor and a metal, between an oxide and a metal, between a metal and a metal, or between a metal and a dielectric).

Again, common to the various embodiments is the inclusion of one or more shutter devices 2050. Such shutter devices 2050 are employed as described in connection with the methodologies below. The type of shutter hardware used will depend on the time frame in which the laser radiation will be blocked, dumped or otherwise directed away from the sample site.

An electro-optical blocking device, such as a pockels cell or kerr cell, is used to obtain very short blocking periods (i.e. having a blocking period of about 10 ^-9 Second to 10 ^-12 Second switching time). For longer blocking time intervals (e.g., from about 10 ^-5 Seconds and above), a mechanical shutter or flywheel chopper type device may be employed.

However, the electro-optic blocking device will allow a wider range of materials to be tested according to the following method. Photon counting system 2044, which is capable of discretely gating very small time intervals (typically on the order of picoseconds to microseconds), may be included to resolve time dependent signal counts.

Hardware is considered to push the method into a faster time frame. That is, as shown in fig. 6C, the system may include delay line hardware 2060. For the correspondingA number of delayed interrogation events, beam splitting and switching (or shutter on/off) between set time delay lines is possible. However, a variable delay line may be preferred because the delay line is self-supporting (although many methodologies may require only 10 ^-12 Second delay) to multiple transient charge decay interrogation events on the timeframe in the range of the last tens of nanoseconds of the pump pulse. If a slower, khz repetition laser is used, the desired delay time may even fall into the microsecond range. And while this hardware is particularly suited to performing the target methodology (where the method is considered to be heretofore unknown, this hardware) it may be used for other purposes as well.

In the embodiment shown in fig. 6C, beam 2012 from laser 2010 may be split between two optical paths by a beam splitter 2070. Beam splitter 2070 may split beam 2012 unevenly between the two optical paths. For example, 70% of the energy of beam 2012 can be directed along a first optical path (e.g., as beam 2016) and 30% of the energy of beam 2012 can be directed along a second optical path (e.g., as beam 2018). As another example, 60% of the energy of beam 2012 can be directed along a first optical path and 40% of the energy of beam 2012 can be directed along a second optical path. For yet another example, 80% of the energy of beam 2012 can be directed along a first optical path and 20% of the energy of beam 2012 can be directed along a second optical path. Beam splitter 2070 may comprise a dielectric mirror, a beam splitter cube, a metal coated mirror, a thin film mirror, or a waveguide beam splitter. In embodiments, where beam 2012 includes an optical pulse, beam splitter 2070 may include an optical component with negligible dispersion that splits beam 2012 between the two optical paths such that the optical pulse is not spread. As indicated by the double arrow in fig. 6C, the interrogation beam 2016 exiting a beamsplitter 2070 from the main beam 2012 can be lengthened or shortened to change its arrival time relative to a pump beam 2018, wherein each beam is shown as directed or aimed by various mirror assemblies 2072. Another approach (mentioned above) employs optical fibers in the optical delay component and/or other optical paths (e.g., as set forth in U.S. patent No. 6,819,844, which is incorporated by reference herein in its entirety for this description).

The output from the detector 2040 and/or photon counting system 2044 may be input to an electronic device 2048 (see, e.g., fig. 6A and 6B). The electronic device 2048 may be a computing device, a computer, a tablet computer, a microcontroller, or an FPGA. The electronic device 2048 includes a processor or processing electronics that may be configured to execute one or more software modules. In addition to executing an operating system, the processor may be configured to execute one or more software applications (including a web browser, a telephone application, an email program, or any other software application). The electronic device 2048 may implement the methods discussed herein by executing instructions contained in a machine-readable non-transitory storage medium, such as a RAM, ROM, EEPROM, etc. The electronic device 2048 may include a display apparatus and/or a graphical user interface to interact with a user. The electronic device 2048 may communicate with one or more devices via a network interface. The network interface may include a transmitter, receiver, and/or transceiver that may communicate via a wired or wireless connection.

Another potential aspect of the system 2100″ relates to the manner in which the initial beam splitter operates. That is, the splitting may be non-uniform (e.g., 70% -30%, 80% -20%, 60% -40%, or any range therebetween, such as between 60% and 90% in one path and 40% to 10% in another path, and outside of such ranges), transmitting a majority of the power in the pump beam and a minority of the power in the probe beam. For example, the split may be 60% to 70% and 40% to 30% for the pump and probe, 70% to 80% and 30% to 20% for the pump and probe, 80% to 90% and 20% to 10% for the pump and probe, or 90% to 99.999% and 10% to 0.001% for the pump and probe, respectively. In different embodiments, for example, the probe beam may be between 0.001% and 49.99%, while the pump beam may be between 50.001% and 99.999%. The sum of the two beams may be 100% or close to 100%. In some cases, the segmentation may be determined by the particular material system being characterized. The values to do so may help facilitate methods such as those shown in fig. 10 and 11, where the power involved in the SHG interrogation after material charging is desirably reduced or minimized as discussed below. Yet another aspect is that the pump beam and the probe beam are introduced at different angles. This method facilitates measuring pump and probe SHG responses separately. In such cases, two detectors, one for each reflected beam path, may be advantageously employed.

Various other optional optics distinguish the illustrated embodiments. For example, embodiments 2100 and 2100' are shown to include a dichroic reflective or refractive filter 2080 for selectively passing an SHG signal coaxial with reflected radiation directly from laser 2010. Alternatively, a prism may be employed to distinguish weaker SHG signals from the most strongly reflected main beam. However, a dichroic system as mentioned above may be preferred, as the prismatic approach has proven to be very sensitive to misalignment. Other options include the use of diffraction gratings or a thin film beam splitter. As shown in system 2100, a light beam 2082 for focusing and collimating/column optics may be provided. As shown in system 2100', a filter wheel 2084, a zoom lens 2086, and/or a polarizer 2088 may be employed in the system. Furthermore, angular (or arc) rotational adjustment (with corresponding adjustment for detector 2040 and on-line optical components) as shown in system 2100' may be required. An additional radiation source 2090, which is a laser emitting a directed beam 2092 or a UV flash emitting a divergent or optically collimated or focused pulse 2094, may also be incorporated into the system to provide such features as mentioned above in connection with section I of U.S. provisional application No. 61/980,860 entitled "PUMP AND PROBE TYPE SHG METROLOGY", filed on publication No. 61/980,860 of 2014, month 17, entitled "WAFER METROLOGY TECHNOLOGIES", and/or initial charging/saturation in the following methods.

In such systems, the laser 10 may operate in a wavelength range between about 700nm and about 2000nm, with a peak power between about 10kW and 1GW, but deliver an average power of less than about 100 mW. In various embodiments, an average power between 10mW and 10W should be sufficient. The additional light source 2090, which is another laser or a flash lamp, may operate in a wavelength range between about 80nm and about 800nm to deliver an average power between about 10mW and 10W. However, values outside of these ranges are possible.

With respect to other options, it is desirable to improve the signal-to-noise ratio of the SHG count because a SHG signal is weaker than the reflected beam from which it is generated. As photon count gating times are reduced for the blocking and/or delaying processes described herein, the improvements become more useful. The noise reduction method that can be used is to actively cool the detector. Cooling may reduce the number of false positive photon detections that are randomly generated due to thermal noise. This can be accomplished using cryogenic fluids such as liquid nitrogen or helium or through solid state cooling using a Peltier device. Other areas of improvement may include the use of Marx Bank Circuits (MBCs) as related to shutter speed.

These improvements may be applied to any of the systems of fig. 6A-6C. Likewise, any and all of the above features described above in connection with systems 2100 and 2100' may be incorporated into system 2100″. In fact, the mixing and matching of features or components is considered among all systems.

With such systems running the target methodology, various decisions heretofore not possible can be made using laser blocking and/or delay correlation techniques. Fig. 7 shows a program diagram or decision tree 2200 that represents such possibilities. That is, a detected so-called problem 2210 may be parsed between a defect 2220 (an extended defect such as a bond vacancy or dislocation, crystal Originated Particle (COP), or the like) and a contaminant 2230 such as copper inclusions or other metals in the form of point defects or clusters. For a defect, defect type 2222 and/or a defect quantification 2224 determination (e.g., in terms of density or extent) may also be made. For a contaminant, a contaminant type or class 2232 and/or a contaminant quantification 2234 determination may be made. This profiling and identification of species between defects and contaminants may be performed in conjunction with determining charge carrier lifetime, trap energy, trap capture cross-section, and/or trap density, followed by comparing these with values in a look-up table or database. Essentially, such tables or databases include a list of properties of materials as characterized by the target method, and then match the properties with entries in a table or database corresponding to particular defects or contaminants.

Trap capture cross-sections and trap densities can be observed in combination with the charge dynamics detected as needed. Regarding determining charge carrier lifetime and trap energy, the following equations based on the operation of i.lungstrom provide guidance:

tunneling time constant, phi of tunneling mechanism in which tau is trap discharge _r Representing trap energy, E _ox The strength of the electric field at the interface is represented and the remaining equation variables and context are described in I.Lundstrom, JAP, v.43, n.12, p.5045,1972 (the objects of which are incorporated by reference in their entirety). Further modeling and calculation options may be found in reference to section III of U.S. provisional application No. 61/980,860 entitled "temp tube-CONTROLLED METROLOGY," filed on 4 months 17 at 2014, which is incorporated herein by reference in its entirety.

In any event, decay curve data obtained by interrogation of a target sample may be used to determine parameters of trap energy and charge carrier lifetime by using solid models and related mathematics. A representative set of curves 2300, 2300' (such as those depicted in fig. 8A and 8B) may be calculated from the above equations (with fig. 8B highlighting the side or expanding the section of data from fig. 8A).

These curves demonstrate the relationship between time constant (vertical axis) and dielectric thickness (horizontal axis) for different trap or barrier energies. The vertical axis contains ultra-fast time scales as low as nanoseconds (1E-9 s). Horizontal axis tunneling distance (or dielectric thickness, in this example, the two terms are generally equivalent). The different curves are lines of constant barrier energy. For example, in FIG. 8B, if the dielectric thickness is 40 angstroms, electrons trapped in a trap having an energy depth of 0.7eV of the listed barrier energy will exhibit a release (detrapping) time constant of about 1E-5 seconds.

Further modeling using Poisson/Transport solvers can be used to determine trap density in MOS-like structures and more unique devices using charge carrier lifetime and known trap energies. Specifically, the light injection current due to the femtosecond optical pulse induces a burst of charge carriers reaching the dielectric conduction band. The average value of this current may be related to the concentration of carriers in the region and the lifetime of the carriers. The electric field across the interface is the proxy by which the SHG measures these phenomena.

In the plot of FIG. 8A, it can be observed (see dashed line) that for traps having an energy of about 3eV, 20 angstroms of oxide has a discharge time constant of 1 msec. To relate the plot to an example of use in a target system, assume a 20 angstrom oxide is interrogated after blocking laser excitation. As shown in fig. 8B (see highlighted box), the result will be an observable current from 1 musec to about 1msec and then all current is lost.

The decay curves discussed in this application may be the products from multiple procedures (e.g., charge relaxation, charge recombination, etc.) of traps with different energies and different relaxation/recombination time constants. However, in various embodiments, the decay curve may be generally represented by an exponential function f (t) =axp (- λt) +b, where a is the decay amplitude, B is the baseline shift constant and λ is a decay constant. This general exponential function can be used to approximate the characterization "degree of attenuation" from the experimentally obtained attenuation data curve. In various embodiments, half-life t may be used _1/2 The average lifetime τ and the decay constant λ to characterize the degree of decay of a decay curve (obtained experimentally or by simulation). For example, the parameters A, B and λ may be obtained from experimentally obtained decay data points, as discussed below. An average lifetime τ can then be calculated from the parameters A, B and λ using the theory of radioactive decay as a way of setting what is qualitatively referred to as a baseline of partial or complete decay. For example, in some embodiments, τ may be determined by the equation (t _1/2 ) /(ln (2)) is given.

In various embodiments, the state of charge may be considered to have decayed completely after the time span of three average use periods τ, which corresponds to a decay from full saturation to 95%. After a certain number of average use periods τ have elapsed, a partial decay may be signaled.

In operation, the system determines parameters (e.g., carrier lifetime, trap energy, capture cross-section, charge carrier density, trap charge density, carrier injection threshold energy, electron carrier lifetime, charge accumulation time, etc.) on a point-by-point basis over a portion of the wafer (e.g., die size portion) or the entire wafer based at least in part on the target methodology. The entire wafer (depending on the desired material, surface area, and scan density) may typically be scanned in less than about 10 minutes, with such parameters determined for each point scanned. In various embodiments, the position of the wafer may be scanned over a time interval between about 100 milliseconds and about 3 seconds. For example, the position of the wafer may be scanned in about 950 milliseconds.

The data matrix containing the spatial distribution of the determined parameters may be plotted as a heat map or contour map of the individual color codes of the respective parameters as a means for quantitative detection, feedback and presentation. Fig. 9 shows one such diagram 2400 depicting how a defect 2402 may be depicted. Any of the targets in fig. 7 may be shown in further detail. Once quantitative data is obtained, providing this output is merely a matter of changing the program code in the drawing program code/script file.

This information and/or other information processed hereinafter may be shown on a computer monitor or dedicated system display and/or it may be recorded for later reference or for analysis on digital media. Additionally, the wafer spatial distributions may be cross-correlated by referencing elliptical polarization data to correct for layer thickness variability and cross-calibrate with independent contamination characterization data obtained, for example, from total reflected X-ray fluorescence (TXRF), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like. These initial or corrected spatial distributions can then be compared to those from wafers known to be within specification to determine if the sample in question has any defective or problematic features, which require further testing. However, in general, it is desirable to use low cost SHGs and other methods of their use, calibration by or for slow and expensive direct methods, such as TXRF.

In determining what is an acceptable or unsatisfactory criteria for a wafer, human decision-making may initially be employed (e.g., in detecting a generated heat map 2400) until the tool is properly calibrated to be able to autonomously mark the wafer. For well-characterized processes in a wafer fab, human decisions need only be made based on the characteristics of the marked wafers to determine the root cause of any systematic problems in yield.

Regardless of how implemented, FIG. 10 provides a plot 2500 showing a first method embodiment herein that may be used to make such decisions. As with other methods discussed and shown below, this method relies on characterizing the SHG response with multiple shutter blocking events, where the interrogation laser is gated over a period of time.

In this first example, the section of the sample to be interrogated is charged to saturation (typically by a laser). In this example, a single source is used to generate the pump beam and the probe beam, but separate pump and probe sources may be used in other embodiments. During this time, the SHG signal may be monitored. By virtue of material characterization and/or observation of SHG signal intensity (I _ch ) The saturation level can be known. Upon (or after) saturation, electromagnetic radiation from the laser (pump beam) is blocked from the sample section. During a selected period of time (t _bl1 ) The laser (probe beam) is thus gated. After the gating is stopped, an SHG intensity measurement (I) is performed with the laser (probe beam) exposed to the surface _dch1 ) Thereby observing charge decay at a first discharge point. During a period of time (t _ch ) After recharging the material section to saturation (with the pump beam), at a time (t _bl2 ) A second blocking event occurs in order to identify another point along which a composite decay curve is to be formed. When the laser beam is unblocked (probe beam), the SHG signal intensity (I) is measured again _dchs2 ). This reduced signal indicates charge during the second gating event or blocking time intervalAttenuation. Again charged to saturation by the laser (pump beam), a third, different time blocking event (t _bl3 ) Subsequent SHG interrogation and signal strength measurements are then made and for a third measurement of charge decay relative to SHG strength (I _dch3 )。

Although in the above example the sample is charged to a saturation level, in other examples the sample may be charged to a charge level below saturation. Although in the above example, three blocking times t _bl1 、t _bl2 T _bl3 Is different, but in other examples, three blocking times t _bl1 、t _bl2 T _bl3 May be identical. In various examples, the sample may be initially charged to a charge level and SHG intensity measurements may be obtained at different time intervals after the initial charge event (I _dch1 )、(I _dch2 ) (I) _dch3 )。

As mentioned above, these three points (corresponding to I _dch1 、I _dch2 I _dch3 ) May be used to construct a composite charge decay curve, which is referred to herein as a "composite" curve in the sense that its components are from several related events. And while yet further iterations (possibly with different gating times to generate more decay curve data points, or using the same relational timing to confirm certainty and/or measurement removal errors from selected points) may be employed such that four or more block-then-detect cycles are employed, it should be observed that as few as two such cycles may be employed. While one attenuation-related data point will not provide meaningful attenuation curve characterization, a pair of lines from which a curve can be modeled or extrapolated to provide some utility will result in an approximation with better accuracy for three or more points of an exponential attenuation fit. In other words, any simple (e.g., not physically stretched by dispersion transport) decay kinetics has a general formula: measurable (t) =m ₀ * exp (-t/tau), thus in order to find two unknown parameters M ₀ And tau, assuming this simple dynamics, at least 2 points are required. In dispersive (i.e., nonlinear) dynamics, if n points are measured, it is desirable to measure as many points as possible to extract the (n-1) order correctionParameters, and then apply a model appropriate to the approximation order. Furthermore, the set of measurements will measure different electric fields (E) to make them truly practical and accurate with tau to assign them to a particular type of defect.

The above method can provide a parameter versus time (such as interface leakage current or occupied trap density versus time) dynamics by obtaining measurements at several time points. A time constant (τ) may be extracted from the parameter and time dynamics curve. The time constant may be attributed to the time constant characteristics of a particular type of defect.

In any case, the attenuation dependent data obtained may be preceded (as in the example) by SHG data acquisition while the material is saturated with interrogation (or detection) laser. However, the charge will not necessarily reach saturation (e.g., as mentioned above). No necessary measurements need to be made before blocking a/the charging laser. Furthermore, the charging will not necessarily be performed with an interrogation/detection laser (see, e.g., the pump/detection methodology referenced above).

In any event, after a target test at one sample site, the sample material is typically moved or indexed to locate another section for the same (or similar) test. In this way, several sections or even each section of sample material may be interrogated and quantified as the entire wafer is scanned, as discussed above.

Fig. 11 and plot 2600 illustrate an alternative method (or complementary method) of acquiring charge decay related data by scanning is shown in plot 2600. In this method, after the first/the first charge to saturation, the different SHG intensities (I _dch1 、I _dch2 、I _dch3 ) To study the time interval (t) between a plurality of blocks _bl1 、t _bl2 、t _bl3 ) A continuous (or at least semi-continuous) discharge within. The intensity and/or frequency of the laser pulses from the interrogation/detection laser is selected such that the average power of the interrogation/detection laser is reduced to avoid recharging the material between blocking intervals while still obtaining a reasonable SHG signal. For this purpose, as few as one to three laser pulses may be applied. Such asThis reduction (in number and/or power) may be ignored or accounted for by calibration and/or modeling considerations for material excitation by interrogation or detection laser pulses.

In various embodiments, a separate pump source may be used for charging. However, in some embodiments, the probe beam may be used to charge the sample.

In any case, the delay between pulses may be the same or tuned to account for the expected instantaneous charge decay profile or for other practical reasons. Likewise, while the delay is described in terms of "gating" or "blocking" above, it should be appreciated that one or more optical delay lines as discussed above in connection with FIG. 6C may be used to create the delay. Still further, the same applies to the blocking/gating discussed in association with fig. 10.

Further, as described above, the method in FIG. 11 may be practiced with various modifications to the number of blocking or delay times or events. Furthermore, the SHG signal may or may not be measured during charging to saturation. Regardless, the method in fig. 11 may be practiced (as shown) such that the final gating period causes the SHG signal to be null. Can be obtained by measuring the charging intensity (I _ch ) The method is repeated at the same site or confirmation of this is obtained by observing only the SHG signal when (re) charged to saturation.

