CN115290571A

CN115290571A - Measuring apparatus and measuring method

Info

Publication number: CN115290571A
Application number: CN202210983935.0A
Authority: CN
Inventors: 张雪娜; 洪峰
Original assignee: Shenzhen Aisin Semiconductor Technology Co ltd
Current assignee: Shenzhen Aisin Semiconductor Technology Co ltd
Priority date: 2022-08-16
Filing date: 2022-08-16
Publication date: 2022-11-04

Abstract

A measuring apparatus and a measuring method are disclosed. According to an embodiment, a measurement device may include: a first optical measurement system configured to irradiate a target area of a measurement object with first light and detect a first signal generated in response to the first light by the target area of the measurement object; a second optical measurement system as a raman scattering measurement system configured to irradiate second light to a target region of a measurement object and detect a second signal including raman scattered light generated in response to the second light by the target region of the measurement object; and an analysis device configured to determine a first characteristic of a target region of the measurement object from the first signal, and determine a second characteristic of the target region of the measurement object from the second signal and the first characteristic.

Description

Measuring apparatus and measuring method

Technical Field

The present disclosure relates to optical measurement techniques, and more particularly, to measurement devices and measurement methods that combine raman scattering measurements with other optical measurements, such as ellipsometry and/or reflectance measurements.

Background

Various techniques exist for optically measuring a sample, such as raman spectroscopy, ellipsometry, reflectometry, and the like.

Raman spectroscopy relies on the inelastic scattering of photons. The vibrational modes of the material being detected absorb or enhance the incident photon energy, resulting in a shift in the wavelength of the scattered light. Raman spectroscopy provides direct information about these vibrational characteristics, and the raman spectra of each chemical component are unique and therefore can be referred to as fingerprint information for molecules. In the field of semiconductor measurement, raman spectroscopy can be used to measure, for example, crystallinity, crystalline phase, composition, stress/strain, and the like.

The ellipsometer is an instrument for performing nondestructive measurement on a thin film by using an ellipsometry technology, and the refractive index and the thickness of the optical thin film are determined by using the reflection of polarized light on the upper surface and the lower surface of the thin film and obtaining the relation between optical parameters and a polarization state through a Fresnel formula.

The reflectometer is an instrument for performing nondestructive measurement on a thin film by reflection, and the refractive index and the thickness of the optical thin film are determined by utilizing the reflection of polarized light or non-polarized light on the upper surface and the lower surface of the thin film and obtaining the relation between optical parameters and light intensity through a Fresnel formula.

With only a single measurement technique, there is a problem that it may be difficult to accurately measure.

Disclosure of Invention

It is an object of the present disclosure, at least in part, to provide a measurement apparatus and measurement method that combines raman scattering measurements with other optical measurements, such as ellipsometry and/or reflectance measurements.

According to an aspect of the present disclosure, there is provided a measuring apparatus including: a first optical measurement system configured to irradiate first light to a target area of a measurement object and detect a first signal generated in response to the first light by the target area of the measurement object; a second optical measurement system as a raman scattering measurement system configured to irradiate second light to a target region of a measurement object and detect a second signal including raman scattered light generated in response to the second light by the target region of the measurement object; and an analysis device configured to determine a first characteristic of a target region of the measurement object from the first signal, and determine a second characteristic of the target region of the measurement object from the second signal and the first characteristic.

According to another aspect of the present disclosure, there is provided a measurement method including: irradiating first light to a target area of a measurement object by a first optical measurement system, and detecting a first signal generated in response to the first light by the target area of the measurement object; irradiating a second light to a target region of the measurement object by a second optical measurement system as a raman scattering measurement system, and detecting a second signal including raman scattered light generated in response to the second light by the target region of the measurement object; determining a first characteristic of a target region of the measurement object from the first signal; and determining a second characteristic of the target region of the measurement object based on the second signal and the first characteristic.

According to embodiments of the present disclosure, different optical measurement systems may be enhanced with respect to each other, e.g. a measurement of a first optical measurement system may be used to enhance a measurement of a second optical measurement system.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

FIG. 1 schematically shows a block diagram of a measurement device according to an embodiment of the disclosure;

FIG. 2 schematically shows a block diagram of a measurement device according to an embodiment of the disclosure;

FIG. 3 schematically shows a block diagram of a measurement device according to another embodiment of the disclosure;

FIG. 4 schematically shows a block diagram of a measurement device according to another embodiment of the present disclosure;

FIG. 5 schematically shows a block diagram of a measurement device according to another embodiment of the present disclosure;

FIG. 6 schematically illustrates a block diagram of a common light source according to an embodiment of the present disclosure;