Fig. 12A-12E are instructive as to the manner in which attenuation-related data points are obtained using target hardware. Fig. 12A provides a graph 2700 showing a series of laser pulses 2702, in which intermediate or alternating pulses are blocked by shutter hardware (e.g., as described above) in a so-called "pulse picking" method. During a given time interval, individual pulses may be passed (indicated by the solid line) and other pulses blocked (as indicated by the dashed line).

Fig. 12B provides a chart 2710 showing the manner in which the resolution of the blocking technique for SHG studies may be limited by the repetition (rep) rate of the detection laser. In particular, when presenting an attenuation curve similar to the attenuation curve 2712, a pulsed laser shown operating on the same timescale as in fig. 12A may be used to resolve the time delay profile with every other pulse blocked. However, a shorter curve 2714 cannot be resolved or observed under these circumstances. Thus, the use of an optical delay stage may provide additional utility.

Thus, the chart 2720 in fig. 12C shows (graphically and literally) how the overlapping useful area (in terms of decay time of the curve versus repetition rate of the laser) can be provided relative to a reference time block associated with charging the sample and introducing a delay, which also shows how it is feasible to have a short time span only when the delay stage is tolerant of interrogating the decay curve and a longer time span only when the pump and/or probe beam is blocked.

Fig. 12D and 12E further demonstrate the utility of the combined blocking/delaying apparatus. Graph 2730 shows an exemplary SHG signal generated by an individual laser pulse 2702. By means of a delay stage alone, only the range (X) between each such pulse can be interrogated by means of varying optical delays. In contrast, additional utility within a range (Y) may be achieved with systems that combine a delay stage and blocking or shutter means, such as a chopper, shutter, or modulator. As shown by graph 2740, such a system is capable of measuring decay curves (and their associated time constants) over a range of one to several pulse times.

Fig. 13 provides a plot 2800 illustrating a third method embodiment herein. This embodiment is similar to the embodiment of fig. 11, except that a laser (optionally used to monitor or capture its SHG intensity (I _ch ) Signal) or other electromagnetic radiation source charges the material and then blocks or otherwise stops application of laser radiation to the sample, allowing for a time interval (e.g., t _i ＝t ₀ 、2t ₀ 、3t ₀ 、7t ₀ 、10t ₀ 、20t ₀ 、30t ₀ 、70t ₀ Essentially according to a logarithmic time scale and linear time, where t ₀ Is about 10 at the beginning of measurement ^-6 sec or 10 ^-3 The scale parameter of sec) measures the discharge current (J _dch1 、J _dch2 、J _dch3 ). The method gives the one after decay of the e-h plasma in the substrate and when the discharge current is seen initiallyAn estimate of the lifetime of mobile carriers in the etched substrate is provided to provide important physical parameters of the wafer. And after determining the carrier lifetime, the discharge of the current can be interpreted in its time dependence (i.e., its dynamics with respect to charge decay) in the same way as it was obtained by SHG sensing of the discharged charge.

Embodiments may be used to measure a time constant having a range of values (e.g., for decay). For example, the time constant may be in a range of between 0.1 and 1 femtosecond, between 1 and 10 femtoseconds, between 10 and 100 femtoseconds, between 100 and 1 picosecond, between 1 and 10 picoseconds, between 10 and 100 picoseconds, between 100 picoseconds and 1 nanosecond, between 1 and 10 nanoseconds, between 10 and 100 nanoseconds, between 100 and 1 microsecond, between 1 and 100 microseconds, between 100 and 1 millisecond, between 1 and 100 milliseconds, between 100 and 1 second, between 1 and 10 seconds, or between 10 and 100 seconds or more. Likewise, the time delay (Δ) between the probe and the pump (or pump and probe) may be, for example, between 0.1 and 1 femtosecond, between 1 and 10 femtoseconds, between 10 and 100 femtoseconds, between 100 and 1 picosecond, between 1 picosecond and 10 picoseconds, between 10 picoseconds and 100 picoseconds, between 100 picoseconds and 1 nanosecond, between 1 and 10 nanoseconds, between 10 nanoseconds and 100 nanoseconds, between 100 nanoseconds and 1 microsecond, between 1 nanosecond and 100 microseconds, between 1 microsecond and 100 microseconds, between 100 microseconds and 1 millisecond, between 1 microsecond and 100 milliseconds, between 100 microseconds and 1 second, between 1 second and 10 seconds, between 10 seconds and 100 seconds. Values outside these ranges are also possible.

Various physical methods may be employed in providing a system suitable for carrying out the method in fig. 13 (notably, the method may be modified as those described above). Two such methods are shown in fig. 14A and 14B.

The systems 2900 and 2900' use gate electrodes 2910 and 2920, respectively, made of missile materials that are transparent in the visible range. Such an electrode may touch the wafer 2020 to be inspected, but is not required as they may be separated by only a minimum distance. In various embodiments, the electric field in the dielectric may be estimated by extracting electrode-dielectric-substrate structural parameters using AC measurements of capacitance-voltage curves (CV curves). CV curve measurements may be accomplished by using standard CV measurement settings available on the market connected to material samples in the target tool (e.g., an applied voltage will provide an electric field in the dielectric of between about 0.1MV/cm and about 5 MV/cm). The wafer may be held on an electrically conductive chuck 2030 that provides electrical substrate contact. Another alternative construction of a gate electrode would be an ultra-thin Au or Al film on 10A to 30A thick glass, which may reduce sensitivity due to the absorption of some photons by the thin semi-transparent metal layer.

However, the electrodes 2910 and 2920 do not have significant absorption problems (although some refraction-based considerations may occur, they may be calibrated or may be otherwise considered in the system). Such electrodes may include a transparent conductor gate layer 2930 (made of a material such as ZnO, snO, or the like) connected to an electrical contact 2932. An anti-reflective top coat 2934 may be included in the construction. As shown, the gate layer 2930 may be set to be formed of a material having a thickness (D _gc ) Dielectric (SiO) ₂ ) And a transparent carrier 2936 is formed. In various embodiments, the transparent carrier includes an insulator that serves as a gate for a non-contact electrode that can employ, for example, capacitive coupling to perform electrical measurements similar to those described in section IV of U.S. provisional application Ser. No. 61/980,860 entitled "FIELD-BIASED SHG METROLOGY," filed on U.S. provisional application Ser. No. 61/980,860 entitled "WAFER METROLOGY TECHNOLOGIES," filed on month 4. Upon charging the wafer from the incoming laser radiation, the electric field across one or more of the wafer's interfaces will change, and the layers of the wafer should be capacitively coupled like a plate capacitor and plates in the electrodes. The charging of the electrode will involve movement of charge carriers to be measured as current.

D _gc Will be calibrated by measuring the CV curve on the semiconductor substrate by a non-invasive method and used in the electric field (E) calculation when the applied voltage is known. A negligible gap distance between the gate and the sample may be a gas gap. Alternatively, the electrodes may be in direct contact with the sample, rather than separated by an air gap or dielectric. Thus, a normal CV or IV amount may be performed in various embodimentsAnd (5) measuring.

Or given wafer and SiO ₂ A near index match between them, filling the gap with deionized water can help reduce boundary layer reflection without any adverse effects (or at least one adverse effect that cannot be resolved). Deionized (or clean room grade) water can maintain cleanliness around electrically sensitive and chemically pure substrate wafers. In fact, deionized water is less conductive than ordinary water.

In fig. 14B, a related construction is shown, except for the architecture of the carrier or gate holder 2938, where it is configured as a ring, as produced using MEMS technology, optimally formed from material etched away in the center and left near the periphery of the electrode. In any event, however, because of the large unoccupied area through which laser and SHG radiation must pass, it may be particularly desirable to fill that area with DI water as described above.

Regardless, throughout the electrode 2910, 2920 configuration, the embodiments are generally stationary relative to radiation that excites the material in use. The electrode structures may be stacked by a robotic arm or carrier assembly (not shown) before and after use.

As described above, in various embodiments, the electrodes directly contact the wafer to perform electrical measurements (such as measuring current). However, non-contact methods of measuring current may also be used, such as, for example, using electrodes capacitively coupled to the sample.

The systems and methods described herein may be used to characterize a sample (e.g., a semiconductor wafer or a portion thereof). For example, the systems and methods described herein may be used to detect defects or contaminants in a sample as discussed above. The systems and methods described herein may be configured to characterize a sample during the manufacture or production of a semiconductor wafer. Thus, the system and method may be used along a semiconductor manufacturing line in a semiconductor manufacturing facility. The systems and methods described herein may be integrated with a semiconductor manufacturing/production line. The systems and methods described herein may be integrated into a semiconductor wafer fab having automated wafer handling capabilities. For example, the system may be equipped with an Equipment Front End Module (EFEM) that accepts the attachment of a wafer cassette, such as a Front Opening Unified Pod (FOUP). Each of these cassettes may be delivered to the machine by a human operator or by an automated cassette handling robot that moves the cassette along the manufacturing/production line between processes.

In various embodiments, the system may be configured such that once the cassette is mounted on the EFEM, the FOUP is opened and a robotic arm selects individual wafers from the FOUP and moves them through automatically actuated doors included in the system, into an opaque process box, and onto vacuum chucks with bias capability. The chuck may be designed to fit complementarily with the robotic arm so that it can place the sample on top. At some point in the process, the wafer may be held over a scanner to identify its unique laser mark.

Part III

Fig. 15A and 15B show suitable hardware for use in the SHG systems and methods as further described in section I entitled "PUMP AND PROBE TYPE SHG METROLOGY" of U.S. provisional application No. 61/980,860 entitled "WAFER METROLOGY TECHNOLOGIES" filed on 4 months 17 in 2014. Other system and method options are presented in section II of U.S. provisional application No. 61/980,860 entitled "CHARGE DECAY measure SYSTEMS AND METHODS," filed on 4/17, entitled "WAFER METROLOGY TECHNOLOGIES," for example, with respect to intermediate optics, including optical delay lines, and optional electrode features.

As shown, the system 3000 includes a main or probe laser 3010 for directing an interrogation beam 3012 of electromagnetic radiation toward a sample wafer 3020 held by a vacuum chuck 3030. As shown in fig. 15B, chuck 3030 includes or is set on an x-stage and a y-stage, as well as a rotational stage for positioning a sample location 3022 across the wafer relative to where the laser is aimed, as desired. The x-y stage enables scanning of multiple wafer surface sites or locations 3022 without moving other hardware. A rotary stage optionally enables evaluation of the crystal structure effect on SHG. Further optional features, aspects, and/or uses of chuck 3030 are presented elsewhere in the application as authorized. Sample site 3022 may comprise one or more layers. Sample site 3022 may include a composite substrate comprising at least two layers. Sample site 3022 may comprise an interface between two different materials (e.g., between two different semiconductor materials, between two differently doped semiconductor materials, between a semiconductor and an oxide, between a semiconductor and a dielectric material, between a semiconductor and a metal or an oxide and a metal).

When the system 3000 is in use, the beam 3014 of reflected radiation directed at a detector 3040 will contain an SHG signal. The detector 3040 may be any one of a photomultiplier tube, a CCD camera, a burst detector, a photodiode detector, a high-speed scanning camera, and a silicon detector. The system 3000 may also include one or more shutter-type devices 3050. The type of shutter hardware used will depend on the time frame in which the laser radiation will be blocked, dumped or otherwise directed away from sample site 3022. An electro-optical blocking device, such as a pockels cell or kerr cell, may be used to obtain very short blocking periods (i.e., having a blocking period of about 10 ^-9 Second to 10 ^-12 Actuation time in seconds).

For longer blocking time intervals (e.g., from about 10 ^-5 Seconds and above), a mechanical shutter or flywheel chopper type device may be employed. However, the electro-optic blocking device will allow a wider range of materials to be tested according to the following method. A photon counting system 3044 capable of discretely gating very small time intervals (typically on the order of picoseconds to microseconds) may be employed to resolve the time dependent signal counts. For faster time frames, optics may be incorporated as described above A delay line.

System 3000 may comprise an additional electromagnetic radiation source 3060 (also referred to as a pump source). In various implementations, the radiation source 3060 may be a UV flash lamp shown emitting laser light of a directed beam 3062 or emitting a divergent or optically collimated pulse 3064. In the case of a laser source, its beam 3062 may be collinear with beam 3012 (e.g., as directed by an additional mirror or prism, etc.). The wavelength of light output by source 3060 can be anywhere from between about 80nm and about 1000 nm. With shorter wavelengths in this range (e.g., less than about 450 nm), charge excitation may be driven with fewer photons and/or with lower peak intensities than longer wavelengths.

For a flash lamp, the energy per flash or the power level during the flash may be substrate material dependent. A flash lamp that produces a total energy of 1J to 10kJ per flash would be suitable for fully depleted silicon on insulator (FD-SOI). However, a pulsed or constant UV source is also possible. An important factor in pump performance and use is the injection of charge carriers into the dielectric of the material to be interrogated. Manufacturers of suitable flashlights include Hellma USA, inc. and Hamamatsu Photonics K.K.

When a laser is employed as source 3060, it may be any one of a nanosecond, picosecond, or femtosecond or faster pulsed laser source, which may even be a continuous solid state laser. In various embodiments, the pump source is tunable in wavelength. Commercial options for tunable lasers include the Velocity and Vortex tunable lasers of Spectra Physics. Additional tunable solid state solutions are available from solid state lasers of the LT-22xx series of LOTIS ltd.

Whether provided as a laser or a flash lamp, the pump source 3060 may be selected for relatively high average power. This may be from about 10mW to about 10W, but more typically from about 100mW to about 4W, depending on the material to be interrogated (again, this consideration ensures that the charge carrier mobility is induced in such a way that the charge carriers are injected into the interface of the material (e.g., dielectric interface), which may be material specific). The average power of pump source 3060 is selected to be below the optical damage threshold of the material. For example, when the interrogation material comprises silicon, pump 3060 may be selected to have an average optical power between 1W and 2W so as not to exceed the optical damage threshold of silicon.

The detection laser 3010 may be any one of a nanosecond, picosecond, or femtosecond or faster pulsed laser source. Two options currently available on lasers with the required peak power, wavelength and reliability are doped fiber and Ti: sapphire cells. The Coherent's VITESSE and Spectra Physics MAI TAI laser is an example of a suitable Ti: sapphire device. Other related Ti: sapphire devices are also manufactured by femto assers Gmbh and other manufacturers. Suitable doped fiber lasers are produced by IMRA, onetelevision and Toptica Photonics. Picosecond and/or nanosecond lasers from many manufacturers (such as Hamamatsu) may also be an option depending on the substrate material and pump type. The laser 3010 may operate in a wavelength range between about 100nm and about 2000nm, with a peak power between about 10kW and 1GW, but deliver power that averages less than about 150 mW.

Various other optional so-called "intermediate" optical components may be employed in the system 3000. For example, system 3000 may include a dichroic reflective or refractive filter 3070 for selectively transmitting an SHG signal coaxial with reflected radiation directly from laser 3010 and/or source 3060. Alternatively, a prism may be employed to distinguish weaker SHG signals from the most strongly reflected main beam. However, a dichroic system as mentioned above may be preferred, as the prismatic approach has proven to be very sensitive to misalignment. Other options include the use of diffraction gratings or a thin film beam splitter. A beam 3080 for focusing and collimating/column optics may be provided. Alternatively, a filter wheel 3090, polarizer 3092, and/or zoom lens 3094 unit or assembly may be employed in the system. Furthermore, an angular (or arc) rotation adjustment (with corresponding adjustment for the detector) and on-line optics may be required.

The output from the detector 3040 and/or photon counting system 3044 may be input to an electronic device 3048. The electronic device 3048 may be a computing device, a computer, a tablet computer, a microcontroller, or an FPGA. The electronic device 3048 includes a processor that may be configured to execute one or more software modules. Removal of In addition to executing an operating system, the processor may be configured to execute one or more software applications (including a web browser, a telephone application, an email program, or any other software application). The electronic device 3048 may implement the methods discussed herein by executing instructions contained in a machine-readable non-transitory storage medium, such as a RAM, ROM, EEPROM or the like. The electronic device 3048 may include a display apparatus and/or a graphical user interface to interact with a user. The electronic device 3048 may communicate with one or more devices via a network interface. The network interface may include a communicable transmitter, receiver, and/or transceiver, such as, for example, a wired ethernet network,Or a wireless connection.

With respect to other options, it is desirable to improve the signal-to-noise ratio of the SHG count because a SHG signal is weaker than the reflected beam from which it is generated. As the photon count gating time for the photon counting system 3044 is reduced for the blocking and/or delaying processes described herein, the improvement becomes more important. The noise reduction method that can be used is to actively cool the photon counter. This can be accomplished using cryogenic fluids such as liquid nitrogen or helium or through solid state cooling using a Peltier device. Other areas of improvement may include the use of Marx Bank Circuits (MBCs) as related to shutter speed. In addition, the system 3000 can be incorporated online within a production environment. The process line components before or after the system 100 may include any of an epitaxial growth system, a lithography and/or deposition (CVD, PVD, sputtering, etc.) system.

In any event, fig. 16A and 16B provide views of a first set of dedicated chuck hardware that may be employed in the target SHG system. Chuck 3030 holds a wafer 3020 by vacuum or other means thereto. Chuck 3030 is electrically conductive and is connected to a power supply. Optionally, a capacitive coupling probe 3100 is also connected to the power supply 3120. The power supply may be computer controlled, or at least its output coordinated by the computer for timing reasons as outlined above. The probe 3100 can also be controlled and/or monitored in the sense that it will be part of a capacitive circuit attached to the power supply 3120, which can be monitored along with the chuck 3030 by a voltmeter to ensure that the voltage is induced as desired.

The probe 3100 includes an aperture 3102 or port (e.g., 0.2mm in diameter) in its ring 3104 to allow the light beams 3012, 3014 (interrogation beam and reflected SHG beam) to pass unobstructed through and to be fixed relative to the optics so that it moves or stays with the optics to remain centered on the (re) positioned sample site 3022 as the device surface is scanned. The coupling (indicated as having a positive "+" charge) is located near the sample device surface (e.g., within about 1mm to about 2 mm) but does not contact, which is supported by a cantilever or otherwise. The probe 3100 may be provided as a ring 3104 as shown in fig. 16B, or it may comprise a larger disk or plate.

With respect to the example shown in the cross-section of FIG. 16B, a wafer 3020 or device surface (including silicon) is formed by an insulator SiO ₂ Separated from the bulk layer of the silicon block. Thus, as explained above, it is desirable to inductively bias the device surface because it is otherwise (or at least substantially) electrically isolated or isolated from the underlying silicon contacting the conductive chuck 3030.

Fig. 17A-17C detail an electromagnetic chuck 3030 including an electrical coil 3130 connected to a power supply 3120. In use, wafer 3020 sits and is secured on top of chuck 3030. When an Alternating Current (AC) is applied to the coil 3130, this generates an alternating magnetic field across the wafer 3020. The magnetic field induces a potential across the wafer 3020 including its device surface. This electric field then implements the various modes of SHG interrogation mentioned above (some of which are described in more detail below). Alternatively, a DC current may be applied to the coil 3130 oriented parallel to the chuck 3030, creating a constant magnetic field across the chuck to achieve other effects as described above.

Fig. 18A shows an example AC voltage (V) profile (sine wave) applied to a bulk layer of a substrate over time. Fig. 18B shows the induced voltage (V) between the device and the bulk layer of the substrate on which the device is fabricated _i ) Is a hypothetical response of (1). In various embodiments, the substrate mayIncluding a silicon wafer or a portion of a semiconductor material. Fig. 19A shows an example AC voltage (V _o ) Profile (square wave). Fig. 19B shows the induced voltage (V _i ) Is a hypothetical response of (1). Notably, the voltage input in either of fig. 18A or 19A may be different than shown, and may potentially be applied in a step, ramp, sine wave, or other form.

More specifically, with respect to fig. 18A and 18B, as mentioned above, multiple photon counting windows may be required to minimize noise and obtain a statistically relevant indicator of SHG intensity that varies as a function of voltage across the interface. For this purpose, example points A1 and A2 are timed such that the voltage between the bulk and the device layer (voltage A) is the same for both points. The same applies for example points B1 and B2 at voltage B and example points C1 and C2 at voltage C. Using voltage A as an example, SHG is recorded, and the count at point A1 can be as high as A3, A4, A at point A2 and further in any long series depending on the desired measurement time _n The counts at … are summed. The total number of counts measured during this period of time is then divided by the time this "gating" spans as a way to find the average number of counts per second so that the SHG intensity can be plotted as a function of bulk-device voltage a. The same method can be used to obtain B3, B4, B at points B1 and B2 and in any long series depending on the desired measurement time _n A measurement of voltage B at …. The total number of counts measured during this period of time is then divided by the time this "gating" spans as a way to find the average number of counts per second so that the SHG intensity can be plotted as a function of bulk-device voltage B. Likewise, this method can be used to obtain C3, C4, C at points C1 and C2 and in any long series depending on the desired measurement time _n A measurement of voltage C at …. The total number of counts measured during this period of time is then divided by the time this "gating" spans as a way to find the average number of counts per second so that the SHG intensity can be plotted as a function of the bulk-device voltage C. Further details regarding the utility of SHG strength as a function of bias voltage can be found in the DC bias literatureExamples of DC bias literature are found in "Charge Trapping in Irradiated SOI Wafers Measured by Second Harmonic Generation", IEEE journal of nuclear science, vol.51, no.6.Dec.2004 and "Optical probing of a silicon integrated circuit using electric-field-induced second-harmonic generation", applied physical bulletin 88,114107, (2006), the entire disclosure of each of which is incorporated herein by reference.

More specifically, with respect to FIGS. 19A and 19B, examples of methods for interrogating a silicon-on-insulator (SOI) device are shown. In this example, a conductive chuck starts in a "neutral" ground state, and the bulk and device layers are at an equilibrium potential. At time "a", the voltage applied to the chuck is rapidly changed to apply the voltage to the conductive bulk layer of the sample. Since the device layer of the sample is separated from the bulk by a thin buried oxide layer and is not in direct contact with a conductor, a potential field or voltage will be induced between the device and bulk layers. Between times "a" and "B", the voltage applied to the chuck is unchanged. Since the dielectric between the bulk and the device layer is not perfect, the induced potential will drive a leakage current between the layers, causing the potential between the bulk and the device layer to return to its natural state. This spike and decay in the electric field is then monitored via the SHG to provide insight into leakage current. At time "B", the voltage applied to the chuck returns to ground, causing a reversal of the voltage across the interface.

As described above, each of chapters I, II, III, and IV of U.S. provisional application No. 61/980,860, entitled "WAFER METROLOGY TECHNOLOGIES," filed on month 4, 17, 2014, is incorporated by reference herein in its entirety. Similarly, the entire disclosures of (i) U.S. patent application Ser. No. 14/690,179 published as U.S. publication No. 2015/0330908, (ii) U.S. patent application Ser. No. 14/690,256 published as U.S. publication No. 2015/0331029, and (iii) U.S. patent application Ser. No. 14/690251 published as U.S. publication No. 2015/0331036, each of which is incorporated herein by reference, as if the patent application in the application was filed (i) at 5, 4, 17, entitled "Pump and Probe Type Second harmonic generation Metrology". PCT application No. PCT/US2015/026263, entitled "WAFER METROLOGY TECHNOLOGIES", filed on 4 months 16 in 2015, is also incorporated herein by reference in its entirety. Thus, features from the disclosure of any of these documents incorporated by reference may be combined with any of the features recited elsewhere herein.

Sizing using second harmonic generation

Semiconductor metrology may include a "critical dimension" of a metrology device. For example, these critical dimensions may include measuring the width, length and/or depth of a transistor or memory cell, the thickness of a gate oxide, or the diameter of a contact hole (via) through an interlayer dielectric layer. Small variations in any of these dimensions due to manufacturing process variations can result in poorly functioning or inoperable devices. Thus, in some cases, it may be useful to monitor such dimensions during manufacturing to prevent yield or performance problems. Monitoring the fabrication process early in device fabrication may be particularly advantageous. For example, it may take weeks to manufacture a complete semiconductor product; if defects early in the manufacturing process are not detected until the final test, all products produced during this period are at risk of defects. Thus, it may be advantageous to monitor the early stages of the production process: early missing of an error can result in the loss of millions of parts.

Techniques for measuring the dimensions of devices early in the production process include methods based on light beams and electron beams. Two methods for production monitoring of critical device dimensions include critical dimension scanning electron microscopy (CD-SEM) and Optical Critical Dimension (OCD) tools. CD-SEM is a scanning electron microscope specifically designed for measuring Critical Dimensions (CD) of semiconductor electronic devices; optical CD tools (OCDs) use light scattering from the surface of a semiconductor wafer containing the device to monitor changes in device dimensions as the device is manufactured. Additional tools that are not often used include Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM). Each tool has advantages and disadvantages.

The reduced size of the device may benefit from increasing the accuracy of the metrology tools used to monitor the production process. In addition, three-dimensional (3D) geometries are now used, which make it more difficult to measure and monitor production processes. These 3D geometries include finfets, surrounding gates, and nanowires for transistor geometries. NAND memory devices are now being produced, with many device layers vertically stacked; such devices benefit from metrology of the entire stack including features buried below the surface. The shrinking size and introduction of 3D complex geometries can be a challenge to current metrology tools.

Ideally, a metrology tool is sensitive, accurate, repeatable, reliable, and fast. Sensitivity is how small a change can be detected: can the metering tool detect a 5% dimensional change? For ten nanometer features, metrology tools may benefit from detecting a sub-nanometer dimensional change. The accuracy may be different from the sensitivity: is the gauge tool to be able to discern different changes? A metrology tool may present problems if it is unable to distinguish between different variations (e.g., between the width at the top and the width at the bottom of a feature). If many different geometry changes produce the same result, it may be difficult to monitor the process using the tool due to ambiguities in the cause of the metrology changes. Sensitive tools that lack precision can cause alarms of program variations, many of which are not important. Alternatively, it may be advantageous for a metrology tool to independently measure different important parameters of a device, such that there is a one-to-one correlation between a measurement and a geometry change.

Repeatability is different from sensitivity or accuracy. To monitor a production process, the variations introduced by the metrology tool may advantageously be much smaller than the variations in the process to be detected. It may be disadvantageous to have a tool that produces a different result over time that is comparable to or greater than the variation in the monitored device. The metrology tool may have drift over time due to changing environmental conditions (temperature, etc.) or internal components (contamination on the lens, etc.). In contrast, it would be advantageous for the metrology tool to be highly repeatable, giving the same results for the same feature size.

Repeatability, sensitivity, and accuracy can compete with one another in a metrology tool. For example, a tool that always produces the same result independent of device geometry will have perfect repeatability but lack any sensitivity. Tools that can detect any changes may be too sensitive to insignificant changes, i.e., lack of precision and repeatability. Useful tools can detect and identify important process variations and filter out insignificant process variations, indicating that insignificant process variations become important. These requirements may change over time as manufacturing processes become more mature or new programs are introduced. Thus, some flexibility of the metrology tool may be useful.

Cost of ownership can also be an important consideration in metrology tools used in production. In addition to the initial cost, capital expense, of the tool, there is also the cost of maintaining the tool (including preventive maintenance and repair). The lifetime of the tool is important: whether the tool is useful for one generation of products only, or whether it can be used for several generations of products? Another cost factor is the throughput of the tool: how fast is it measured? If the tool is too slow, many tools may be required, multiplying costs. A useful tool can advantageously be kept synchronized with the production line. In some cases, for example, if a production line can process sixty silicon wafers per hour, a metrology tool can measure sixty wafers per hour. Lower throughput may slow down the production process or fail to provide complete metering results; faster throughput will not speed up the production line and is therefore generally not necessarily required.

The other two components of the cost of ownership are the time of part failure and the result obtained. If the metrology tool damages the inspected parts such that they must be scrapped, this increases the cost of the tool. Each scrapped part adds to the cost of the tool and can significantly increase the cost of ownership, especially for high volume production. The time to obtain the result depends on the indirect cost of detecting the rate of production change. A metrology tool may be more valuable if it can detect a change in minutes while another tool takes hours. During the time between when a process change occurs and when the process change is corrected, bad parts can be manufactured. Such bad parts may be scrapped and thus increase the cost of the metrology tool. Thus, it may be advantageous to obtain results quickly to reduce or minimize production losses (i.e., maintain or increase yield).

Current metrology tools for semiconductor device monitoring can vary significantly in such properties as sensitivity, accuracy, repeatability, reliability, speed, non-destructive evaluation, and cost. For example, a TEM (transmission electron microscope) is very sensitive and accurate, enabling measurements of less than a tenth of a nanometer on a single transistor; however, it may involve removing a section of the device, which may destroy the sample. TEM analysis also involves an expensive tool, a rich operator, and a relatively long time (hours or perhaps even days) to obtain results. Thus, a TEM, while very accurate and sensitive, may not be used as an "in-line" monitor or as a direct part of a production line.

Two common tools used in the production of advanced semiconductor integrated circuits are CD-SEM and optical CD. CD-SEM can capture a direct, top-down image of a device. The resulting image may be used to make measurements of the dimensions of a device. If there are many devices in an image, many measurements can be made, improving the sensitivity of the measurements by averaging. CD-SEM provides a simple, direct measurement, but they have measurement errors that can cause problems. In particular, charging the device due to electron bombardment can cause imaging distortion that leads to metrology errors. Electron bombardment can also contaminate the device, resulting in varying dimensions that reduce accuracy. For example, devices that initially exhibit a width of ten nanometers may appear to increase to twelve nanometers due to contamination. Furthermore, CD-SEM is generally less fast than optical tools and is a more complex tool, resulting in a higher cost of ownership.

An optical critical dimension metrology tool (OCD) can provide a fast, non-destructive method for measuring critical dimensions of a device; however, they can be challenged by smaller geometries and 3D structures. The wavelengths of light used may be in the visible, ultraviolet (UV), or Infrared (IR) portions of the spectrum. Such optical wavelengths may range from about two hundred nanometers to over one thousand nanometers, and may be much longer than the measured device dimensions (which may currently range from one nanometer to one hundred nanometers). Sensitivity can thus be a problem for such tools. Furthermore, since they do not measure an image directly, it may be difficult to distinguish between measurement variations and the root cause of the variations-the accuracy problem. Furthermore, OCD tools average many devices (hundreds or thousands of devices) together into a single measurement. This improves measurement accuracy and sensitivity, but introduces usage limitations. OCD tools are not capable of measuring individual devices as measured by CD-SEM or TEM; OCD tools have large sample areas measured in tens or hundreds of microns and are therefore typically used only on large pieces of the same device (test structure or memory array). Furthermore, this is a disadvantage compared to CD-SEM tools, which can measure individual devices or small areas. On the other hand, OCD tools are fast and relatively reliable and do not damage the sample. Therefore, OCD tools are used to monitor the production of many types of semiconductor devices.

Unfortunately, OCD tools have increasing difficulty maintaining the required precision and sensitivity as device sizes shrink and geometries become 3D and more complex. The seed way to compensate for smaller feature sizes is to reduce the wavelength of light used in OCDs—from visible to UV; however, UV light may be less able to penetrate into 3D structures, especially as used in NAND memory devices. Although silicon is transparent at IR wavelengths, it is opaque at visible or UV wavelengths, making metering of buried structures difficult or impossible. Buried structures can be measured using IR light, but are less sensitive to small dimensional changes due to the long wavelength of the light.

Small angle x-ray scattering (SAXS) has been proposed and tools are being developed using this technique. X-rays have the advantage of very short wavelengths (typically less than one nanometer), so they can be measured very accurately; however, x-rays can have significant drawbacks for a production tool. First, x-rays may involve complex and expensive equipment to generate, focus, and detect, as compared to OCDs. Second, x-rays can cause damage to the electronic device, thereby making the electronic device uncertain for production use. Third, in some cases, x-rays may be measured slower than OCDs or CD-SEM. Because of these factors, it is not clear whether SAXS can be used as a surrogate for OCD or CD-SEM. Thus, there is a current and growing need for new technologies that extend or replace current in-line production metrology tools.

To address some of the difficulties associated with performing metrology on semiconductor devices with increased complexity and reduced size (e.g., semiconductor devices at various stages of production), new dimension metrology systems and methods are disclosed herein that are based on light-based second harmonic generation (also referred to herein as SHG-CD, denoted Second Harmonic Generation-Critical Dimension (second harmonic generation-critical dimension)).

Second Harmonic Generation (SHG) is a nonlinear optical phenomenon in which light of one frequency (e.g., pulses of light) impinges on a sample and generates light of twice the frequency (referred to herein as SHG light, SHG signal, SHG light, or second harmonic generated light). Additional information regarding second harmonic generation is described above and provided, for example, in U.S. patent 10,591,525 to Koldiaev et al, entitled "Wafer Metrology Technologies," which is incorporated herein by reference in its entirety, at 17, 3, 2020. Second harmonic generation typically involves a non-centrosymmetric material, an interface, or a defect: breaking an inversion symmetry of the sample (e.g., at a point or in an area where interaction with incident light occurs). In centrosymmetric materials, such as silicon, second harmonic generation occurs at interfaces and defects where inversion symmetry is broken. Second harmonic generation may be enhanced by an electrostatic field (DC) at the interface or defect. These electrostatic fields may be generated by an interface between different materials, a Space Charge Region (SCR), doping, or defects. The resulting "electric field induced second harmonic generation" EFISHG of light can be used to detect electronic properties of the sample (such as buried interfaces and electron states at defects, including band bending, state density, charge and adsorption atomic adsorption).

In addition, small variations in the physical characteristics of a semiconductor device can create large variations in the internal electric field in the device. The change in the electric field inside the sample caused by the dimensional change of the device in turn alters the second harmonic generation of the light in the sample. Similarly, this effect may also be referred to as electric field-induced second harmonic generation of light, or EFISHG.

A second harmonic generation system (also known as a SHG-CD system) for determining critical dimensions may illuminate a sample, a structure, and/or a device (e.g., an electronic device) and use SHG light emitted by the device to determine the corresponding physical structure (e.g., shape and/or size) of the device and/or to monitor changes in such features. In some cases, SHG-CD systems may use SHG light emitted by devices produced in a production line to monitor the quality and stability of the production process, and possibly improve the yield and/or performance of the produced devices. The devices measured by the SHG-CD system may or may not have been completed and the changes may be unplanned changes (e.g., changes associated with a process tool, changes associated with degradation, environmental changes, failures, changes in consumables used by the process tool, and the like). In some cases, SHG-CD systems may use SHG light emitted by a sample, device, and/or structure to determine one or more material properties of the sample, device, and/or structure. In some cases, SHG-CD systems may use SHG light emitted by a sample, device, and/or structure to determine both geometric and material properties of a sample, device, and/or structure.

SHG-CD systems may be more sensitive to small local changes in three-dimensional geometry than other non-destructive techniques (such as OCD or CD-SEM), and may reduce or eliminate the need for destructive production monitoring (such as cross-sectional TEM or SEM or x-ray analysis). SHG-CD systems may be faster than electron beam or x-ray techniques and may reduce the cost of sample monitoring (e.g., in a production line).

In addition to or as an alternative to monitoring changes in physical characteristics (e.g., shape and/or size) of the device or portions thereof and thus monitoring production, the SHG-CD system may provide feedback signals, feedback data, or information that may be used to control the production steps of the device. In some cases, the feedback signal, feedback data, or information may be used to control the production step in which the monitored sample is produced. In some cases, the SHG-CD system may be included in a sample evaluation step and may provide a feedback signal or feedback data to a step before or upstream of the evaluation step. For example, this previous step in the manufacturing process may include a lithography, etching, or deposition step. In some embodiments, the SHG-CD may provide a feed-forward signal, feed-forward data, or feed-forward information that may be used to control a production step after a monitoring step or sample measurement. In some such implementations, subsequent or downstream steps may be adjusted based at least in part on the feedforward signal, feedforward data, and/or feedforward information provided by the SHG-CD to adjust or correct for manufacturing process variations detected by the SHG-CD system.

In some examples, the SHG-CD system directs light, such as pulsed light (e.g., pulsed laser light), onto a sample, such as a silicon wafer comprising semiconductor devices or partially-structured semiconductor devices. SHG-CD can be used to monitor a sample at some point in the semiconductor manufacturing process by directing light toward the sample and detecting the resulting SHG light (also known as the SHG signal). The pulses of incident light may generate light at a second harmonic (or half wavelength) of the incident light, sometimes referred to as a Second Harmonic Generation (SHG) signal and/or SHG light. One or more detectors may be used to measure the SHG signal. The detectors may be configured to measure one or more of intensity, angular distribution, or polarization of the SHG signal by generating a detected SHG signal (e.g., an electronic signal), or any combination thereof. In some cases, the detected SHG signal may be proportional to the intensity of SHG light incident on the detector (e.g., on an optoelectronic sensor of the detector). Additionally, the incident light pulse may be adjusted to improve (e.g., increase) the SHG signal from the sample, such as by selecting polarization, wavelength, or intensity. In addition, the orientation of the sample may be adjusted, such as by rotating the sample relative to the scattering plane of light (e.g., a plane formed by an incident beam and an axis perpendicular to the sample surface).

In some cases, the sample may be prepared for second harmonic generation measurements by exposure to a secondary beam of light or charge. For example, the region of the sample from which SHG light is emitted may be optically pumped by directing a secondary or auxiliary beam of light onto the region. The secondary or auxiliary light beam may have the same or a different wavelength than the primary light beam incident on the sample (the pulse used to generate the SHG signal). For example, the charge may be from a corona discharge. Some examples of optical pumping using an auxiliary light source and example configurations for providing charge are discussed above. However, there is no need to provide optical pumping and/or electronic charge accumulation or deposition and thus the SHG-CD need not include a light source for optical pumping in addition to the detection light source.

In various systems and methods, the SHG signal may be monitored for changes (e.g., changes associated with intensity, polarization, spatial distribution, etc.) in the SHG signal that may be indicative of changes in the production of the semiconductor device (e.g., changes in one or more processes prior to metrology). Such variations in the production of semiconductor devices can produce variations in device geometry characteristics, such as variations in device dimensions (e.g., width, length, height, thickness), such as the width of transistor features, or alignment or spacing between features. Such variations in geometric features may also include variations in shape. In some cases, the SHG signal and/or the detected SHG signal may be processed (in the optical or electronic domain) to make changes in the SHG signal and/or the detected SHG signal more pronounced. In some embodiments, the SHG signal may be used to alert manufacturing personnel or equipment to potential problems with production. In some embodiments, the SHG signal or detected SHG signal may be used to provide feedback to production equipment early in or upstream of the production process to improve device yield or performance. In some embodiments, the SHG signal or detected SHG signal may be used to provide feed forward to subsequent or downstream steps of the production process to correct for previous changes.

In some cases, the change or variation in the geometric feature of the sample or device may include a difference between the geometric feature of the sample or device and a saved geometric feature stored in a memory of the system. In some examples, the saved geometric features may include reference geometric features (e.g., provided by a user), or geometric features previously determined by the SHG-CD system.

In some examples, the SHG signal may be used to determine the geometry or electronic structure of a feature of a fabricated device. The device may be a finished product or at some early stage of production. The SHG signal may be compared to a database of (e.g., geometric) features to determine the structure of the device (e.g., geometric) features. In some cases, the SHG signal may be compared to a database of (e.g., material properties) features to determine the electronic structure (e.g., material properties) of the device. The SHG signal may also be used to calculate a structure based on a priori knowledge of the structure (e.g., geometry). A database of (e.g., geometric and/or material property) features may include data calculated and/or measured prior to measurement of the device to facilitate rapid identification of the device structure. These results (e.g., determined features) may also be used to alert the manufacturer of process variations, feedback, or feed-forward, as previously described.