7 (a), 7 (b), and 7 (c) schematically illustrate partial block diagrams of a reflectance measurement system according to an embodiment of the present disclosure;

FIGS. 8 (a) and 8 (b) schematically illustrate partial block diagrams of an ellipsometry system according to an embodiment of the present disclosure;

FIG. 9 schematically shows a flow chart of a measurement method according to an embodiment of the present disclosure;

FIG. 10 schematically illustrates a flow chart for determining a first characteristic in accordance with an embodiment of the present disclosure;

fig. 11 schematically illustrates a specific example of determining a first characteristic according to an embodiment of the present disclosure;

FIG. 12 schematically illustrates a flow chart for determining a second characteristic according to an embodiment of the disclosure;

fig. 13 schematically shows a specific example of determining the second characteristic according to an embodiment of the present disclosure.

Throughout the drawings, the same or similar reference numerals denote the same or similar components.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. Various schematic diagrams in accordance with embodiments of the present disclosure are shown in the figures. The figures are not drawn to scale, wherein certain details are exaggerated and some details may be omitted for clarity of presentation. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The words "a", "an" and "the" and the like as used herein are also intended to include the meanings of "a plurality" and "the" unless the context clearly dictates otherwise. Furthermore, the terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.

Fig. 1 schematically shows a block diagram of a measurement device according to an embodiment of the disclosure.

As shown in fig. 1, the measurement apparatus 100 according to the embodiment may include a first optical measurement system 110, a second optical measurement system 130, an analysis device 150, and a control device 170.

The first optical measurement system 110 may be a system that measures a measurement object, such as a film or a stack of films formed on a substrate in a semiconductor manufacturing process, based on one or more optical measurement techniques (other than the raman scattering measurement technique described below), such as an ellipsometry technique or a reflectometry technique. As shown by a dotted arrow in the figure, the first optical measurement system 110 may irradiate light (hereinafter, referred to as "first light" for convenience) to a target region of a measurement object, and detect an optical signal (hereinafter, referred to as "first signal" for convenience) such as a reflected optical signal, generated by the target region of the measurement object in response to the irradiation of the first light. The first light may be polarized (e.g., elliptically polarized in the case of an ellipsometry technique, or linearly polarized in the case of a reflectance measurement technique) or unpolarized (e.g., in the case of a reflectance measurement technique). Polarized light may be generated by a polarizer, as described in further detail below. The first light is subjected to optical processes such as emission, refraction, multi-beam interference, and the like on the surface of the target region, and the outgoing light carrying the optical constant (for example, refractive index) and the structural information (for example, thickness) of the target region can be obtained as the first signal. By analyzing the first signal, e.g. its light intensity, polarization state change, etc., relevant properties of the target area (hereinafter referred to as "first properties" for convenience), e.g. refractive index and/or film thickness, can be determined.

The second optical measurement system 130 may be a raman scattering measurement system. Similarly, as indicated by a dotted arrow in the figure, the second optical measurement system 130 as a raman scattering measurement system may irradiate light (hereinafter, referred to as "second light" for convenience) to a target region of a measurement object, and detect an optical signal (hereinafter, referred to as "second signal" for convenience) including raman scattered light generated by the target region of the measurement object in response to the irradiation of the second light. By analyzing the second signal, such as the peak position, intensity, peak width, etc., of the raman spectrum, a relevant characteristic (hereinafter referred to as "second characteristic" for convenience) of the target region, such as at least one of film thickness, strain/stress, deformation, defect, crystallinity, composition, etc., can be determined.

The analyzing device 150 may analyze the first signal obtained by the first optical measurement system 110 and the second signal obtained by the second optical measurement system 130 to determine a correlation characteristic, such as the first characteristic and the second characteristic described above. According to embodiments of the present disclosure, different measurement techniques may be enhanced with each other. For example, the analyzing means 150 may utilize the first characteristic determined by analyzing the first signal when determining the second characteristic by analyzing the second signal to enhance the determination of the second characteristic. This will be described in further detail below.

The control device 170 may control the overall operation of the measuring apparatus 100. For example, the control device 170 may control the movement of a sample stage (not shown) so that a target region of a measurement object placed on the sample stage can be moved to an irradiation region (e.g., a focal point) of the first and second

optical measurement systems

110 and 130. According to an embodiment of the present disclosure, in order that the respective measurement results of the first optical measurement system 110 and the second optical measurement system 130 may be enhanced to each other, the first light from the first optical measurement system 110 and the second light from the second optical measurement system 130 may be irradiated onto the same or substantially the same target region of the measurement object. As another example, the control device 170 can control moving optical components (e.g., polarizers, compensators, analyzers, etc., described below) in the first optical measurement system 110 and the second optical measurement system 130 to achieve incidence/detection of light of different polarization states. As another example, the control device 170 may control the analysis device 150 to efficiently organize the analysis of the measurement results.