In various designs, the main pulsed laser beam impinges a spot on the surface of an integrated circuit (e.g., a silicon integrated circuit). The pulses may generate light at the second harmonic of the main beam via interaction with the integrated circuit (e.g., a device in the integrated circuit). The SHG signal is measured using one or more detectors. The measurement may include the intensity, angular distribution, polarization, or any combination thereof of the SHG light. The sample may also be rotated to make multiple measurements (e.g., corresponding to different angles of incidence and/or SHG light emitted in different directions) and the wavelength of the main beam may also be changed.

The detected SHG signal may be processed and compared to a detected SHG signal generated by computer simulation using a model. The model may contain geometric information (such as one or more sizes or shapes) from the sample. In some examples, the geometric information (e.g., reference geometric information) may include at least two dimensions. For example, the geometric information may include the height, width, or length of the features and may potentially include the thickness and/or spacing. Geometric information may also include shapes, for example, shapes may include angles, orientations, smoothness, roughness, or other features or characteristics.

The model may be empirically generated from measurements or calculated, or a combination of both. The model may be used to evaluate the processed SHG optical signal to determine the structure (e.g., geometry) or change in structure (e.g., geometry) of the device on the sample.

The result of the comparison may be used to monitor a manufacturing process. In some examples, if the comparison indicates a significant change in device structure (such as device geometry) (e.g., an unintended change in geometry), the procedure may be temporarily suspended until the problem is resolved. Additionally or alternatively, the results of the comparison may be used to help develop new device structures or programs for the manufacture of a device.

Fig. 20 illustrates an exemplary SHG-CD system 4000 for measuring and monitoring characteristics (e.g., critical dimensions) of a sample or devices included in the sample. In the example shown in fig. 20, a laser source 4100 (e.g., a pulsed laser source such as a Ti: sapphire laser) may be 4100 for generating a laser beam 4110. In some cases, laser beam 4110 may include pulses having a duration of from 10 to 50 femtoseconds, 50 to 100 femtoseconds, from 100 to 150 femtoseconds, 150 to 200 femtoseconds, or any value in between or greater or less than these ranges. In some cases, laser beam 4110 may have a wavelength (e.g., a center wavelength) of any value from 500nm to 700nm, from 700nm to 900nm, from 900nm to 1200nm, from 1200nm to 1500nm, from 1500nm to 2000nm, or between them or more or less. In some cases, laser beam 4110 may include pulses having a duration of 100 femtoseconds and have a wavelength (e.g., a center wavelength) of 800 nm. In some of these cases, the laser source 4100 may be a coherent Mira Ti: sapphire laser. The laser beam 4110 may be directed to a sample 4302 to be detected. In some examples, a polarizer 4120 may select the polarization of the laser beam 4110, and the focusing optics 4130 may focus the laser beam 4110 on the sample 4302 and thereby illuminate a spot or area 4300 on the sample 4302. In some cases, the illuminated spot or area may contain one or more devices (e.g., semiconductor devices) or structures. In some cases, portions of one or more devices may overlap with the illuminated area. In some cases, the sample 4302 may be seated on an object stage 4301, the object stage 4301 may be positioned (e.g., laterally along x and/or y directions in a plane parallel to a top surface of the sample 4302) and/or rotated (e.g., in an azimuth or polar direction relative to a Cartesian coordinate system having an axis perpendicular to the surface of the sample (e.g., the z-axis of the xyz system shown in FIG. 20). The devices on the sample 4302 may be complete or at various stages of production (e.g., at an early stage), such as after fabrication of the gate layer or after lithographic exposure and development of a photoresist or hard mask. In some cases, the object table 4301 may be movable or adjustable such that a portion of the sample 4302 illuminated by the laser beam 4110 is movable (e.g., laterally). In some examples, the height and/or rotational state of the object table 4301 can be adjustable (e.g., manually or electronically). For example, the angle of incidence of the laser beam 4110 relative to the sample 4302 can be controlled by controlling the azimuth angle of the object table 4301.

In certain embodiments, the object table 4301 may not be part of the SHG-CD system 4000. In some cases, the object table 4301 may be included in a tool of a corresponding production line. In some cases, the SHG-CD system 4000 can communicate with a tool to send control signals for controlling the position/orientation of the object table 4301 or to receive read signals indicative of the position/orientation of the object table 4301.

In some implementations, one or more detectors 4201, 4210 may be positioned relative to an illuminated spot or area 4300 in order to collect at least one light beam 4400 emitted or reflected from the illuminated area 4300. In some cases, the light beam 4400 may include a second harmonic of the laser beam 4110 emitted by the sample 4302 (e.g., via a second order nonlinear interaction of the laser beam 4110 with the sample 4302). In some examples, detectors 4201, 4210 may detect second harmonic generated light 4400 (also referred to as SHG signals and/or SHG light) having a wavelength of 400nm generated upon interaction of laser beam 4110 having a wavelength of 800 nm. In some cases, the detectors 4201, 4210 may be positioned or moved to different positions to sample light beams (e.g., SHG light) traveling at different angles (e.g., different tilt angles and/or different azimuth angles). In some examples, the detectors 4201, 4210 may include one or more filters (e.g., filter 4230). In some such examples, spectral filter 4230 may be used to block, filter, or eliminate light having a wavelength other than the second harmonic of beam 4400. In some cases, the detectors 4201, 4210 may include one or more polarizers (e.g., polarizer 4220). In some such cases, the polarizer 4220 may be used to select the polarization of the detected light, e.g., by allowing transmission of light having a first polarization state and absorbing or redirecting light having a second polarization. In some cases, detector 4201 may be a detector module including detector 4210 and one or more optical components. In some cases, detector 4201 or detector 4210 may form a detector array. In some cases, the detectors 4201, 4210 may include a photomultiplier tube (e.g., for measuring the intensity of SHG light). In some cases, the detectors 4201, 4210 may include one or more optical components configured to direct and/or focus the SHG light 4400 to the detector 4210. In some implementations, at least one detector may be used to detect light having the wavelength (also referred to as the dominant wavelength) of laser beam 4110.

In some implementations, the system may compare the measured SHG signal (e.g., the detected SHG signal) to a predicted SHG signal or a predicted detected SHG signal generated by simulating second harmonic generation by a digital model of the measured device (e.g., an electronic device such as a semiconductor device) using the measured device. The result of this comparison may be used to determine the size (or shape) of the physical feature of the measured device, or whether a change in size (or shape) has occurred, e.g., as compared to: a previously measured size (e.g., stored in the memory of the system), a size for simulating the SHG signal, or a reference size (e.g., stored in the memory of the system).

In some implementations, the SHG-CD system may compare a first SHG signal or a first group of SHG signals received from a first sample with a second SHG signal or a second group of SHG signals received from a second sample, for example, to detect a change in a manufacturing process. For example, the SHG-CD system may measure a first detected SHG signal or a first group of detected SHG signals and compare them to a second detected SHG signal or a second group of detected SHG signals stored in the memory of the system. The second detected SHG signal or the second group of detected SHG signals may be received from a second sample and stored after receiving the first SHG signal or the first group of SHG signals from the first sample. In some cases, the first and second samples may be manufactured by the same manufacturing system. In some cases, a difference between the first detected SHG signal and the second detected SHG signal may be indicative of a change in a manufacturing step in the manufacturing process. In some cases, if the difference exceeds a specified value (e.g., a specified value stored in a memory of the SHG-CD system), the SHG-CD system may output a signal indicating a change in the manufacturing step. In some cases, the manufacturing step may be a manufacturing step performed on the first and second samples prior to the SHG measurement.

To generate a digital model of the SHG signal, the geometry and materials of a device structure and optical configuration (for the lighting device) may be input to a modeling program (e.g., a program for modeling nonlinear light-matter interactions) that calculates predicted SHG emissions for the provided device structure and optical configuration. For example, fig. 21 shows a simplified configuration of a FinFET transistor 4500 on a silicon wafer 4540. The FinFET transistor has a silicon fin 4510, a hafnium oxide gate oxide layer 4520 and a tungsten gate contact layer 4530 that are 5nm wide. As shown in fig. 21, such a transistor has geometric features such as dimensions (e.g., height, width, and the like), and/or shapes including slope (or lack thereof) and sidewall slope (or lack thereof). Fig. 22 shows a one-dimensional array 4560 formed from a plurality of FinFET transistors. In some cases, for simulation purposes, the one-dimensional array 4560 may be assumed to be infinitely wide and repeated indefinitely. As shown in fig. 22, the one-dimensional array has geometric features of individual FinFET transistors, such as spacing between FinFET transistors, and dimensions (e.g., height, width, and the like), and/or shapes (e.g., slope (or lack thereof), sidewall slope (or lack thereof), and the like).

Fig. 23 shows an example procedure that may be used to generate a predicted SHG signal and a predicted detected SHG signal. In fig. 22, a device model 4610 (e.g., digital model) of FinFET array 4560 and a beam model 4620 of incident pulsed beam 4110 are used as inputs to software 4630, which software 4630 is capable of modeling SHG light emitted by a structure (e.g., a structure on a sample to be measured) when illuminated by an incident light beam. Examples of such software may include, but are not limited to: lumerical's FDTD (finite difference time Domain) software available from Ansys Canada Ltd, vancoupia, columbia. In some cases, the device model may include geometry and material properties of the structure under test (e.g., finFET array) and the beam model may include beam parameters of the light beam incident on the structure. Modeling software 4630 may calculate an emission pattern from SHG light expected from the incident light beam illumination structure. In some examples, the resulting emission pattern may be input to a detector model 4640 (e.g., a detector model associated with a detector or detector type used to measure emitted SHG light), the detector model 4640 may filter the emission pattern and generate the SHG signal 4650 for the expected detection of the sample geometry and material 4610. In some cases, the detector model may filter the emission pattern based on, for example, an entrance aperture of the detector.

Fig. 24 shows simulated detected SHG signals plotted against the width of a FinFET transistor (e.g., a silicon FinFET), showing an example relationship between simulated detected SHG signals and Fin width. In some cases, the detected SHG signal may be proportional to the intensity of SHG light generated by the FinFET when illuminated. In the example shown, the data points of the SHG signal are calculated for a discrete series of fin widths in the range of 1nm to 10nm in 1nm steps. The results are a graph 4670 of the relative SHG intensities (e.g., normalized intensities) for different fin widths as shown in fig. 24 (filled circles). In some cases, graph 4670 may be used to predict the width of a FinFET under test (e.g., having the same geometry as the FinFET used in the simulation) based on a measured SHG signal from the FinFET under test. For example, a measured SHG signal strength 4680 may be used to determine the width of the silicon fin on the device (in this case 5.5 nm) by interpolating between calculated data points at 5nm and 6 nm. Interpolation, extrapolation, and other methods may be employed.

In some examples, more than one possible change in device geometry may cause similar changes in the SHG signal generated by the device, making it difficult to identify the change that occurred (e.g., relative to a previously measured device, or a reference device). For example, a change in height or a change in width of the device may cause the same change in the SHG signal. Thus, it may be desirable to use additional detectors that measure the emitted light at different angles (e.g., tilt angles) and/or different polarizations using additional data obtained from the signals provided by the additional detectors to more accurately capture the changes. In some examples, additional detectors may be introduced into the detector model 4640 in fig. 23. This provides an additional signal that can be used to compare the predicted and measured detected SHG signal (or SHG signal). In some cases, such additional signals may be used to distinguish between different geometric changes of the device.

There are a number of ways to introduce additional detectors into the system. In one example, an additional detector is added as shown in fig. 25. In fig. 25, detector 4201 is complemented by additional detectors 4202 and 4203 that may be used to measure SHG at additional angles (e.g., different tilt angles) and/or different polarizations of the SHG signal. The detector may also be positioned at different azimuth angles with respect to the sample and the sample holder/sample stage. In some cases, an additional detector may include a polarizer 4220 having different polarization-selective properties than one or more detectors in the SHG-OC system. In some cases, the additional detectors may include filters 4230 having different polarization-selection properties than one or more detectors in the SHG-OC system.

In some examples, the SHG signal may be detected with a detector array (such as a linear or area detector) that may allow light at multiple angles to be captured simultaneously. Fig. 26 illustrates an SHG-CD system including at least one linear or area detector array 4795 for detecting SHG light emitted by a sample 4770 in different directions. In the example shown in fig. 26, post lens (through-the-lens) detection is used. In this configuration, the pulsed beam 4700 passes through optics 4701 and a polarizer 4702 and is then directed by the dichroic beam splitter 4710 through the objective lens 4720 placed over the sample 4770 to illuminate a spot 4760 on the sample 4770 sitting on a stage 4780. The emitted SHG light 4790 is collected by the objective lens 4720 and passes through a dichroic beam splitter, an optical filter (e.g., spectral filter) 4740, and collimating optics 4750 onto a linear or area detector array 4795 (e.g., a 1D or 2D detector array). In some cases, light incident on the objective at different angles will be imaged onto different pixels of the detector array 4795. In some cases, the SHG light collected from different tilt angles may be measured simultaneously.

In some embodiments, additionally or alternatively, SHG light may be used for production monitoring, for example, by monitoring dimensional (e.g., height, width, etc.) or geometric changes (e.g., shape) in devices produced during manufacturing. Fig. 27 illustrates an exemplary procedure for using an SHG-CD system (e.g., the SHG-CD system described above) in a production setting. In various embodiments, the SHG-CD system may be used to monitor samples in real-time as they are produced in a production line. In some of these cases, the SHG-CD system may back-illuminate a sample at a selected stage of production and determine one or more characteristics (e.g., geometric and/or material characteristics) of the sample by measuring the corresponding SHG signal. In the example shown, the SHG signal may be monitored for changes in dimensions indicative of features of the fabricated device (e.g., as compared to a reference dimension). In fig. 27, a model 4801 can be used to create a program window 4802, comparing the program window 4802 to the SHG signal 4803 collected from a sample. In some examples, the signal may be monitored by software 4805 for changes that exceed a program window. In some cases, the program window may include upper and/or lower limits on geometric features or critical dimensions. In some cases, the upper and lower limits may be stored in a memory of the system. When the signal passes the program window, an alert may be sent to the factory computer or line operator 4806 or otherwise directed. As discussed above, such SHG signals may correspond to SHG signals measured separately for different tilt angles, azimuth angles, polarizations, or any combination thereof.

In some implementations, the SHG-CD system may include a non-transitory memory configured to store data and machine-executable instructions and a processor (e.g., hardware processor, processing electronics, a microprocessor, and the like) configured to execute machine-readable instructions to execute one or more programs associated with monitoring samples including one or more devices using the second harmonic generation method described above. In some examples, a reference SHG model and modeling software (e.g., electromagnetic simulation software capable of modeling second harmonic generation) of a device contained in a sample may be stored in non-transitory memory as reference information and instructions, respectively. The processor may execute instructions to calculate one or more expected second harmonic emission patterns associated with the device using at least the reference information as an input. In some cases, the processor may calculate the expected emission pattern using one or more parameters of an incident beam of SHG light used by the SHG-CD system to generate the SHG light. In some examples, parameters of the incident beam may be stored in memory of the SHG-CD system (e.g., as part of the reference information). In some examples, the processor may receive parameters of the incident beam from a control system of the SHG-CD system that controls the incident beam illuminating the sample. In various examples, the reference information may include values for determining a reference model, generating one or more parameters of a lookup table, reference values associated with a program window, parameter values associated with a detector, and the like.

In addition to or in lieu of calculating the reference SHG model using a nonlinear electromagnetic modeling software 4630 or other theoretical modeling method, the characteristics of the second harmonic light (SHG light) generated and emitted from a device may be determined experimentally and used to construct a reference SHG model.

In some examples, the reference SHG model may be empirically generated by measuring SHG signals from a reference sample having known dimensions and/or material properties and creating a plot similar to chart 4670 or another reference database (e.g., a look-up table or LUT), which may then be used to determine characteristics (e.g., dimensions and/or material properties) of a new sample having unknown characteristics (e.g., a device in the new sample) using measured second harmonic light generated by the new sample.

In some cases, a SHG signal generated by a sample (e.g., an integrated circuit) may be used to determine a geometric feature of a sample based at least in part on a mapping of the SHG signal to geometric features of the sample or one or more portions of the sample (e.g., a lookup table of SHG signal values and geometric features). In various embodiments, the sample may or may not have been completed. In some cases, the image may be generated using empirical data, simulated data, or a combination thereof. In some cases, the map may be generated using a machine learning algorithm. In some cases, the mapping of SHG signals to geometric features of the sample may include a mapping of detected SHG signals to geometric features of the sample or one or more portions of the sample (e.g., a lookup table of detected SHG signal values and geometric features). In some cases, the mapping may include a mapping of the detected SHG signals to geometric features of one or more structures (e.g., the one or more structures may or may not have been completed) on the sample at a stage during a manufacturing process.

In some cases, a change in an SHG signal generated by a sample (e.g., an integrated circuit) due to a change in a parameter (e.g., polarization, incident angle, intensity, and/or wavelength) of an incident light beam that generates the SHG signal may be used to determine a geometric feature of the sample. In such cases, the geometric feature may be determined based on a mapping of the change in the SHG signal to the geometric feature of the sample or one or more portions of the sample (e.g., a look-up table of change in SHG signal values and geometric feature). In various embodiments, the sample may or may not have been completed. In some cases, the image may be generated using empirical data, simulated data, or a combination thereof. In some cases, the map may be generated using a machine learning algorithm. In some cases, the mapping of the change in the SHG signal to the geometric feature of the sample may include a mapping of the change in the detected SHG signal to the geometric feature of the sample or one or more portions of the sample (e.g., a lookup table of detected changes in SHG signal values and geometric features).

In some examples, a reference SHG model may be generated using a machine learning algorithm including a supervised learning algorithm, an unsupervised learning algorithm, a semi-supervised learning algorithm, or reinforcement learning. In such examples, the machine learning techniques may use physical metrology and/or computer modeling, or a combination thereof, to generate the reference SHG model. In some cases, the reference SHG model may include a mapping of SHG signals and/or detected SHG signals to characteristics of the sample (e.g., geometric features, material structures, critical dimensions, and the like). In various embodiments, the machine learning algorithm for generating the map may include: linear regression, logistic regression, decision trees, support Vector Machine (SVM) algorithms, naive Bayes algorithms, K-nearest neighbor (KNN) algorithms, K-means algorithms, random forest algorithms, dimension reduction algorithms, gradient lifting algorithms, or adaboost algorithms.

In some examples, a processor or a separate computing system of the SHG-CD system may be used to generate the reference SHG model using machine learning techniques and a series of specified measurements performed on multiple reference devices with known characteristics. In some cases, a processor of the SHG-CD system or a separate computing system may use an unsupervised machine learning technique to generate the reference SHG model, as the system is used to monitor samples produced on the production line on-line.

In some examples, the angular distribution of SHG emissions from the samples may be used to refine the size measurement. For example, separate SHG signals collected from at least two angles (tilt and/or azimuth) may be used.

In some examples, the polarization of a source or a polarizer used in an optical path between a detector or sample and the detector may be changed to produce incident beams having different polarizations or to selectively detect SHG light having a particular polarization. In some cases, separate SHG signals collected for at least two polarizations may be used to refine the dimension measurement.

In some examples, separate SHG signals may be collected for at least two different incident light beams having different wavelengths. For example, at least two separate light sources (e.g., lasers) having separate center wavelengths may be directed onto the sample, resulting in different SHG signals having different wavelengths collected by different detectors (e.g., detectors having different filters or different filters in the optical path from sample to detector). In some cases, separate SHG signals may be used in the analysis of the device under test (e.g., to refine dimensional metrology). Other configurations are possible. For example, a broadband light source may be used to generate a broadband incident light and several detectors, detector arrays, or spectrometers may be used to detect and analyze the resulting SHG light. In some cases, the light source may comprise a tunable wavelength laser light source. In some cases, a single light source may be used to simultaneously produce two light beams having two different wavelengths, or to produce light beams having different wavelengths at different times.

In some examples, the SHG-CD system may use at least two detected SHG signals that differ in at least one parameter to determine a geometric feature of the sample or a change in the geometric feature of the sample. The at least one parameter may be associated with generation and/or detection of a corresponding SHG signal of a person that generated the detected SHG signal, respectively, upon detection. In some cases, the at least one parameter may include a parameter associated with an incident light beam that produces the SHG signal. For example, the incident light beams may have different wavelengths, azimuth angles, polarizations (e.g., linear or circular polarizations), intensities, angles of incidence (e.g., relative to the sample), and the like. In some cases, the incident light beams may have different polarization parameters. In some cases, the at least one parameter may include a parameter associated with the detected SHG signal. For example, the SHG signal may propagate in different directions (e.g., relative to the sample), have different polarizations or different wavelengths, and the like. Thus, in some cases, the at least one parameter may include a parameter associated with a beam of light from the sample to the detector. In various implementations, polarizers, filters, or other optical components may be included in the optical path between the sample and the detector, e.g., to select a polarization, wavelength, angle, etc. In some cases, the at least one parameter may include a parameter associated with a detector used to detect the SHG signal and generate the detected SHG signal. For example, the detectors may have different tilt angles (e.g., relative to the sample), different polarizers, different filters, different azimuth angles, different out-of-plane angles relative to the sample, different in-plane angles, and the like. In some cases, an in-plane angle may include an angle in a plane formed by the incident light beam and an axis perpendicular to the sample. In some cases, an out-of-plane angle may include an angle in a plane that is different from (e.g., not parallel to) the plane formed by the incident light beam and the axis perpendicular to the sample. In some implementations, the SHG-CD system may change the beam of the incident beam and/or the SHG signal and/or parameters of the detector (e.g., polarization, wavelength, angle, etc.) over time to obtain different SHG signals and/or detected SHG signals for different parameters.

In some implementations, the SHG-CD system may use at least one light source and one detector to generate at least two detected SHG signals that differ in at least one parameter to determine the geometric feature of the sample or a change in the geometric feature of the sample. The at least one parameter may be associated with generation and/or detection of a corresponding SHG signal that, when detected, respectively results in the detected one of the SHG signals. In some cases, at least two detected SHG signals may be generated at different times. In some such cases, at least one parameter may have a first value at a first time and a second value at a second time subsequent to the first time, resulting in the generation of two different detected SHG signals. In some cases, the at least one parameter may include a parameter associated with the individual incident light beams that produced the SHG signal. For example, the parameters may include wavelength, azimuth angle, polarization (e.g., linear or circular polarization), intensity, angle of incidence (e.g., relative to the sample), and the like. In some cases, the parameters may include polarization parameters of polarized light (e.g., linearly or circularly polarized light). In some cases, the at least one parameter may include a parameter associated with the detected SHG signal. For example, the parameters may include propagation direction of the SHG signal direction (e.g., relative to the sample), polarization, wavelength, and the like. In some cases, the at least one parameter may include a parameter associated with a detector for detecting the SHG signal and generating the detected SHG signal. For example, the parameters may include the position of the detector, tilt angle (e.g., relative to the sample), detection wavelength of a detector, passband of a filter, azimuth angle, out-of-plane angle relative to the sample, different in-plane angles relative to the sample, and the like. In some cases, the in-plane angle with respect to the sample may include an angle in a plane formed by the incident light beam and an axis perpendicular to the sample. In some cases, the out-of-plane angle with respect to the sample may include an angle in a plane that is different (e.g., not parallel) to the plane formed by the incident light beam and an axis perpendicular to the sample.

In some examples, the results of SHG sizing measurements are used for program monitoring. For example, the SHG-CD system (or the monitoring method described above) may be used to estimate characteristics of samples produced by a process at a production stage. In some of these examples, the SHG-CD system may be used for online and real-time program monitoring (e.g., the SHG-CD system may be included as an online metrology tool in an online of a manufacturing system (e.g., a semiconductor manufacturing system)). In some examples, the SHG-CD system (or the monitoring method described above) may be used to monitor selected (e.g., randomly selected) samples offline. Thus, in various embodiments, the SHG-CD sizing system includes a production or program monitor for dimensional or geometric changes of the device during manufacturing.

In another example, the results of the SHG dimension measurement may be used as program feedback or feed forward to correct the program as needed, as shown in fig. 28 and 29, respectively. In some example processes such as those shown in fig. 28, the SHG-CD system (or the sample monitoring method described herein) may be used to perform a change in a characteristic (e.g., a dimensional characteristic) of a post-determined sample of a process at a selected stage of a production line and one or more feedback signals may be generated based at least in part on the determined characteristic to adjust one or more parameters of the process. In some cases, one or more feedback signals may be used to modify the process such that after the feedback signal is applied, the characteristics of the samples produced by the selected stage are closer to a reference characteristic (e.g., the characteristics of a reference device) than the samples produced prior to the application of the feedback signal.

In some example processes such as those shown in fig. 29, the SHG-CD system or monitoring method described herein may be used to perform a change in characteristics of pre-determined samples of a process at selected stages of a production line and generate one or more feed-forward signals to adjust one or more parameters of the process based at least in part on the determined characteristics. In some cases, one or more feedforward signals may be used to modify the process such that, after the feedforward signal is applied, the determined characteristics of the samples produced by the selected stage are closer to a reference characteristic (e.g., the characteristics of a reference device) than the samples produced prior to the application of the feedforward signal. In some cases, a feed forward signal may be used in an adjustment procedure to correct for the determined variation in the characteristic.

In some examples, the SHG-CD system may determine an unplanned variation in a geometric characteristic of a sample by measuring the sample (using the SHG signal) and generate a feedback signal (or feed-forward signal) configured to adjust a processing tool in a production line to reduce or eliminate the unplanned variation in subsequently produced samples (or correct for an unplanned variation detected in the measured sample). In some cases, the SHG-CD system may generate a signal or data indicating whether an unplanned change is identified and transmit the signal or data to a user interface of the SHG-CD (where a user may observe and evaluate the detected unplanned change) or a computing system in communication with the SHG-CD.

In some example embodiments, the results of SHG dimension measurements may be used in conjunction with results obtained from one or more other systems, such as other test and/or metrology systems (e.g., optical critical dimension systems also known as OCD systems), to determine a geometric feature or variation of a geometric feature. The results from the SHG-CD system and the OCD system may be received, for example, by one or more processors that determine geometric features or changes thereof based on inputs from the SHG system and the OCD system. One or more other systems may also be used instead of or in addition to the OCD system.

In some implementations, one or more processors and/or processing electronics, such as described herein, are used to determine the geometry or change in geometry of one or more devices or portions of one or more devices that have been completed or partially completed based on one or more SHG signals.

In various embodiments, an optical metrology system, such as an SHG-CD system (e.g., SHG-CD system 4000, 6000, or 8000) may be controlled by a control system. In some cases, the control system may be configured to control parameters (e.g., angle of incidence, polarization, wavelength, intensity, divergence, etc.) of the light beam incident on the sample. In some cases, the control system may be configured to control parameters of the detector module of the SHG-CD system (e.g., detecting photodetector gain, detecting polarization and/or wavelength of light received by the photodetector, etc.). In some cases, the control system may be part of an SHG-CD system. In some cases, the control system may include a non-transitory memory and at least one processor or processing electronics. In some cases, the SHG-CD system may include a computing system configured to perform calculations and simulations using at least one SHG signal generated by the detector to generate characteristics of a device monitored by the SHG-CD system. In some cases, the computing system may be in communication with a control system, a detector, and/or a light source. In some cases, a computing system may include a non-transitory memory configured to store data and machine-executable instructions and a processor configured to execute machine-readable instructions to perform one or more processes related to sample monitoring using at least one SHG signal.

In some cases, the control system may include a programmable controller (e.g., a field programmable gate array). In some cases, the computing system and/or control system may be separate from the SHG-CD system, but communicate with the interface of the SHG-CD system through a wired or wireless link. In some cases, the computing system may include a control system. For example, the instructions stored in the memory of the computing system may include instructions for controlling the SHG-CD system and instructions associated with electromagnetic simulation software.

In some cases, the control system may control one or more parameters related to the detected SHG signal. For example, the control system may change a parameter of the light source that generated the incident light beam, a parameter of the light beam after being emitted by the light source and before being incident on the sample, a parameter of the SHG signal generated by the sample, or a parameter of a detector that detects the SHG signal and generates the detected SHG signal.

In some embodiments, SHG-CD may be used to monitor a fabrication process without determining characteristics (e.g., geometric characteristics, material properties, or critical dimensions) of a sample (or a partially or fully formed device contained in the sample) fabricated by the fabrication process. For example, an SHG-CD system may compare one or more detected SHG signals received from a first sample produced by a manufacturing step in a manufacturing process with one or more SHG signals received from a second sample produced by the same manufacturing step after processing the first sample to detect a change in the manufacturing step. In this example, a difference between the SHG signals received from the first and second samples (and thus the detected SHG signals) may indicate a change in a post-fabrication step in which the fabrication step is performed on the first sample. In some cases, a difference between the modified or processed detected SHG signals received from the first and second samples may indicate a change in a post-fabrication step in which the fabrication step is performed on the first sample. Similarly, the SHG signal of a sample may be compared to one or more references (e.g., a reference database, one or more reference values, or one or more reference signals) without determining characteristics (e.g., geometric characteristics, material properties, or critical dimensions) of the sample (or a partially or fully formed device contained in the sample) fabricated by the fabrication process. Thus, in some cases, a modified or processed detected SHG signal may be generated by a processing system of the SHG-CD without having to determine (e.g., quantify) geometric characteristics (e.g., size, shape, etc.) of features of a sample that control the intensity of the SHG signal from the detected SHG signal. In some cases, the first and second samples may be measured using a plurality of incident beams and based on a plurality of SHG signals generated by the incident beams. In such cases, a change in the differently detected SHG signal or a relative change between the two detected SHG signals may be indicative of a change in the manufacturing steps. In some implementations, a comparison of the detected SHG signal (modified or unmodified) from the first sample with the detected SHG signal (modified or unmodified) from the second sample may be made. In some implementations, the detected SHG signal (modified or unmodified) from one or more samples may be compared to one or more references (e.g., a reference database, one or more reference values, or one or more reference signals).

Thus, in some cases, the SHG-CD system may use changes in one or more detected SHG signals (or modified SHG signals) received from a manufactured sample to detect changes in the corresponding manufacturing process without determining characteristics (e.g., geometric characteristics, a material property, or a critical dimension) of the sample. In some of these cases, the SHG-CD may generate a feedback signal to modify a previous manufacturing step of the manufacturing process performed on the sample before detecting the change, or generate a feed-forward signal to modify a next manufacturing step to be performed on the sample after detecting the change.

Likewise, in some embodiments, an SHG-CD system may compare one or more detected SHG signals received from a sample generated by a fabrication process to a reference (e.g., a value or range of values from a lookup table) to detect changes in the fabrication steps of the fabrication process without determining characteristics (e.g., geometric characteristics, a material property, or a critical dimension) of the sample.

Additional examples:

disclosed herein are other examples and implementations of systems and methods.

In some cases, the SHG-CD (or the sample monitoring methods described herein) may be used to monitor dimensional characteristics of an integrated circuit, a portion of an integrated circuit, or a class of devices fabricated on the integrated circuit.

In various implementations, the size/geometry features may include size/geometry features of finfets, GAAs, tri-gates, and other electronic or photonic devices.

In some cases, the size/geometry features may include the size/geometry features of a building block (e.g., NAND gate) of a device of the digital circuit.

In some embodiments, the SHG-CD may include a post-lens imaging system, an optical system based on the use of a Solid Immersion Lens (SIL), or an angle-resolved imaging system. In some cases, SHG-CD systems may use a Solid Immersion Lens (SIL) to provide higher magnification, higher spatial resolution, and/or higher numerical aperture than conventional lenses by filling the object space between the sample and the objective lens. In some cases, the SIL may be located below the front lens of the microscope objective. In some cases, the SIL may include a flat bottom hemisphere, a flat bottom hyper-sphere (Weierstrass), a hemisphere with a tapered tip, a hyper-sphere with a tapered tip, a hemispherical SIL with a tapered dielectric probe, or a diffraction-based SIL. In some examples, the SHG-CD system may use a through-the-lens imaging system to measure the intensity of a beam (e.g., SHG signal) received from a sample through the same lens used to image the sample. In some examples, the SHG-CD system may use an angular resolved imaging system to capture an image of a sample including a number of pixels in which a detection photodetector array (e.g., 1D or 2D) is used, where each pixel in the captured image corresponds to a unique emission direction from the sample. In some cases, the image may be converted to a polar coordinate system to show the angular distribution of light emitted or reflected by the sample.

In various implementations, the SHG-CD system may be configured to collect SHG light emitted by a sample at different scattering angles, in-plane (e.g., a plane formed by the incident beam and the reflection of the incident beam off the sample surface), and out-of-plane detection angles.

In some cases, the SHG-CD system may change the incident angle of the incident beam, for example, to measure the size/geometry of a device. In some cases, the SHG-CD system may rotate the monitored sample, for example, to measure the size/geometry of one or more devices on the sample.

In some cases, the light beam incident on the sample may be changed. For example, multiple wavelengths may be provided in series (e.g., different wavelengths at different times). In some implementations, multiple wavelengths may also be provided together (e.g., simultaneously). In some designs, the light source comprises a broadband light source. In these different configurations, the wavelength of the light is changed to produce different SHG signals for different wavelengths incident on the sample.

In some cases, a sample may be charged (pre-charged) prior to measuring the SHG signal. Such charging may be provided, for example, by a corona gun. Light may also be used to induce charging. In some configurations, such as those described above, a pump and probe arrangement is used in which the pump and probe source are used to provide charge along with a SHG beam to interrogate the sample.

In various implementations, the SHG system analyzes the SHG signal (e.g., data obtained from the SHG signal) and provides feedback (or feedforward) based on this analysis. As discussed herein, the SHG signal or data obtained therefrom may be compared to a look-up table. The SHG systems and methods described herein may include model-based methodologies. For example, the SHG signal (modified or unmodified) may be compared to reference data provided by a model, e.g., the model may be used with simulation software to generate reference data that is compared to the detected SHG signal (modified or unmodified). Furthermore, as discussed herein, artificial intelligence may be used in connection with analyzing data obtained from the SHG.

In some cases, SHG-CD systems may use SHG light to detect electrical defects in a sample. In some cases, the SHG-CD system may use SHG light to detect strain changes in the sample. In some implementations, the SHG system may combine the detected dimensional changes with the detected strain changes or electrical defects (for example) to evaluate a procedure used in the production of the sample.

In certain embodiments, the SHG-CD system is used in conjunction with other metrology instruments (such as other optical metrology instruments, such as optical scatterometry, also known as OCD). In some example embodiments, the results of SHG dimension measurements are used in conjunction with the results of one or more other systems (such as other test and/or metrology systems, e.g., such as OCD) to determine a geometric feature or variation of a geometric feature. The results from the SHG system and the results of an OCD system may be received, for example, by one or more processors that determine a geometric feature or change thereof based on inputs from the SHG system and the OCD system. One or more other systems may also be used instead of or in addition to the OCD system. In some configurations, the optical scatterometry system may be included with the SHG-CD system in a single tool that may perform both measurements. In some implementations, a reference model that incorporates both OCD measurements and SHG-CD measurements may be used. For example, as described above, signals from these instruments (e.g., OCDs and SHG-CDs) may be compared to references from reference models to determine geometric features, such as dimensions, shapes, or changes in geometric features.

In some cases, the SHG-CD system or a separate system can control the amount of charge on the surface of the sample being monitored (e.g., using a corona gun or capacitive coupling). In some cases, the amount of charge on the surface of the sample being monitored may be controlled to enhance or alter the SHG signal. In these cases, the SHG-CD system (e.g., a controller or processor of the SHG-CD system) may use an electronic sensor and change the amount of charge on the sample by controlling the corona discharge (e.g., using a corona gun) applied to the sample and determine the characteristics of one or more SHG signals of different amounts of charge. In various embodiments, the amount of charge deposited on the sample may be determined by measuring the current caused by the charge deposited on the sample surface using an ammeter (e.g., an electrometer or ammeter) located between the sample and the electrical sensor.

In some cases, the sample (e.g., the monitored surface of the sample) may be charged (precharged) prior to measuring the SHG signal.

In some cases, the SHG-CD system may illuminate areas of the sample illuminated by the first and second (e.g., beam) light or light sources. In some cases, a first (e.g., beam) light may be used to generate SHG light and a second (e.g., beam) light may control or detect the generation of SHG light.

Various methods and configurations for characterizing a sample by controlling the charge density on the sample or using additional light (pump-detection techniques) are described above. In these configurations, the SHG-CD may include at least one light source for generating the detection radiation and at least one light source for generating the pump radiation.

In some cases, the SHG-CD system may use SHG light to detect electrical defects in the sample. In some cases, the SHG-CD system may use SHG light to detect strain changes in the sample. In some embodiments, the SHG system may combine the detected dimensional changes with the detected strain changes or electrical defects to evaluate a process used in the sample production process, generate feedback signals for adjusting one or more parameters of the process, and/or generate feedforward signals for adjusting subsequent process parameters.

In various embodiments, an SHG-CD system (e.g., SHG-CD system 4000, 6000, or 8000) may include using one or more of the methods, configurations, or tools described above with respect to fig. 1-19.

In some embodiments, an SHG-CD system (e.g., SHG-CD system 4000, 6000, or 8000) may include a plurality of light sources that respectively generate light beams having different wavelengths. The system may illuminate the device with a plurality of beams and the device may generate one or more SHG signals. The generated beam may be received by one or more detectors, and the detection signals generated by these detectors may be used to determine the critical dimensions of the device. In some cases, different filters may be used along the optical paths to different detectors such that the respective detectors produce detection signals related to the respective wavelengths passing through the respective filters. Alternatively, the generated beam or beams may be directed to a spectrometer that measures the intensity of the generated SHG signal (SHG light) with different frequencies. In some cases, SHG spectral measurements or signals generated by an optical spectrometer can be used to determine the critical dimensions of the device.

In some embodiments, in addition to or in lieu of a detector, an SHG-CD system (e.g., SHG-CD system 4000, 6000, or 8000) may also include at least one spectrometer configured to receive SHG signals from a sample having different frequencies and to measure intensities or ratios between intensities of the different SHG signals. In some cases, the spectral characteristics of the SHG signal may be used to determine characteristics (e.g., geometric features, material structure, critical dimensions) of the sample.

In some embodiments, the SHG-CD may be in communication (e.g., wired or wireless communication) with an optical scatterometry system (e.g., OCD system). In some cases, a processor of a computing system (e.g., a computing system of an SHG-CD or OCD system, or a separate computing system) may receive measurement data or evaluation data (e.g., detected dimensions, materials, defects, flow evaluation data, etc.) from the SHG-CD and OCD systems. In these cases, the computing system may combine the measurement or evaluation data received from the SHG-CD and OCD systems to generate an evaluation report, or to generate feedback and/or feedforward signals for controlling the flow in the respective production lines. In some cases, the SHG-CD system and the OCD system may be combined into a single tool. In these cases, the SHG-CD system and the OCD system may be integrated in the same housing and potentially share one or more optical or electronic components for monitoring the sample. In some cases, a single control system may control both the SHG-CD system and the OCD system. In some cases, the SHG reference model (e.g., empirical reference model) used by the SHG-CD system may be created using measurements obtained from the OCD and SHG-CD systems, and may also contain OCD and SHG-CD measurements.