The control device 170 may include a processor or microprocessor, a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a single chip, etc. The control device 170 may be implemented as a general purpose or special purpose computer. The general purpose or special purpose computer may execute the program instructions to perform the various operations described in this disclosure. Such program instructions may be stored in a local memory or downloaded from a remote memory via a wired or wireless connection. Alternatively, the operations described in the present disclosure may be performed by the control apparatus 170 requesting a remote server, or some of the operations may be performed by the control apparatus 170 and other operations may be performed by other controllers or servers networked with the control apparatus 170.

In this example, a separate analysis device 150 and control device 170 are shown. However, the present disclosure is not limited thereto. For example, the analysis apparatus 150 and the control apparatus 170 may be jointly implemented by one or more computing platforms, a portion of the computing resources of which may implement the analysis apparatus 150, and another portion of the computing resources may implement the control apparatus 170.

FIG. 2 schematically shows a block diagram of a measurement device according to an embodiment of the disclosure.

As shown in fig. 2, the measuring apparatus according to this embodiment may include a light source section 290a, a first optical measuring system 110a, and a second optical measuring system 130.

The light source section 290a may include a light source that emits light and optical components for guiding the light emitted from the light source into the first optical measurement system 110a and the second optical measurement system 130, respectively.

The light source may include one or more lasers emitting a particular wavelength. In FIG. 2, four lasers 290-1, 290-3, 290-4, respectively emitting different wavelengths (e.g., 375nm, 445nm, 488nm, 532 nm), are schematically illustrated. However, the present disclosure is not limited thereto, and more or fewer lasers may be provided according to the needs of the application (e.g., characteristics of the measurement object), or one or several of the lasers may be selectively turned on in the case where a plurality of lasers are provided (e.g., under the control of the control device 170). In addition, when the measurement object is changed, the laser to be turned on may also be switched. Light from different lasers may be simultaneously irradiated onto the same target area of the measurement object in order to obtain measurement signals at different wavelengths.

Light from different lasers 290-1, 290-3, 290-4 may be combined into the same beam of light ("incident light") by mirrors M1, M2, M3, M4. Mirror M1 may reflect light from laser 290-1 (at least partially); mirror M2 may reflect light (at least partially) from laser 290-2 and transmit light (at least partially) from mirror M1; mirror M3 may reflect light (at least partially) from laser 290-3 and transmit light (at least partially) from mirrors M1, M2; mirror M4 may reflect (at least partially) light from laser 290-4 and transmit (at least partially) light from mirrors M1, M2, M3. The mirrors M1, M2, M3, M4 may be configured to selectively reflect (a band of) the light of the respective lasers 290-1, 290-3, 290-4, e.g. mirrors that are aluminized, gold plated, nickel plated, etc. The lasers 290-1, 290-3, 290-4 may emit light in the same or substantially the same direction and the reflective surfaces of the respective reflectors M1, M2, M3, M4 may be positioned parallel or substantially parallel so that the resulting incident light may be in the form of parallel or substantially parallel light. The emission intensity of the lasers 290-1, 290-3, 290-4 can be controlled in combination with the reflection and transmission properties of the respective reflectors M1, M2, M3, M4 so that the respective component lights in the incident light have the same or substantially the same intensity, which can facilitate subsequent analysis and calculation.

The incident light can be split into different fractions by a beam splitter BS 1: a part (hereinafter, referred to as "first incident light" for convenience) is guided into the first optical measurement system 110a, and another part (hereinafter, referred to as "second incident light" for convenience) is guided into the second optical measurement system 130. For example, the beam splitter BS1 may be a beam splitter that transmits a part of the incident light on the one hand to enter the first optical measurement system 110 a; and on the other hand reflects a portion of the incident light to enter the second optical measurement system 130. The beam splitter BS1 may have the same or substantially the same reflection and transmission characteristics for each component light of the incident light, so that the intensity of the component light of the incident light entering each optical measurement system may be kept substantially the same (e.g. no particular attenuation or particular enhancement of a component light occurs) between the component light of the incident light, but the intensity of the incident light of different systems may be outside the difference (depending on the transmission reflectance or splitting ratio of the beam splitter BS1, e.g. 1: 1, 3: 7, 2: 8, 1: 9, etc.). In addition, other light diverting components, such as a mirror M5, may also be included to accommodate the optical path in each optical measurement system. Mirror M5 may have broad spectral reflection characteristics, such as a flat or substantially flat reflectivity in the wavelength band of about 200nm to about 2000 nm. Similarly, the mirror M5 may be a mirror plated with aluminum, gold, nickel, or the like.

The first optical measurement system 110a is illustrated herein as an ellipsometry measurement system.

It is desirable to use polarized light in the ellipsometry system, so the optical path thereof may include a polarization generation arm for generating a polarization conversion function for converting the first incident light (passing through the beam splitter BS1 and the mirror M5) entering the first optical measurement system 110a into elliptically polarized light. For example, the polarization generating arm may include a polarizer PL1 and a compensator R1. Polarizer PL1 may be a polarizing plate to convert incident light into linearly polarized light. The compensator R1 may generate a phase delay (e.g., about 90 ° or 127 °) such as a 1/4 wave plate (between o-light and e-light) to convert linearly polarized light into elliptically polarized light. In addition, the polarization generating arm may further include other optical components, such as an aperture A2 for suppressing stray light and limiting, and a lens L3 for focusing the generated elliptically polarized light onto the target area of the measurement object S.

The elliptically polarized light is incident on a target region of the measurement object S, and reflection, refraction, and multi-beam interference processes occur on the (front and rear) surfaces of the target region, and the dielectric surface action causes changes in the polarization state (for example, phase difference Δ, amplitude ratio ψ).

The polarization state of the reflected light reflected from the target region may be detected so as to obtain a change in the polarization state with respect to the incident light, and thus extract the characteristics (e.g., film thickness, refractive index) of the target region of the measurement object S. A polarization detection arm may be included to detect the reflected light (with its polarization state changed). For example, the polarization detection arm may have the same structure as the polarization generation arm, e.g. including an analyzer PL2 and a compensator R2. Similarly, the polarization detection arm may also include other optical components, such as a lens L4 to convert reflected light from the target area into parallel light, an aperture A3 to suppress stray light and limit it.

The optical signal detected by the polarization detection arm, i.e., the first signal, can be sent to the optical detector 300-2. In this embodiment, the incident light is laser light of one or more specific wavelengths, and the light detector 300-2 may be a photodiode that detects light intensity.

Both compensators R1 and R2 can rotate. For example, compensators R1 and R2 may each be rotated to one or more particular angles (and thus different combinations of angles may be achieved). Alternatively, compensators R1 and R2 may rotate at a speed and the rotational speed of the two may have a constant ratio, e.g., 5: 1, 4: 3, 5: 3, etc. Such a dual rotation compensator configuration may enable measurement of more information of the target area, for example, a4 × 4-order mueller matrix may be obtained.

The second optical measurement system 130 may be a raman scattering measurement system.

The raman scattering measurement system may include an excitation light path that irradiates incident light to excite a raman effect to a target region of a test object and a collection light path that collects raman scattered light generated by the target region in response to the incident light. To make the measuring device more compact, the excitation and collection optical paths may be integrated in the same lens. For example, a beam splitter BS2 may be provided. The beam splitter BS2 may on the one hand (at least partially) reflect the second incident light from the light source 290a (more specifically, the beam splitter BS 1) to illuminate the target area (in a direction, e.g., perpendicular or substantially perpendicular, to the target area) and on the other hand (at least partially) transmit raman scattered light from the target area. For example, beam splitter BS2 can be a beam splitter having a certain transmission to reflection ratio or splitting ratio (e.g., 1: 1, 3: 7, 2: 8, 1: 9, etc.). Optionally, the beam splitter BS2 may also transmit a portion of the second incident light for light intensity monitoring.

In the excitation light path, a half-wave plate HWP1 may be provided. The half-wave plate HWP1 may be rotated so that the polarization direction of the second incident light may be rotated to accommodate different patterns of target areas. A neutral density patch D1 may also be provided in the excitation light path to achieve attenuation of the intensity of the second incident light (the attenuation may be uniform or substantially uniform for different component lights). In addition, a filter F1 may be disposed in the excitation light path to filter the second incident light, so as to improve the purity of the second incident light. For example, the filter F1 may be a MaxLine filter that transmits only laser lines.

A lens L1 may be provided to focus incident light onto the target area and may convert (divergent) light from the target area, including raman scattered light, into parallel light or substantially parallel light for transmission through the beam splitter BS2 to be detected.