Fig. 30A is a block diagram of an example SHG-CD system 4950, which includes an optical system 4952, a control system 4954, and a computing system 4956. In some examples, optical system 4952 may include one or more light sources configured to generate one or more primary light beams incident on the sample; one or more detectors configured to receive one or more secondary light beams reflected, scattered, or generated by the sample; and one or more optical, mechanical, and optomechanical components configured to manipulate (e.g., control polarization, filter, redirect, control divergence, etc.) the primary and secondary beams. In some examples, the optical system 4952 may include at least one mechanical stage configured to control the position and orientation of the sample relative to the light source and the detector. In some cases, control system 4954 may be configured to control optical system 4952 according to instructions and/or data stored in a memory of control system 4952, instructions and/or data received from computing system 4956 or user interface 4957. In some cases, the computing system 4956 may be configured to simulate the second harmonic generated by the sample by utilizing one or more models (e.g., reference models, device models, etc.) and data received from the control system 4954 (e.g., data related to the incident light beam). In some examples, the computing system 4956 may be configured to determine changes in the SHG signal, characteristics of the sample (e.g., geometric parameters and/or material characteristics), or changes in sample characteristics using analog data (e.g., data related to analog SHG light emissions) and data received from the optical system 4952 (e.g., measurement data related to SHG light received from the sample). In some examples, the model may be stored in memory of the computing system 4956 or received from the user interface 4957. In some cases, the user interface may include an input interface (e.g., keyboard, mouse, touch screen, touch pad, etc.) for receiving data and instructions from the user, and an output interface (e.g., display) for presenting measurement data, assessment results, images, charts, data/instructions stored in the computing system 4956 and/or control system 4954 to the user.

Fig. 30B is a block diagram of another example SHG-CD system 4960, which includes an optical system 4952 and an interface 4952 in communication with the optical system 4952. In some cases, interface 4962 may be configured to receive instructions and data from control and computing system 4964 separate from SHG-CD system 4960 and to generate one or more control signals based on the received data and instructions. The interface 4962 may be further configured to transmit data received from the optical system 4952 (e.g., measurement data and/or data related to the configuration of the optical system 4952) to the control and computing system 4964. Control and computing system 4964 may include a user interface 4966. In some cases, the user interface 4966 may include an input interface (e.g., keyboard, mouse, touch screen, touch pad, etc.) for receiving data and instructions from a user, and an output interface for presenting measurement data, assessment results, images, charts, data/instructions (e.g., display screen) stored or received in the control and computing system 4964 to a user. In some cases, control and computing system 4964 may include a desktop computer, a notebook computer, or other electronic device.

In some cases, computing system 4954 and control and computing system 4964 may include at least one hardware processor and at least one non-transitory memory in communication with the hardware processor. In some embodiments, the hardware processor may execute computer-executable instructions stored in the non-transitory memory to: calculating an expected SHG signal, an expected SHG light emission pattern, or an expected signal generated by a detector of the optical system 4952, generating a control signal (e.g., a beam of light for controlling the light source, detector, and/or optical system 4952), comparing the expected SHG emission to a measured SHG emission, determining geometric and material properties of the sample (or device in the sample), generating graphical data related to the measured or expected SHG emission, or any combination of such data, or performing other tasks.

In some cases, the optical metrology system can include a corona discharge source (e.g., a corona gun) that can provide different amounts of charge to the sample, and an electrical sensor configured to measure the amount of charge provided to the sample. The optical metrology system may use an electrical sensor and a discharge source to measure and control the amount of charge on the sample (e.g., using a hardware processor or control system). In these cases, the system may use the electrical sensor and the discharge source to provide a variable amount of charge to the sample and determine a change in the detected SHG signal, a geometric feature of the sample, or a change in the geometric feature of the sample based on the determined characteristics of the detected SHG signal for different amounts of charge.

It should be appreciated that optical metrology systems (e.g., systems for measuring, monitoring, and characterizing critical dimensions of a sample) based on SHG effects monitoring a sample (e.g., in a production line) are not limited to those described above (e.g., they may include fewer components, different configurations, additional features, and/or components, alternative features, and/or components).

Examples

Group 1

Some additional non-limiting examples of the embodiments discussed above are provided below. These examples should not be construed as limiting the scope of the invention in any way.

Example 1: a system for characterizing a sample using second harmonic generation, the system comprising:

a sample support configured to support a sample;

at least one light source configured to direct a beam of light onto the sample to generate a plurality of Second Harmonic Generation (SHG) signals;

an optical detection system comprising at least one optical detector configured to receive the SHG signals emitted from the sample and to generate a detected SHG signal;

one or more hardware processors in communication with the optical detection system, the one or more hardware processors configured to:

receiving at least one detected SHG signal; and

Determining a geometric feature of the sample or a variation of the geometric feature of the sample based on the at least one detected SHG signal.

Example 2: the system of example 1, wherein the geometric feature of the sample is determined based at least in part on an image of the plurality of detected SHG signals and geometric features of one or more structures on the sample that are or are not completed.

Example 3: the system of example 1, wherein the one or more hardware processors receive the at least one detected SHG signal after performing the first manufacturing step on the sample.

Example 4: the system of example 3, wherein the system is included in-line in a manufacturing system.

Example 5: the system of example 4, wherein the first manufacturing step is a step in a manufacturing process performed by the manufacturing system.

Example 6: the system of any of the above examples, wherein the one or more hardware processors are configured to:

identifying an unintended variation of the geometric feature of the sample; and

An indication of the unplanned variation is output.

Example 7: the system of example 6, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool in the manufacturing system to adjust for the unplanned variation in the sample.

Example 8: the system of example 7, wherein the one or more hardware processors are configured to output the indication of the unplanned variation to a sample processing tool for performing a second manufacturing step on the sample after the first manufacturing step to adjust the unplanned variation in the sample.

Example 9: the system of example 6, wherein the one or more hardware processors are configured to output the indication of the unplanned variation to a user via a user interface of the system.

Example 10: the system of any of the above examples, wherein the geometric feature comprises a size of one or more devices or one or more portions of devices that have been completed or have not been completed.

Example 11: the system of any of the above examples, wherein the geometric feature comprises a critical dimension of one or more devices or portions of one or more devices that have completed or have not completed.

Example 12: the system of any of the above examples, wherein the geometric feature comprises a shape of one or more devices or portions of one or more devices that have completed or have not completed.

Example 13: the system of any of the above examples, wherein the geometric feature comprises a lateral dimension including a width or a length of one or more devices or portions of one or more devices that have been completed or have not been completed.

Example 14: the system of any of the above examples, wherein the geometric feature comprises a height of one or more devices or portions of one or more devices that have completed or have not completed.

Example 15: the system of any of the above examples, wherein the geometric feature comprises a lateral spacing between devices or portions of devices that have been completed or have not been completed.

Example 16: the system of any of the above examples, wherein the geometric feature comprises an inclination or slope of one or more devices or portions of one or more devices that have completed or have not completed.

Example 17: the system of any of the above examples, wherein the geometric feature comprises a sidewall slope or slope of one or more devices or portions of one or more devices that have completed or have not completed.

Example 18: the system of any of the above examples, wherein the at least one detected SHG signal comprises the plurality of first and second detected SHG signals measured with at least one measurement parameter that is different for the first and second detected SHG signals, and the one or more hardware processors are configured to:

receiving the plurality of first and second detected SHG signals; and

Determining the geometric feature of the sample or a variation in geometric feature of the sample based on the first detected SHG signal and the second detected SHG signal.

Example 19: the system of example 18, wherein the at least one measurement parameter comprises at least one of a measurement location, a measurement angle, a polarization, or a wavelength.

Example 20: the system of any of examples 18-19, wherein the at least one measurement parameter comprises a tilt angle of the measured SHG signal relative to the sample.

Example 21: the system of any of examples 18-20, wherein the at least one measurement parameter comprises an inclination of the at least one detector relative to the sample.

Example 22: the system of any one of examples 18-21, wherein the at least one measurement parameter comprises an azimuth angle of the measured SHG signal relative to an axis perpendicular to a surface of the sample.

Example 23: the system of any of examples 18-22, wherein the at least one measurement parameter comprises an azimuth angle of the at least one detector relative to an axis perpendicular to a surface of the sample.

Example 24: the system of any one of examples 18-23, wherein the at least one measurement parameter comprises polarization of the plurality of SHG signals received by the at least one optical detector.

Example 25: the system of any of examples 18-24, wherein the at least one measurement parameter comprises a polarization of a polarizer of the at least one detector.

Example 26: the system of any of examples 18-25, wherein the at least one measurement parameter comprises a polarization of the light beam incident on the sample.

Example 27: the system of any of examples 18-26, wherein the at least one measurement parameter comprises an inclination angle of the at least one light beam directed at the sample relative to the sample.

Example 28: the system of any of examples 18-27, wherein the at least one measurement parameter comprises an azimuth angle of the at least one light beam directed on the sample relative to an axis perpendicular to a surface of the sample.

Example 29: the system of any of examples 18-28, wherein the at least one measurement parameter comprises a wavelength of the at least one light beam directed onto the sample.

Example 30: the system of any of examples 18-29, wherein the at least one measurement parameter comprises an output wavelength of the at least one light source.

Example 31: the system of any of examples 18-30, wherein the at least one measurement parameter comprises a detection wavelength of the at least one detector.

Example 32: the system of any of examples 18-31, wherein the at least one measurement parameter comprises a wavelength of an SHG signal received by the at least one optical detector.

Example 33: the system of any of examples 18-32, wherein the sample is configured to rotate relative to the light beam and/or the at least one detector.

Example 34: the system of any of examples 18-33, wherein the at least one measurement parameter comprises an angle of the at least one detector that receives the SHG signal propagating in a plane formed by the light beam and an axis perpendicular to the sample.

Example 35: the system of any of examples 18-34, wherein the at least one parameter comprises an angle of the at least one detector that receives an SHG signal propagating out of a plane formed by the light beam and an axis perpendicular to the sample.

Example 36: the system of any of examples 18-35, wherein the at least one parameter comprises a polarization parameter of a linearly or circularly polarized light beam of the at least one light source.

Example 37: the system of any of examples 18 to 36, wherein the at least one light source comprises a broadband light source.

Example 38: the system of any of examples 18-37, wherein the at least one light source comprises at least two different wavelength light sources.

Example 39: the system of any of examples 18-38, wherein the system is configured to change the at least one metrology parameter.

Example 40: the system of example 39, wherein to change the at least one metrology parameter, the one or more hardware processors are configured to cause the at least one light source to simultaneously emit a plurality of wavelengths.

Example 41: the system of example 39, wherein to change the at least one metrology parameter, the one or more hardware processors are configured to cause the at least one light source to emit different wavelengths at different times.

Example 42: the system of any of examples 18-43, wherein the at least one parameter includes an angle of the at least one detected SHG signal and a polarization of the detected SHG signal.

Example 43: the system of any of the above examples, wherein the geometric feature comprises a geometric feature of a completed or not completed integrated circuit device or one or more portions of an integrated circuit device.

Example 44: the system of any of the above examples, wherein the system is included in-line in a semiconductor device manufacturing system.

Example 45: a system as in any of the above examples, wherein the geometric feature comprises a geometric feature of one or more integrated circuit devices or one or more partially completed integrated circuit devices or one or more portions thereof.

Example 46: the system of any of the above examples, wherein the geometric feature comprises a geometric feature of one or more finfets, GAA, tri-gate, or NAND structures.

Example 47: the system of any of the above examples, wherein the geometric feature comprises a geometric feature of one or more three-dimensional structures of the sample.

Example 48: the system of any of the above examples, wherein the at least one light source comprises a first light source configured to emit detection radiation and a second light source configured to emit pump radiation.

Example 49: the system of any of the above examples, further comprising a corona gun configured to deposit different amounts of charge to a top side of the sample.

Example 50: the system of example 49, wherein the one or more hardware processors are configured to determine characteristics of the at least one detected SHG signal, the first detected SHG signal, or the second detected SHG signal for different amounts of charge.

Example 51: the system of any of the above examples, wherein the sample comprises a semiconductor.

Example 52: the system of any of the above examples, wherein the at least one light source comprises a first light source configured to emit a first light beam of a first wavelength and a second light source configured to emit a second light beam of a second wavelength.

Example 53: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive SHG signals at a first angle and a second detector configured to receive SHG signals at a second angle.

Example 54: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive the SHG signal of a first polarization and a second detector configured to receive the SHG signal of a second polarization.

Example 55: the system of any of the above examples, wherein the at least one detector comprises a detector array comprising a number of pixels.

Example 56: the system of any of the above examples, wherein the at least one detector comprises a 1D detector array.

Example 57: the system of any of the above examples, wherein the at least one detector comprises a 2D detector array.

Example 58: the system of any one of examples 55-57, further comprising at least one lens configured to direct SHG signals emitted from a sample at different angles to different locations on the detector array.

Example 59: the system of any of the above examples, wherein the image is generated based on empirical data.

Example 60: the system of any of the above examples, wherein the map is generated via a machine learning algorithm.

Example 61: the system of any of the above examples, wherein the map comprises a look-up table of SHG signal values and geometric features.

Example 62: the system of any of the above examples, wherein the variation in the geometric feature comprises a difference between the geometric feature of the sample and a saved geometric feature stored in a memory of the system.

Example 63: the system of example 62, wherein the saved geometric feature comprises a reference geometric feature provided by a user.

Example 64: the system of example 62, wherein the saved geometric feature comprises a geometric feature previously determined by the system.

Example 65: the system of example 64, wherein the previously determined geometric feature is a feature of the second sample after performing the first manufacturing step on the second sample.

Example 66: the system of example 5, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool downstream of a fabrication process performed by the fabrication system.

Example 67: the system of example 6, wherein the one or more hardware processors are configured to output the indication of the unplanned variation to a sample processing tool for performing the first manufacturing step.

Example 68: a method of determining the size of a sample using second harmonic generation, the method comprising:

receiving a first SHG signal;

changing at least one parameter of the light beam of at least one light source or an optical detection system;

receiving a second SHG signal after the variation of the at least one parameter;

the geometry of the feature of the sample is determined based on the first SHG signal and the second SHG signal.

Example 69: the method of example 59, wherein the geometry comprises a size or shape.

Example 70: a system for characterizing a sample using second harmonic generation, the system comprising:

a sample support configured to support a sample;

at least one light source configured to direct a beam of light onto the sample to generate a Second Harmonic Generation (SHG) signal;

an optical detection system comprising at least one detector configured to receive the SHG signal emitted from the sample and to generate a detected SHG signal;

receiving a first detected SHG signal from the optical detection system, the first detected SHG signal collected by the at least one detector at a first angle relative to a characteristic of the sample;

receiving a second detected SHG signal from the optical detection system, the second detected SHG signal collected by the at least one detector at a second angle relative to the feature of the sample, the second angle different from the first angle; and

The size of the feature of the sample is determined based on the first detected SHG signal and the second detected SHG signal.

Example 71: a system for characterizing a sample using second harmonic generation, the system comprising:

A sample support configured to support a sample;

receiving at least one first detected SHG signal;

determining a change in a characteristic of the first detected SHG signal or the sample; and

An indication of the change is output.

Example 72: the system of example 71, wherein the change is associated with a change in a geometric characteristic of the sample.

Example 73: the system of example 71, wherein the change is associated with a change in a size or shape of the sample.

Example 74: the system of example 72, wherein the variation in the geometric characteristic of the sample comprises a difference between the geometric characteristic of the sample and a saved geometric characteristic stored in a memory of the system.

Example 75: the system of example 74, wherein the saved geometric feature comprises a reference geometric feature provided by a user.

Example 76: the system of example 74, wherein the saved geometric feature is determined by the system prior to determining the change.

Example 77: the system of any of examples 74-76, wherein the saved geometric feature comprises a size or shape of a device.

Example 78: the system of any of the above examples, wherein the one or more hardware processors receive the at least one detected SHG signal after performing the first manufacturing step on the sample.

Example 79: the system of example 78, wherein the saved geometric feature is a geometric feature of the second sample after performing the first manufacturing step on the second sample.

Example 80: the system of any of the above examples, wherein the system is included in-line in a manufacturing system.

Example 81: the system of example 80, wherein the first manufacturing step is a step in a manufacturing process performed by the manufacturing system.

Example 82: the system of any of examples 71 to 81, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in the sample associated with the change.

Example 83: the system of example 78, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool for performing a second manufacturing step on the sample after the first manufacturing step to adjust for the unplanned variation in the sample.

Example 84: the system of any of examples 71 to 81, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in samples associated with the change in subsequently manufactured samples.

Example 85: the system of any one of examples 71 to 81, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool downstream of the manufacturing process.

Example 86: the system of any one of examples 71 to 81, wherein the one or more hardware processors are configured to output an indication of the change to the sample processing tool to thereby cause an adjustment to adjust the sample processing tool.

Example 87: the system of example 78, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool for performing the first manufacturing step.

Example 88: the system of any one of examples 71-86, further comprising a second detected SHG signal, the plurality of first and second detected SHG signals measured with at least one measurement parameter that is different for the plurality of first and second detected SHG signals, and the one or more hardware processors configured to:

Receiving the plurality of first and second detected SHG signals; and

A variation in a characteristic of the sample is determined based on the first detected SHG signal and the second detected SHG signal.

Example 89: the system of example 88, wherein the at least one parameter comprises at least one of a measurement location, a measurement angle, a polarization, or a wavelength.

Example 90: the system of any one of examples 88 to 89, wherein the at least one parameter comprises a tilt angle of the measured SHG signal relative to the sample.

Example 91: the system of any of examples 88 to 90, wherein the at least one parameter comprises a tilt angle of the at least one detector relative to the sample.

Example 92: the system of any one of examples 88 to 91, wherein the at least one measurement parameter comprises an azimuth angle of the measured SHG signal relative to an axis perpendicular to a surface of the sample.

Example 93: the system of any of examples 88 to 92, wherein the at least one measurement parameter comprises an azimuth angle of the at least one detector relative to an axis perpendicular to a surface of the sample.

Example 94: the system of any one of examples 88 to 93, wherein the at least one measurement parameter comprises polarization of the plurality of SHG signals received by the at least one optical detector.

Example 95: the system of any of examples 88 to 94, wherein the at least one measurement parameter comprises a polarization of a polarizer of the at least one detector.

Example 96: the system of any of examples 88 to 95, wherein the at least one measurement parameter comprises a polarization of the light beam incident on the sample.

Example 97: the system of any of examples 88 to 96, wherein the at least one measurement parameter comprises an inclination angle of the at least one light beam directed at the sample relative to the sample.

Example 98: the system of any of examples 88 to 97, wherein the at least one measurement parameter comprises an azimuthal angle of the at least one light beam directed on the sample relative to an axis perpendicular to a surface of the sample.

Example 99: the system of any of examples 88 to 98, wherein the at least one measurement parameter comprises a wavelength of the at least one light beam directed onto the sample.

Example 100: the system of any of examples 88 to 99, wherein the at least one measurement parameter comprises an output wavelength of the at least one light source.

Example 101: the system of any of examples 88 to 100, wherein the at least one measurement parameter comprises a detection wavelength of the at least one detector.

Example 102: the system of any of examples 88 to 101, wherein the at least one measurement parameter comprises a wavelength of an SHG signal received by the at least one optical detector.

Example 103: the system of any of examples 88 to 102, wherein the sample is configured to rotate relative to the incident light beam and/or the at least one detector.

Example 104: the system of any of examples 88 to 103, wherein the at least one measurement parameter comprises an angle of at least one detector that receives the SHG signal propagating in a plane formed by the light beam and an axis perpendicular to the sample.

Example 105: the system of any of examples 88 to 104, wherein the at least one parameter comprises an angle of at least one detector that receives an SHG signal propagating out of a plane formed by the light beam and an axis perpendicular to the sample.

Example 106: the system of any of examples 88 to 105, wherein the at least one parameter comprises a linear or circular polarization of a light beam of the at least one light source.

Example 107: the system of any of examples 88 to 106, wherein at least one light source comprises a broadband light source.

Example 108: the system of any of examples 88 to 107, wherein the at least one light source comprises at least two different wavelength light sources.

Example 109: the system of any of examples 88 to 108, wherein the system is configured to change the at least one metrology parameter.

Example 110: the system of example 109, wherein to change the at least one metrology parameter, the one or more hardware processors are configured to cause the at least one light source to simultaneously emit a plurality of wavelengths.

Example 111: the system of example 109, wherein to change the at least one metrology parameter, the one or more hardware processors are configured to cause the at least one light source to emit different wavelengths at different times.

Example 112: the system of any of examples 88 to 111, wherein the at least one parameter comprises an angle of the at least one detected SHG signal and a polarization of the detected SHG signal.

Example 113: the system of any of the above examples, wherein the system is included in-line in a semiconductor device manufacturing system.

Example 114: the system of any of the above examples, wherein the feature comprises a feature of one or more integrated circuit devices or one or more partially completed integrated circuit devices or portions thereof.

Example 115: the system of any of the above examples, wherein the feature comprises a geometric feature of one or more finfets, GAA, tri-gates, or NAND structures.

Example 116: the system of any of the above examples, wherein the features comprise geometric features of one or more three-dimensional structures of the sample.

Example 117: the system of any of the above examples, wherein the at least one light source comprises a first light source configured to emit detection radiation and a second light source configured to emit pump radiation.

Example 118: the system of any of the above examples, further comprising a corona gun configured to deposit different amounts of charge to a top side of the sample.

Example 119: the system of example 100, wherein the one or more hardware processors are configured to determine characteristics of the at least one detected SHG signal, the first detected SHG signal, or the second detected SHG signal for different amounts of charge.

Example 120: the system of any one of the above claims, wherein the sample comprises a semiconductor.

Example 121: the system of any of the above examples, wherein the at least one light source comprises a first light source configured to emit a first light beam of a first wavelength and a second light source configured to emit a second light beam of a second wavelength.

Example 122: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive an SHG signal at a first angle and a second detector configured to receive the SHG signal at a second angle.

Example 123: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive the SHG signal of a first polarization and a second detector configured to receive the SHG signal of a second polarization.

Example 124: the system of any of the above examples, wherein the at least one detector comprises a detector array comprising a number of pixels.

Example 125: the system of any of the above examples, wherein the at least one detector comprises a 1D detector array.

Example 126: the system of any of the above examples, wherein the at least one detector comprises a 2D detector array.

Example 127: the system of any one of examples 124-126, further comprising at least one lens configured to direct SHG signals emitted from a sample at different angles to different locations on the detector array.

Example 128: a system for characterizing a sample using second harmonic generation, the system comprising:

a sample support configured to support a sample;

an optical detection system comprising at least one detector configured to receive an SHG signal from the sample and to generate a detected SHG signal;

receiving a first detected SHG signal;

determining a change in the detected first SHG signal; and

An indication of the change is output.

Example 129: the system of example 128, wherein the change is associated with a change in a geometric characteristic of the sample.

Example 130: the system of example 128, wherein the change is associated with a change in a size or shape of the sample.

Example 131: the system of any of examples 128-130, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in the sample associated with the change.

Example 132: the system of any of examples 128-131, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in samples associated with the change in subsequently manufactured samples.

Example 133: the system of any of examples 128-132, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool downstream of the manufacturing process.

Example 134: the system of any of examples 128-133, wherein the one or more hardware processors are configured to output an indication of the change to the sample processing tool to thereby cause an adjustment to adjust the sample processing tool.

Example 135: the system of any one of examples 1 to 67 and 70 to 134, wherein the system further comprises another metering system.

Example 136: the system of any one of examples 1 to 67 and 70 to 134, wherein the system further comprises another optical metrology system.

Example 137: the system of any one of examples 1-67 and 70-134, wherein the system further comprises another metering system configured to determine a geometric feature or a change in geometric feature of the sample.

Example 138: the system of any one of examples 1 to 67 and 70 to 134, wherein the system further comprises another optical metrology system configured to determine a geometric feature or a change in geometric feature of the sample using light from the sample.

Example 139: the system of any one of examples 1-67 and 70-134, wherein the system further comprises an optical scatterometry system configured to determine a geometric feature or a change in geometric feature of the sample using light scattered from the sample, the wavelength of the scattered light being the same as the wavelength of the light source beam.

Example 140: the system of examples 138 or 139, wherein the light source beam is generated by at least one light source.

Example 141: the system of example 138 or 139, wherein the light source beam is generated by a second light source.

Example 142: the system of any of examples 139-141 wherein the at least one optical detector is further configured to receive light scattered from the sample.

Example 143: the system of any one of examples 1-67 and 70-142, wherein the at least one optical detector is further configured to detect light having a dominant wavelength, wherein the dominant wavelength is a wavelength of the light beam or the source light beam.

Example 144: the system of any of examples 139-141 wherein light scattered from the sample is detected by a second detector.

Example 145: the system of any of examples 18 to 65, wherein the one or more hardware processors are further configured to distinguish between variations in different geometric characteristics of the one or more devices on the sample.

Example 146: the system of any of examples 18-65, wherein the plurality of first detected SHG signals are dependent on first and second geometric features such that a variation of the first feature causes a variation of the first detected SHG signal and a variation of the second feature causes a variation of the first detected SHG signal.

Example 147: the system of example 146, wherein the one or more hardware processors are further configured to distinguish between variations of the plurality of first and second features using the plurality of first and second detected SHG signals.

Example 148: the system of any of examples 145-147, wherein the different geometric features include a height and a width of the one or more devices.

Example 149: the system of any of the above examples, wherein the geometric feature comprises a geometric feature in a region of the sample illuminated by the light beam.

Example 150: the system of example 149, wherein the illuminated region of the sample comprises a portion of the periodic structure that is greater than a single period.

Example 151: the system of example 150, wherein the geometric feature comprises a geometric feature in a cycle.

Example 152: the system of example 151, wherein the periodic structure includes an array of transistors and the geometric feature includes a width or a height of transistors in the array of transistors.

Example 153: the system of any one of examples 1-67, wherein the one or more hardware processors are configured to determine a geometric feature of the sample based on the at least one detected SHG signal.

Example 154: the system of any one of examples 1-67, wherein the one or more hardware processors are configured to determine a change in a geometric characteristic of the sample based on the at least one detected SHG signal.

Example 155: the system of any of examples 18-67, wherein the one or more hardware processors are configured to determine the geometric feature of the sample based on the first detected SHG signal and the second detected SHG signal.

Example 156: the system of any of examples 18-67, wherein the one or more hardware processors are configured to determine a change in a geometric characteristic of the sample based on the first detected SHG signal and the second detected SHG signal.

Example 157: the system of any one of examples 71 to 127, wherein the one or more hardware processors are configured to:

receiving at least one first detected SHG signal;

determining a change in the first detected SHG signal; and

An indication of the change is output.

Example 158: the system of any one of examples 71 to 127, wherein the one or more hardware processors are configured to:

receiving at least one first detected SHG signal;

determining a change in a characteristic of the sample; and

An indication of the change is output.

Group 2

An optical detection system comprising at least one optical detector configured to receive the SHG signal emitted from the sample and to generate a detected SHG signal;

receiving at least one detected SHG signal; and

Example 2: the system of example 1, wherein the geometric feature of the sample is determined based at least in part on a mapping of the detected SHG signal to geometric features of one or more structures on the sample that are completed or have not been completed.

Identifying an unintended variation of the geometric feature of the sample; and

An indication of the unplanned variation is output.

Example 9: the system of example 6, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a user via a user interface of the system.

receiving the plurality of first and second detected SHG signals; and

Example 32: the system of any one of examples 18-31, wherein the at least one measurement parameter comprises a wavelength of the SHG signal received by the at least one optical detector.

Example 34: the system of any of examples 18-33, wherein the at least one measurement parameter comprises an angle of the at least one detector that receives an SHG signal propagating in a plane formed by the light beam and an axis perpendicular to the sample.

Example 36: the system of any of examples 18-35, wherein the at least one parameter comprises a parameter of a linearly or circularly polarized light beam of the at least one light source.

Example 53: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive an SHG signal at a first angle and a second detector configured to receive an SHG signal at a second angle.

Example 66: the system of example 5, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool downstream in a manufacturing process performed by the manufacturing system.

receiving a first SHG signal;

changing at least one parameter of the light beam of the at least one light source or the optical detection system;

Receiving at least one first detected SHG signal;

An indication of the change is output.

Example 79: the system of example 78, wherein the saved geometric feature is a second geometric feature of a second sample after performing the first manufacturing step on the second sample.

receiving the plurality of first and second detected SHG signals; and

Example 90: the system of any of examples 88 to 89, wherein the at least one parameter comprises a tilt angle of the measured SHG signal relative to the sample.

Example 98: the system of any of examples 88 to 97, wherein the at least one measurement parameter comprises an azimuth angle of the at least one light beam directed on the sample relative to an axis perpendicular to a surface of the sample.

Example 104: the system of any of examples 88 to 103, wherein the at least one metrology parameter comprises an angle of at least one detector receiving an SHG signal propagating in a plane formed by the light beam and an axis perpendicular to the sample.

Example 105: the system of any of examples 88 to 104, wherein the at least one parameter comprises an angle of at least one detector that receives the SHG signal propagating out of a plane formed by the light beam and an axis perpendicular to the sample.

Example 122: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive the SHG signal at a first angle and a second detector configured to receive the SHG signal at a second angle.

receiving a first detected SHG signal;

determining a change in the detected first SHG signal; and

An indication of the change is output.

Example 135: the system of any one of examples 1-67 and 70-134, wherein the system further comprises a sample support configured to support a sample.

Example 136: the system of any one of examples 1 to 67 and 70 to 135, wherein the system further comprises another metering system.

Example 137: the system of any one of examples 1 to 67 and 70 to 135, wherein the system further comprises another optical metrology system.

Example 138: the system of any one of examples 1-67 and 70-135, wherein the system further comprises another metrology system configured to determine a geometric feature or a change in a geometric feature of the sample.

Example 139: the system of any one of examples 1-67 and 70-135, wherein the system further comprises another optical metrology system configured to determine a geometric feature or a change in a geometric feature of the sample using light from the sample.

Example 140: the system of any one of examples 1-67 and 70-135, wherein the system further comprises an optical scatterometry system configured to determine a geometric feature or a change in geometric feature of the sample using light scattered from the sample, the wavelength of the scattered light being the same as the wavelength of the light source beam.

Example 141: the system of example 139 or 140, wherein the light source beam is generated by at least one light source.

Example 142: the system of example 139 or 140, wherein the light source beam is generated by a second light source.

Example 143: the system of any of examples 140-142, wherein the at least one optical detector is further configured to receive light scattered from the sample.

Example 144: the system of any one of examples 1-67 and 70-143, wherein at least one optical detector is further configured to detect light having a dominant wavelength, wherein the dominant wavelength is a wavelength of the light beam or the source light beam.

Example 145: the system of any of examples 139-144 wherein light scattered from the sample is detected by a second detector.

Example 146: the system of any of examples 18 to 65, wherein the one or more hardware processors are further configured to distinguish between variations in different geometric characteristics of the one or more devices on the sample.

Example 147: the system of any of examples 18-65, wherein the plurality of first detected SHG signals are dependent on first and second geometric features such that a variation of the first feature causes a variation of the first detected SHG signal and a variation of the second feature causes a variation of the first detected SHG signal.

Example 148: the system of example 147, wherein the one or more hardware processors are further configured to distinguish between variations of the plurality of first and second features using the plurality of first and second detected SHG signals.

Example 149: the system of any of examples 146-148, wherein the different geometric features include a height and a width of one or more devices.

Example 150: the system of any of the above examples, wherein the geometric feature comprises a geometric feature in a region of the sample illuminated by the light beam.

Example 151: the system of example 150, wherein the illuminated region of the sample comprises a portion of the periodic structure that is greater than a single period.

Example 152: the system of example 151, wherein the geometric feature comprises a geometric feature in a cycle.

Example 153: the system of example 152, wherein the periodic structure includes an array of transistors and the geometric feature includes a width or a height of transistors in the array of transistors.

Example 154: the system of any one of examples 1-67, wherein the one or more hardware processors are configured to determine a geometric feature of the sample based on the at least one detected SHG signal.

Example 155: the system of any one of examples 1-67, wherein the one or more hardware processors are configured to determine a change in a geometric characteristic of the sample based on the at least one detected SHG signal. Example 156: the system of any of examples 18-67, wherein the one or more hardware processors are configured to determine the geometric feature of the sample based on the first detected SHG signal and the second detected SHG signal.

Example 157: the system of any of examples 18-67, wherein the one or more hardware processors are configured to determine a change in a geometric characteristic of the sample based on the first detected SHG signal and the second detected SHG signal.

receiving at least one first detected SHG signal;

determining a change in the first detected SHG signal; and

An indication of the change is output.

Example 159: the system of any one of examples 71 to 127, wherein the one or more hardware processors are configured to:

receiving at least one first detected SHG signal;

determining a change in a characteristic of the sample; and

An indication of the change is output.

Group 3

Example 1: a system for optically interrogating a surface, comprising:

a pump light source configured to emit pump radiation, the pump radiation having an average optical pump power;

a detection light source configured to emit detection radiation having an average optical detection power that is less than the average optical pump power;

at least one optical detector configured to detect light generated by a second harmonic generated by at least one of the pump radiation or the probe radiation, the second harmonic generated light generated by a semiconductor wafer whose surface is to be interrogated;

At least one of a shutter, a modulator or a variable optical path configured to introduce a variable time offset between the pump radiation and the detection radiation; and

A processor configured to determine a characteristic of the light produced by the detected second harmonic,

wherein the system is configured to obtain the time dependence of the detected second harmonic generated light in less than 10 seconds after application of at least one of the pump radiation and the probe radiation.

Example 2: the system of example 1, wherein the pump light source comprises a UV flash.

Example 3: the system of example 1, wherein the pump light source comprises a laser.

Example 4: the system of example 3, wherein the pump light source comprises a pulsed laser.

Example 5: the system of example 4, wherein the pulsed laser is selected from the group consisting of nanosecond, picosecond, and femtosecond lasers.

Example 6: the system of example 4, wherein the pulsed laser comprises a wavelength tunable laser.

Example 7: the system of example 1, wherein the detection light source comprises a pulsed laser.

Example 8: the system of example 1, wherein the optical detector is selected from the group consisting of a photomultiplier tube, a CCD camera, a burst detector, a photodiode detector, a high-speed scanning camera, and a silicon detector.

Example 9: the system of example 8, wherein the system is configured to obtain the second harmonic generated light in less than 1 second after applying at least one of the pump radiation and the probe radiation.

Example 10: the system of example 1, wherein the system comprises a variable optical path configured to introduce a variable time offset between the pump radiation and the detection radiation.

Example 11: the system of example 10, wherein the variable optical path is programmable optical delay.

Example 12: the system of example 1, wherein the shutter is an optical shutter selected from the group consisting of kerr boxes and pockels boxes.

Example 13: the system of example 1, wherein the shutter is a mechanical shutter.

Example 14: the system of example 1, wherein the shutter is configured to introduce a time offset of between about 1 millisecond and about 60 seconds.

Example 15: the system of example 1, wherein the processor is configured to obtain the time dependence of the detected second harmonic generated light in less than 10 seconds after application of the at least one of the pump radiation and the probe radiation.

Example 16: the system of example 1, wherein the processor is configured to determine a characteristic of the detected second harmonic generated light, including a decrease in intensity of the detected second harmonic generated light in the presence of pump energy.

Example 17: the system of example 1, wherein the processor is configured to determine a characteristic of the detected second harmonic generated light, including an increase in intensity of the detected second harmonic generated light in the presence of pump energy.

Example 18: the system of example 1, wherein the variable optical path comprises an optical delay line.

Example 19: the system of example 18, wherein the optical delay line comprises at least one of a fiber-based device, a mirror-based device, a number of set-time delay lines, or a variable delay line.

Example 20: the system of example 1, wherein the processor is further configured to determine the characteristic of the surface based on the detected light generated by the second harmonic and the variable time offset.

Example 21: the system of example 1, wherein the average optical pump power is less than 10W.

Example 22: the system of example 1, wherein the average optical detection power is less than 150mW.

Example 23: the system of example 1, wherein the pump radiation comprises a number of optical pulses having a peak optical pump power, and wherein the probe radiation comprises a number of optical pulses having a peak optical probe power greater than the peak optical pump power.

Example 24: a system for optically interrogating a surface, comprising:

at least one optical detector configured to detect light generated by a second harmonic generated by at least one of the pump radiation or the probe radiation, the second harmonic generated light generated by a semiconductor wafer whose surface is to be interrogated; and

A controller configured to obtain information about a time dependence of the detected second harmonic generated light generated within less than 10 seconds after application of at least one of the pump radiation and the probe radiation.

Example 25: the system of example 24, wherein the average optical pump power is less than 10W.

Example 26: the system of example 24, wherein the average optical detection power is less than 150mW.

Example 27: the system of example 24, wherein the pump radiation comprises a number of optical pulses having a peak optical pump power, and wherein the probe radiation comprises a number of optical pulses having a peak optical probe power greater than the peak optical pump power.

Example 28: a system for optically interrogating a surface, comprising:

a pump light source configured to emit pump radiation having a variable energy, the pump radiation having an average optical pump power;

an optical detector configured to detect light generated by a second harmonic generated by at least one of the pump radiation or the probe radiation, the second harmonic generated light generated by a semiconductor wafer whose surface is to be interrogated; and

Processing electronics configured to:

obtaining information about a time dependence of light generated by the detected second harmonic within less than 10 seconds after application of at least one of the pump radiation and the probe radiation; and

Discontinuous regions in the light generated by the second harmonic are detected to determine the threshold injected carrier energy as the energy of the pump radiation changes.

Example 29: the system of example 28, wherein the intensity of the light produced by the second harmonic increases as the energy of the pump radiation increases after the discontinuous region.

Example 30: the system of example 28, wherein the average optical pump power is less than 10W.

Example 31: the system of example 28, wherein the average optical detection power is less than 150mW.

Example 32: the system of example 28, wherein the pump radiation comprises a number of optical pulses having a peak optical pump power, and wherein the probe radiation comprises a number of optical pulses having a peak optical probe power that is greater than the peak optical pump power.

Any one or more of the instances in group 3 may be combined with any one or more of the instances in groups 1, 2, or 4. For example, any of the systems in group 3 may be further configured to receive at least one detected SHG signal and determine a geometric feature of the sample based on the at least one detected SHG signal. In addition, any of the systems in group 3 may be further configured to receive at least one detected SHG signal and determine a change in a geometric characteristic of the sample based on the at least one detected SHG signal. In addition, any of the systems in group 3 may be further configured to receive at least one first detected SHG signal, determine a change in the first detected SHG signal, and output an indication of the change. Any of the systems in group 3 may be further configured to receive at least one first detected SHG signal, determine a change in a characteristic of the sample, and output an indication of the change. In addition, any of the systems in group 3 may be further configured to identify an unplanned variation in the geometric characteristics of the sample and output an indication of the unplanned variation.

Additional examples in groups 1, 2, and 4 may be combined with any one or more of the examples listed in group 3.

Group 4

a sample support configured to support a sample;

at least one light source configured to direct a beam of light onto the sample to generate Second Harmonic Generation (SHG);

an optical detection system comprising at least one optical detector configured to receive light generated by a second harmonic from the sample;

receiving at least one SHG signal; and

Determining a geometric feature of the sample or a variation of the geometric feature of the sample based on the at least one SHG signal.

Example 2: the system of any of the above examples, wherein the geometric feature of the sample is determined based at least in part on an image of the SHG signal and a geometric feature of the integrated circuit device or one or more portions of the integrated circuit device that have completed or have not completed.