In the collection path, a filter F2 may be provided to filter the optical signal from the target area. The filter F2 may be an edge filter or a long pass filter that filters out laser lines and optical signals having wavelengths shorter than the laser lines (e.g., optical signals due to other effects), while passing raman scattered light having wavelengths longer than the laser lines. In addition, other optical components, such as a mirror M6 for changing the direction of the optical path to achieve a compact structure, a lens L2 for converging the raman scattered light to be introduced into the optical detector 300-1, and an aperture A2 for suppressing the stray light and limiting the position, may also be disposed in the collection optical path. Mirror M6 may have broad spectral reflectance characteristics, such as a flat or substantially flat reflectance in the wavelength band from about 200nm to about 2000 nm. The mirror M6 may be a mirror plated with aluminum, gold, nickel, or the like.

The light detector 300-1 may be a spectrometer to obtain a raman scattering spectrum. For example, a spectrometer may measure raman spectra by splitting photons of different energies by grating diffraction and then imaging on a CCD.

According to an embodiment, the filters F1, F2 may be filter wheels. Each filter wheel may be fitted with a set of filters having different filter characteristics and may be rotated so that different filters are placed in the optical path to suit different needs.

In the above embodiment, the incident light entering the first optical measurement system 110a and the second optical measurement system 130 is split by the common light sources 290-1, 290-3, 290-4. However, the present disclosure is not limited thereto. In particular, the first optical measuring system and the second optical measuring system may be provided with separate light sources, taking into account that they may have different requirements for the incident light.

Fig. 3 schematically shows a block diagram of a measurement device according to another embodiment of the present disclosure.

The embodiment shown in fig. 3 is substantially the same as the embodiment shown in fig. 2, except for the light source section 290 b. Therefore, the light source section 290b will be mainly described below, and other components may refer to the description above in conjunction with fig. 2.

In the light source section 290b, similarly to the light source section 290a described above, laser light sources (lasers 290-1, 290-3, 290-4) may be provided as light sources of the second optical measurement system 130, for example, introduced into the second optical measurement system 130 through a mirror M7. In addition, for the first optical measurement system 110a, a light source 290-5, for example, a broad spectrum light source such as one or more of a Laser Driven Light Source (LDLS), a deuterium lamp, a xenon lamp, or the like, may be additionally provided. Alternatively, the light source 290-5 may also be a laser light source, but may have different characteristics than the laser light source of the second optical measurement system 130, such as a laser line having a different wavelength.

In the case where the light source 290-5 is a broad spectrum light source, the light detector 300-2 may be a spectrometer.

In the above embodiment, the first optical measurement system 110a is an ellipsometry system. However, the present disclosure is not limited thereto. For example, the first optical measurement system may also be a reflection measurement system.

Fig. 4 schematically shows a block diagram of a measurement device according to another embodiment of the present disclosure.

In the embodiment shown in fig. 4, the light source 290a and the second optical measurement system 130 may be referred to the description above in conjunction with fig. 2. Here, the first optical measurement system 110b as a reflection measurement system is mainly described.

In a reflection measurement system, polarized light may also be used, and thus the optical path thereof may similarly include a polarization generating arm for converting the first incident light entering the first optical measurement system 110b into linearly polarized light. For example, the polarization generating arm may comprise a polarizer PL3. Similarly, the polarization-generating arm may also include other optical components, such as an aperture A4 to suppress stray light and to limit it.

In this embodiment, the generated linearly polarized light is focused onto a target area of the measurement object S with the off-axis parabolic mirror OAP 1. Of course, the present disclosure is not limited thereto. For example, as shown in fig. 2, by adjusting the angle of the mirror M5, the incident light can be made incident at an oblique angle with respect to the target area. In this case, the lens L3 can be similarly employed to achieve focusing.

The linearly polarized light is incident on a target region of the measurement object S, and the processes of reflection, refraction, and multi-beam interference occur on the (front and rear) surfaces of the target region, so that reflected light of a certain intensity is obtained.

The light intensity of the reflected light reflected from the target region can be detected, and the characteristics (e.g., film thickness, refractive index) of the target region of the measurement object S can be extracted therefrom. A polarization detection arm may be included to detect the reflected light. For example, the polarization detection arm may have the same structure as the polarization generation arm, e.g. including the analyzer PL4. Similarly, the polarization detection arm may also include other optical components, such as an aperture A5 to suppress stray light and limit it.

Corresponding to the off-axis parabolic mirror OAP1, an off-axis parabolic mirror OAP2 may be employed to convert (at least a part of) the reflected light from the target area into parallel light for introduction into the polarization detection arm.