Example 3: the system of example 2, wherein the image is generated based on empirical data.

Example 4: the system of example 2, wherein the map is generated via a machine learning algorithm.

Example 5: the system of example 2, wherein the map comprises a look-up table of SHG signal values and geometric features.

identifying unplanned variations in the geometric characteristics of the sample; and

An indication of the unplanned variation is output.

Example 7: the system of example 6, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool configured to adjust for the unplanned variation in the sample.

Example 8: the system of example 6 or 7, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool downstream of the manufacturing process.

Example 9: the system of example 6, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a user.

Example 18: the system of any of the above examples, wherein the at least one SHG signal comprises first and second signals measured with at least one measurement parameter that is different for the first and second SHG signals, and the one or more hardware processors are configured to:

receiving the plurality of first and second SHG signals; and

Determining a geometric feature of the sample or a variation in the geometric feature of the sample based on the first SHG signal and the second SHG signal.

Example 19: the system of example 18, wherein the at least one parameter comprises at least one of a measurement location, a measurement angle, a polarization, or a wavelength.

Example 20: the system of any of examples 18-19, wherein the at least one parameter comprises a tilt angle of the measured SHG light relative to the sample.

Example 21: the system of any of examples 18 to 20, wherein the at least one parameter comprises an inclination angle of the at least one detector relative to the sample.

Example 22: the system of any of examples 18-21, wherein the at least one measurement parameter comprises an azimuth angle of the measured SHG light relative to the sample.

Example 23: the system of any of examples 18 to 22, wherein the at least one measurement parameter comprises an azimuth angle of at least one detector relative to the sample.

Example 24: the system of any one of examples 18 to 23, wherein the at least one measurement parameter comprises polarization of the measured SHG light.

Example 25: the system of any of examples 18 to 24, wherein the at least one measurement parameter comprises a polarization of at least one detector.

Example 26: the system of any of examples 18 to 25, wherein the at least one measurement parameter comprises polarization of a light beam incident on the sample.

Example 27: the system of any of examples 18 to 26, wherein the at least one measurement parameter comprises an inclination angle of at least one light beam directed at the sample relative to the sample.

Example 28: the system of any of examples 18 to 27, wherein the at least one measurement parameter comprises an azimuth angle of at least one light beam directed at the sample relative to the sample.

Example 29: the system of any of examples 18 to 28, wherein the at least one measurement parameter comprises a wavelength of at least one light beam directed onto the sample.

Example 30: the system of any of examples 18 to 29, wherein the at least one measurement parameter comprises an output wavelength of at least one light source.

Example 31: the system of any of examples 18 to 30, wherein the at least one measurement parameter comprises a detection wavelength of at least one detector.

Example 32: the system of any of examples 18-31, wherein the at least one measurement parameter comprises a wavelength of the measured SHG light.

Example 33: the system of any of examples 18 to 32, wherein the sample is configured to rotate relative to the incident light beam and/or the at least one detector.

Example 34: the system of any of examples 18 to 33, wherein the at least one measurement parameter comprises an angle of at least one detector in a plane with the sample.

Example 35: the system of any of examples 18 to 34, wherein the at least one parameter comprises an angle of at least one detector out of plane with the sample.

Example 36: the system of any of examples 18 to 35, wherein the at least one parameter comprises a linear or circular polarization of a light beam of the at least one light source.

Example 43: the system of any of the above examples, wherein the system is included in-line in a manufacturing system.

Example 50: the system of example 49, wherein the one or more hardware processors are configured to determine characteristics of the first or second SHG signals for different amounts of charge.

Example 59: a method of determining the size of a sample using second harmonic generation, the method comprising:

Receiving a first SHG signal;

the geometry of the feature of the sample is determined based on the first SHG signal, the second SHG signal, and a mapping of SHG signals to the geometry of the feature of the sample.

Example 60: the method of example 59, wherein the geometry comprises a size or shape.

Example 61: a system for characterizing a sample using second harmonic generation, the system comprising:

a sample support configured to support a sample;

an optical detection system comprising at least one detector configured to receive light generated by a second harmonic from the sample;

receiving a first SHG signal from the optical detection system, the first SHG signal collected by the at least one detector at a first angle relative to a characteristic of the sample;

Receiving a second SHG signal from the optical detection system, the second SHG signal collected by the at least one detector at a second angle relative to the feature of the sample, the second angle different from the first angle; and

The size of the feature of the sample is determined based on the first SHG signal, the second SHG signal, and a mapping of a SHG signal to the size of the feature of the sample.

Example 62: a system for characterizing a sample using second harmonic generation, the system comprising:

a sample holder configured to hold a sample;

receiving at least one first SHG signal;

determining a change in a characteristic of the first SHG signal or the sample; and

An indication of the change is output.

Example 63: the system of example 62, wherein the change is associated with a change in a geometric characteristic of the sample.

Example 64: the system of example 62, wherein the change is associated with a change in a size or shape of the sample.

Example 65: the system of any of examples 62 to 64, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in the sample associated with the change.

Example 66: the system of any of examples 62 to 65, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in samples associated with the change in subsequently manufactured samples.

Example 67: the system of any of examples 62 to 66, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool downstream of the manufacturing process.

Example 68: the system of any of examples 62 to 67, wherein the one or more hardware processors are configured to output an indication of the change to the sample processing tool to thereby cause an adjustment to adjust the sample processing tool.

Example 69: the system of any of examples 62 to 68, further comprising a second SHG signal, the plurality of first and second signals measured with at least one measurement parameter that is different for the first and second SHG signals, and the one or more hardware processors configured to:

Receiving the plurality of first and second SHG signals; and

A variation in a characteristic of a sample is determined based on the first SHG signal and the second SHG signal.

Example 70: the system of example 69, wherein the at least one parameter comprises at least one of a measurement location, a measurement angle, a polarization, or a wavelength.

Example 71: the system of any one of examples 69 to 70 wherein the at least one parameter comprises a tilt angle of the measured SHG light relative to the sample.

Example 72: the system of any one of examples 69 to 71 wherein the at least one parameter comprises an inclination angle of the at least one detector relative to the sample.

Example 73: the system of any one of examples 69 to 72 wherein the at least one measurement parameter comprises an azimuth angle of the measured SHG light relative to the sample.

Example 74: the system of any one of examples 69 to 73 wherein the at least one measurement parameter comprises an azimuth angle of at least one detector relative to the sample.

Example 75: the system of any one of examples 69 to 74 wherein the at least one measurement parameter comprises polarization of the measured SHG light.

Example 76: the system of any one of examples 69 to 75 wherein the at least one measurement parameter comprises a polarization of at least one detector.

Example 77: the system of any of examples 69 to 76 wherein the at least one measurement parameter comprises polarization of a beam of light incident on the sample.

Example 78: the system of any of examples 69 to 77, wherein the at least one measurement parameter comprises an inclination angle of at least one light beam directed at the sample relative to the sample.

Example 79: the system of any of examples 69 to 78 wherein the at least one measurement parameter comprises an azimuth angle of at least one light beam directed at the sample relative to the sample.

Example 80: the system of any of examples 69 to 79 wherein the at least one measurement parameter comprises a wavelength of at least one light beam directed onto the sample.

Example 81: the system of any one of examples 69 to 80 wherein the at least one measurement parameter comprises an output wavelength of at least one light source.

Example 82: the system of any one of examples 69 to 81 wherein the at least one measurement parameter comprises a detection wavelength of at least one detector.

Example 83: the system of any one of examples 69 to 82 wherein the at least one measurement parameter comprises a wavelength of the measured SHG light.

Example 84: the system of any one of examples 69 to 83, wherein the sample is configured to rotate relative to the incident light beam and/or the at least one detector.

Example 85: the system of any one of examples 69 to 84 wherein the at least one measurement parameter comprises an angle of at least one detector in a plane having the sample.

Example 86: the system of any one of examples 69 to 85 wherein the at least one parameter comprises an angle of at least one detector out of plane with the sample.

Example 87: the system of any of examples 69 to 86, wherein the at least one parameter comprises a linear or circular polarization of a light beam of the at least one light source.

Example 88: the system of any one of examples 69 to 87, wherein the at least one light source comprises a broadband light source.

Example 89: the system of any one of examples 69 to 88 wherein the at least one light source comprises at least two different wavelength light sources.

Example 90: the system of any one of examples 69 to 89 wherein the system is configured to change the at least one metrology parameter.

Example 91: the system of example 90, wherein to change the at least one metrology parameter, the one or more hardware processors are configured to cause the at least one light source to simultaneously emit a plurality of wavelengths.

Example 92: the system of example 90, wherein to change the at least one metrology parameter, the one or more hardware processors are configured to cause the at least one light source to emit different wavelengths at different times.

Example 93: the system of any one of examples 69 to 92 wherein the at least one parameter includes an angle of the at least one detected SHG signal and a polarization of the detected SHG signal.

Example 94: the system of any of the above examples, wherein the system is included in-line in a manufacturing system.

Example 95: the system of any of the above examples, wherein the system is included in-line in a semiconductor device manufacturing system.

Example 96: the system of any of the above examples, wherein the feature comprises a feature of one or more integrated circuit devices or one or more partially completed integrated circuit devices or portions thereof.

Example 97: the system of any of the above examples, wherein the feature comprises a geometric feature of one or more finfets, GAA, tri-gates, or NAND structures.

Example 98: the system of any of the above examples, wherein the features comprise geometric features of one or more three-dimensional structures of the sample.

Example 99: the system of any of the above examples, wherein the at least one light source comprises a first light source configured to emit detection radiation and a second light source configured to emit pump radiation.

Example 100: the system of any of the above examples, further comprising a corona gun configured to deposit different amounts of charge to a top side of the sample.

Example 101: the example 100 system, wherein the one or more hardware processors are configured to determine characteristics of the first or second SHG signals for different amounts of charge.

Example 102: the system of any of the above examples, wherein the sample comprises a semiconductor.

Example 103: the system of any of the above examples, wherein the at least one light source comprises a first light source configured to emit a first light beam of a first wavelength and a second light source configured to emit a second light beam of a second wavelength.

Example 104: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive SHG signals at a first angle and a second detector configured to receive SHG signals at a second angle.

Example 105: the system of any of the above examples, wherein the at least one detector comprises a first detector configured to receive the SHG signal of a first polarization and a second detector configured to receive the SHG signal of a second polarization.

Example 106: the system of any of the above examples, wherein the at least one detector comprises a detector array comprising a number of pixels.

Example 107: the system of any of the above examples, wherein the at least one detector comprises a 1D detector array.

Example 108: the system of any of the above examples, wherein the at least one detector comprises a 2D detector array.

Example 109: the system of any one of examples 106-108, further comprising at least one lens configured to direct SHG signals emitted from a sample at different angles to different locations on the detector array.

Example 110: a system for characterizing a sample using second harmonic generation, the system comprising:

a sample support configured to support a sample;

receiving a first SHG signal;

determining a change in the first SHG signal; and

An indication of the change is output.

Example 111: the system of example 110, wherein the change is associated with a change in a geometric characteristic of the sample.

Example 112: the system of example 110, wherein the change is associated with a change in a size or shape of the sample.

Example 113: the system of any of examples 110 to 112, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in the sample associated with the change.

Example 114: the system of any of examples 110 to 113, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool configured to adjust for errors in samples associated with the change in subsequently manufactured samples.

Example 115: the system of any of examples 110 to 114, wherein the one or more hardware processors are configured to output an indication of the change to a sample processing tool downstream of the manufacturing process.

Example 116: the system of any of examples 110 to 115, wherein the one or more hardware processors are configured to output an indication of the change to the sample processing tool to thereby cause an adjustment to adjust the sample processing tool.

Terminology

Details of exemplary inventive embodiments and selection of features have been set forth above. As for other details, such may be appreciated in conjunction with the patents and publications cited above, and are generally known or understood by those skilled in the art. The same applies with respect to the method-based aspects of the present invention in terms of additional actions as commonly or logically employed. With respect to such methods, including methods of manufacture and use, such may be practiced in any order of events that is logically possible and in any order of events recited. Furthermore, where a range of values is provided, it is understood that each intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. Moreover, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein.

The phrase "at least one" in a list of items, as used herein, refers to any combination of these items, including a single component. As an example, "at least one of a, b, or c" is intended to encompass: a. b, c, a-b, a-c, b-c, and a-b-c.

While embodiments of the invention have been described with reference to several examples of various features incorporated as appropriate, they are not limited to what has been described or indicated as contemplated with respect to each such variation. Changes may be made to any of the described embodiments of this invention and equivalents may be substituted (whether described herein or not included for brevity) without departing from the true spirit and scope of their etc. The specific features described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

The various illustrative processes described may be implemented or performed using a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may be part of a computer system that also has a user interface port that communicates with the user interface and receives commands entered by a user, at least one memory (e.g., hard disk drive or other comparable storage, and random access memory) that stores electronic information including programs that are under the control of the processor and that operate in communication via the user interface port, and a video output that generates its output via any kind of video output format (e.g., VGA, DVI, HDMI, displayPort or any other form).

A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Such devices may also be used to select values for devices as described herein.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), flash memory, read-only memory (ROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), a buffer, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more example embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof, etc. If implemented in software, the functions may be stored as one or more instructions, program code or other information on a computer-readable medium via which the analysis/calculation data is transmitted or caused to be output. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory storage may also be a rotating magnetic hard disk drive, an optical disk drive, or a flash-based storage drive, or other such solid-state, magnetic, or optical storage device.

Further, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Operations as described herein may be performed on or via a website. The website may operate on a server computer or locally (e.g., by downloading to a client computer, or via a server farm). The website may be accessed via a mobile phone or PDA, or on any other client. The web site may use HTML program code in any form (e.g., MHTML or XML) and via any form such as cascading style forms ("CSS") or others.

Furthermore, the claims of the present inventors that are intended to use only the word "means for …" are to be interpreted according to 35usc 112, paragraph six. Furthermore, any limitations from the specification are not intended to be added to any claims unless they are expressly included in the claims. The computer described herein may be any kind of computer, a general purpose processor or a specific purpose computer (such as a workstation). The program may be written in C or Java, brew, or any other programming language. The program may reside on a storage medium (e.g., magnetic or optical), such as a computer hard drive, removable disk or media (such as a memory stick or SD media), or other removable media. The program may also be run via a network (e.g., where a server or other machine sends signals to the local machine), which may allow the local machine to perform the operations described herein.

It should also be noted that all features, components, functions, acts, and steps described with respect to any embodiment provided herein are intended to be freely combinable with and replaceable with those from any other embodiment. If a particular feature, component, element, function, or step is described in connection with only one embodiment, it should be understood that the feature, component, element, function, or step can be used with every other embodiment described herein unless expressly stated otherwise. Thus, this section is intended to serve as a antecedent basis and written support for introducing claims at any time that combining features, elements, components, functions, and acts or steps from different embodiments or substituting features, elements, components, functions, and acts or steps from one embodiment with those of another embodiment, such combination or substitution being possible in a particular instance even if the following description does not explicitly recite. It is expressly recognized that the explicit recitation of each and every possible combination and substitution is overly cumbersome, particularly in view of the permissibility of each such combination and substitution, as will be readily recognized by the ordinarily skilled artisan.

In some examples, an entity is described herein as being coupled to other entities. It should be understood that the terms "interwork," "coupled," or "connected" (or any of these forms) are used interchangeably herein and are generic to both direct coupling of two entities (without any non-negligible (e.g., parasitic) intervening entities) and indirect coupling of two entities (with one or more non-negligible intervening entities). Where entities are shown as directly coupled together or described as coupled together without any intervening descriptions of entities, it should be understood that entities may also be indirectly coupled together unless the context clearly dictates otherwise.

References to a single item include the possibility that there are several identical items. More specifically, as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. In other words, the use of the article allows for the above description as well as the following "at least one" of the subject matter of the invention claims.

It should be further noted that the scope of the invention may be drafted to exclude any optional element (e.g., "typical", use "can or make", etc., by the elements so specified in the description herein). Accordingly, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "only" and the like, or use of other uses of "negative" claim limitation language, in connection with recitation of claim elements. Without the use of such exclusive terminology, the term "comprising" in the claims shall be taken to include any additional element, irrespective of whether a given number of elements are enumerated in the claims, or the addition of a feature may be regarded as transforming the nature of the element set forth in the claims. However, it is contemplated that any such "comprising" term in the claims may be modified to an exclusive type of "constituent" language. Moreover, unless specifically defined herein, all technical and scientific terms used herein should be given the broadest possible meaning commonly understood by one of ordinary skill in the art while maintaining the validity of the claims.

While the embodiments are susceptible to various modifications and alternative forms, specific examples thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that these embodiments are not intended to be limited to the particular forms disclosed, but, on the contrary, these embodiments are to cover all modifications, equivalents, and alternatives falling within the spirit of the invention. Furthermore, any features, functions, acts, steps or components of the embodiments, as well as negative limitations (as referenced above, or otherwise) in the scope of the invention by which the claimed invention is not defined by features, functions, steps or components, may be recited in, or added to, the claimed invention. Accordingly, the breadth of a variation of the present invention or of an embodiment of the present invention is not limited by the examples provided, but is limited only by the scope of the following claim language.

Claims

1. A system for characterizing a sample using second harmonic generation, comprising:

a sample support configured to support a sample;

An optical detection system comprising at least one optical detector configured to receive the plurality of SHG signals emitted from the sample and to generate a detected SHG signal;

receiving at least one detected SHG signal; and

2. The system of claim 1, wherein the geometric feature of the sample is determined based at least in part on an image of the plurality of detected SHG signals and geometric features of one or more structures on the sample that are completed or not completed.

3. The system of claim 1, wherein the one or more hardware processors receive the at least one detected SHG signal after performing a first manufacturing step on the sample.

4. The system of claim 3, wherein the system is included in-line in a manufacturing system.

5. The system of claim 4, wherein the first manufacturing step is a step in a manufacturing process performed by the manufacturing system.

6. The system of claim 1, wherein the one or more hardware processors are configured to:

identifying an unplanned variation in a geometric feature of the sample; and

Outputting an indication of the unplanned variation.

7. The system of claim 6, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool in the manufacturing system to adjust the unplanned variation in the sample.

8. The system of claim 7, wherein the one or more hardware processors are configured to output the indication of the unplanned variation to a sample processing tool for performing a second manufacturing step on the sample after the first manufacturing step to adjust for the unplanned variation in the sample.

9. The system of claim 6, wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a user through a user interface of the system.

10. The system of claim 1, wherein the geometric feature comprises a size of one or more devices or one or more portions of devices that have completed or have not completed.

11. The system of claim 1, wherein the geometric feature comprises a critical dimension of one or more devices or portions of one or more devices that have completed or have not completed.

12. The system of claim 1, wherein the geometric feature comprises a shape of one or more devices or portions of one or more devices that have completed or have not completed.

13. The system of claim 1, wherein the geometric feature comprises a lateral dimension including a width or a length of one or more devices or portions of one or more devices that have completed or have not completed.

14. The system of claim 1, wherein the geometric feature comprises a height of one or more devices or portions of one or more devices that have completed or have not completed.

15. The system of claim 1, wherein the geometric feature comprises a lateral spacing between devices or portions of devices that are completed or have not been completed.

16. The system of claim 1, wherein the geometric feature comprises an inclination or slope of one or more devices or portions of one or more devices that have completed or have not completed.

17. The system of claim 1, wherein the geometric feature comprises a sidewall slope or a slope of one or more devices or portions of one or more devices that have completed or have not completed.

18. The system of claim 1, wherein the one or more hardware processors are configured to determine a geometric feature of the sample based on the at least one detected SHG signal.

19. The system of claim 1, wherein the one or more hardware processors are configured to determine a change in a geometric characteristic of the sample based on the at least one detected SHG signal.