The optical signal detected by the polarization detection arm, i.e., the first signal, can be sent to the optical detector 300-3. In this embodiment, the incident light is one or more lasers of a particular wavelength, and the light detector 300-3 may be a photodiode that detects the intensity of the light.

Similarly, in the case of a reflection measurement system, a separate light source may also be provided.

Fig. 5 schematically shows a block diagram of a measurement device according to another embodiment of the present disclosure.

The embodiment shown in fig. 5 is substantially the same as the embodiment shown in fig. 4, except for the light source section 290 b. As for the light source section 290b, the description above in conjunction with fig. 3 can be referred to.

In the above-described embodiment, an example in which two measurement systems use a common light source through the beam splitter BS1 is described. However, the present disclosure is not limited thereto. For example, the measurement apparatus according to an embodiment may include more measurement systems, such as an ellipsometry system, a reflection measurement system, and a raman scattering measurement system. Even in this case, a common light source may be provided.

Fig. 6 schematically shows a block diagram of a common light source according to an embodiment of the present disclosure.

As shown in FIG. 6, incident light from a light source (e.g., the lasers 290-1, 290-3, 290-4 described above) may be incident on the beam splitter BS1, and the beam splitter BS1 may reflect a portion of the incident light for guidance into the Raman scattering optical measurement system 130. In addition, the incident light transmitted through the beam splitter BS1 may be incident on another beam splitter BS3, and the beam splitter BS3 may reflect a part of the incident light to be guided into the reflection measurement system 110b. In addition, the incident light transmitted through the beam splitter BS2 may be incident on the reflector M5 to be guided into the ellipsometry system 110 a. The beam splitters BS1 and BS2 may have suitable splitting ratios to distribute the incident light intensity between the different systems.

Of course, in the case where the measuring apparatus is provided with three or even more measuring systems, it is not limited that all of the three or more measuring systems use a common light source. For example, some of the measurement systems may use a common light source (e.g., the reflectance measurement system and the ellipsometry system may use a common broad spectrum light source), while one or more other measurement systems may each use a separate light source (e.g., the raman scattering measurement system may use a laser light source). When a common light source is used, a beam splitter in combination with a mirror configuration, such as shown in fig. 6, may be used.

Hereinafter, different configurations of the first optical measurement system will be described in further detail.

Fig. 7 (a), 7 (b) and 7 (c) schematically illustrate partial block diagrams of a reflection measurement system according to an embodiment of the present disclosure.

The configuration of the reflection measurement system shown in fig. 7 (a) is the same as that described above in connection with fig. 4 and 5, and here mainly shows the rotational configuration of the polarizer PL3 and the analyzer PL4. The polarized light passing through the polarizer PL3 may be incident on a target region of the measurement object S. The analyzer PL4 may be rotated to one or more specific angles or continuously rotated at a certain speed. In addition, polarizer PL3 may be stationary or may be rotated, for example, to one or more specified angles or continuously rotated at a certain speed.

In the reflection measurement system shown in fig. 7 (b), compared with the reflection measurement system shown in fig. 7 (a), two mirrors are added to the incident light path and the outgoing light path, respectively: mirrors M8 and M10 having reflecting surfaces facing in parallel are inserted in the incident light path, and mirrors M9 and M11 having reflecting surfaces facing in parallel are inserted in the outgoing light path. Due to this insertion of the mirror, stray light can be suppressed compared to the reflection measurement system shown in fig. 7 (a), because stray light can be at least partially reflected out of the optical path of the system by two reflections.

In addition, the mirror M8 and the mirror M9 may be driven by a motor to be relatively moved with respect to the measurement object S. Accordingly, as shown by a dotted line box in the figure, the off-axis parabolic mirror OAP1 may be motor-driven to move together with the mirror M8, and the off-axis parabolic mirror OAP2 may be motor-driven to move together with the mirror M9, so as to maintain the optical path alignment. Due to this movement, the incident light can be incident on the target area of the measurement object S at different incident angles.

In the reflectometry system shown in fig. 7 (b), the off-axis parabolic mirrors OAP1 and OAP2 also move, easily causing drift misalignment of the optical path. As shown in fig. 7 (c), fixed off-axis parabolic mirrors OAP1 'and OAP2' may be provided. In addition, to accommodate the movement of mirrors M8 and M9, the reflective surfaces of off-axis parabolic mirrors OAP1 'and OAP2' may be relatively large. In this case, the reflecting surfaces of the off-axis parabolic mirrors OAP1 'and OAP2' may be disposed opposite to each other, instead of facing away from each other as shown in fig. 7 (b), so as not to influence the traveling of the incident light and the reflected light by the large off-axis parabolic mirrors OAP1 'and OAP2' themselves. Accordingly, the reflection surfaces of the mirrors M8 and M10 may be disposed to vertically oppose each other, and the reflection surfaces of the mirrors M9 and M10 may be disposed to vertically oppose each other. Since the off-axis parabolic mirrors OAP1 'and OAP2' are fixed, the optical path stability can be ensured.

The solution of achieving the change of the incident angle by means of the off-axis parabolic mirror in combination with the mirror as described above in connection with fig. 7 (b) and 7 (c) can also be applied in an ellipsometry system.

Fig. 8 (a) and 8 (b) schematically illustrate partial block diagrams of an ellipsometry system according to an embodiment of the present disclosure.

The ellipsometry system shown in fig. 8 (a) has an off-axis parabolic mirror and two mirrors added in the incident and outgoing light paths, respectively, compared to the ellipsometry system in the previous embodiment: the off-axis parabolic mirror OAP1 and the mirrors M8 and M10 whose reflecting surfaces are parallel to each other are inserted in the incident light path, and the off-axis parabolic mirror OAP2 and the mirrors M9 and M11 whose reflecting surfaces are parallel to each other are inserted in the outgoing light path. For these off-axis parabolic mirrors and reflectors, see the description above in connection with fig. 7 (b).

The ellipsometry system shown in fig. 8 (b) employs the combination of off-axis parabolic mirrors OAP1 'and OAP2' plus mirrors M8 to M11 described above in connection with fig. 7 (c), with the other configuration being the same as that of fig. 8 (a).

Fig. 9 schematically shows a flow chart of a measurement method according to an embodiment of the present disclosure.

The measurement method 100 according to the embodiment may include measuring a first signal by a first optical measurement system and measuring a second signal by a second optical measurement system in

operations

901 and 903, respectively. For example, the first optical measurement system may be the ellipsometry system 110a and/or the reflectance measurement system 110b described above, and the second optical measurement system may be the raman scattering measurement system 130 described above. The first optical measurement system may irradiate a first light onto a target area of a measurement object and detect a reflected light. In addition, the second optical measurement system may irradiate a second light onto the same target region of the measurement object and detect the raman scattered light.

Operations

901 and 903 may be performed in parallel.

In operation 905, a first characteristic of a target region of a measurement object may be determined according to the first signal. In the case of the ellipsometry system 110a and/or the reflectance measurement system 110b, the first characteristic may include a refractive index and/or a thickness of the film layer. This will be described in further detail below.

In operation 907, a second characteristic of the target area of the measurement object may be determined from the second signal and additionally from the first characteristic determined in operation 905. In contrast to conventional raman scatterometry systems, the first property determined by the first optical measurement system is additionally taken into account when analyzing the raman spectrum to enhance the raman analysis, even if certain properties of the conventional raman scatterometry system can only be qualitatively analyzed. This will be described in further detail below.

Fig. 10 schematically shows a flow chart of determining a first characteristic according to an embodiment of the present disclosure.

The (target area of the) measurement object S may be described by a model comprising a layered structure simulating the (target area of the) measurement object S, comprising the substrate and the material layer formed thereon. Each layer in the stack may be described by model data such as thickness (d) and optical constants (n, k). Initial set values can be given to first characteristics (for example, film thickness d, refractive index n, k, and the like) to be measured. At operation 1031, for the model described by the model data, the response of the model under the same condition of being irradiated by the first light may be simulated to obtain simulated data (which may also be regarded as a first signal expected to be obtained if the model with the current model data is measured by the first optical measurement system). At operation 1033, the simulation data (expected first signal) may be compared to the actual measured first signal. If it is determined in operation 1035 that the simulation data does not match the measured first signal, then in operation 1039, the associated set point in the model data may be adjusted, and

operations

1031 and 1033 may be repeated. On the other hand, if it is determined at operation 1035 that the simulation data matches the measured first signal, a set value for the first characteristic employed by the current model data may be output as the measured value of the first characteristic.

Fig. 11 schematically shows a specific example of determining the first characteristic according to an embodiment of the present disclosure.

As shown in fig. 11, the measurement object S can be described by using a stack model of N layers (N is a natural number of 1 or more). Each layer in the model has corresponding model data such as (n) ₁ ，k ₁ ，d ₁ )、(n ₂ ，k ₂ ，d ₂ )、…、(n _i ，k _i ，d _i )、…、(n _N ，k _N ，d _N ) (1. Ltoreq. I. Ltoreq.N), where d _i Denotes the film thickness of the i-th layer, n _i 、k _i Denotes the refractive index of the i-th layer (complex refractive index n) _i +ik _i ). Other characteristics, such as roughness, uniformity, etc., may also be included in the model data. Model parameters such as n _i 、k _i May be wavelength dependent. The dependence of the refractive index on the wavelength over a certain wavelength band is schematically shown in the upper right of the stack model in fig. 11. The initial setting values of the model and the model data may be determined based on design data of the measurement object S.

The response of the model to the first light under the same measurement conditions may be simulated based on the measurement conditions (e.g., spectrum, polarization state, angle of incidence, etc.) of the first optical measurement system at the time the measurement was taken.

To facilitate comparison of the simulation result with the first signal actually measured by the first optical measurement system, both may take the same representation, for example a mueller matrix. Specifically, in simulation, the mueller matrix may be simulated and calculated based on the model; on the other hand, the first signal (typically, light intensity or spectrum signal) actually measured by the first optical measurement system may be transformed into a mueller matrix. For example, the first signal may be fourier transformed to obtain the intensity components of light at each frequency. For each frequency light intensity component, a Mueller matrix element analytic form may be employed based on system parameters (e.g., angle of incidence, circular frequency, etc.). Of course, the measurement signal is not limited to being represented by a mueller matrix, and other representations, such as normalized coordinate system (n.c.s.) data, may also be used.

In comparing the simulation data to the first signal (e.g., both in the form of a muller matrix), a non-linear fitting algorithm, a genetic algorithm, or the like may be employed. The match between them can be determined according to goodness of fit (GoF).

Fig. 12 schematically shows a flow chart for determining the second characteristic according to an embodiment of the present disclosure.

After determining the measurement of the first characteristic of the target region (matching the first signal of the first optical measurement system with the simulation result of the corresponding model data) as described above, a raman spectrum obtained by the model under the same illumination by the second light may be predicted based on such model data in operation 12071. In operation 12073, the predicted raman spectrum may be compared to an actual measured second signal (i.e., the raman spectrum measured by the second optical measurement system). In operation 12075, a second characteristic of the target area of the measurement object S, such as film thickness, strain/stress, deformation, defect, crystallinity and/or composition, may be determined according to the comparison result. For example, the second characteristic may be determined from a shift between the predicted raman spectrum and the actual measured raman spectrum.

In the upper left corner of fig. 13, a model is shown, which has corresponding model data, in particular wherein the first characteristic has been determined more accurately from measurements of the first optical measurement system. The model can calculate the raman scattering of the second light under the same measurement conditions based on the measurement conditions (e.g., spectrum, polarization state, incident angle, etc.) of the second optical measurement system at the time of measurement. For example, the absorption, reflection, transmission and penetration depths of the raman scattered light in the different layers can be calculated and from this the raman peak associated with the film thickness and composition etc. can be predicted strictly.

The predicted raman spectrum thus obtained (left side of the middle of fig. 13) can be compared with the raman spectrum actually measured by the second optical measurement system (right side of the middle of fig. 13). In the illustrated spectrogram, the abscissa represents the wave number, and the ordinate represents the photon count (light intensity). For example, stress/strain, deformation, pressure, temperature may be determined from the band position shift; crystallinity, defects, doping can be determined in terms of full width at half maximum (FWHM). The second characteristic may be quantitatively determined from an offset between the predicted spectrum and the measured spectrum. The quantitative relationship between the offset and the second characteristic may be determined by machine learning.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the present disclosure, and such alternatives and modifications are intended to be within the scope of the present disclosure.

Claims

1. A measurement device, comprising:

a first optical measurement system configured to irradiate a first light to a target region of a measurement object and detect a first signal generated by the target region of the measurement object in response to the first light;

a second optical measurement system as a raman scattering measurement system configured to irradiate second light to the target region of the measurement object and detect a second signal including raman scattered light generated in response to the second light by the target region of the measurement object; and

an analysis device configured to determine a first characteristic of the target region of the measurement object from the first signal and to determine a second characteristic of the target region of the measurement object from the second signal and the first characteristic.

2. The measurement device of claim 1, wherein the first optical measurement system comprises at least one of an ellipsometry system and a reflectance measurement system.

3. The measurement device of claim 2, wherein the first characteristic comprises a refractive index and/or a thickness of the film layer.

4. The measurement device of claim 2, wherein the ellipsometry system comprises:

a polarization generating arm configured to convert incident light into elliptically polarized light to be irradiated to the target region as the first light; and

a polarization detection arm configured to detect reflected light of the first light reflected by the target area.

5. The measurement device of claim 4,

the polarization-generating arm includes a polarizer and a first compensator,

the polarization detection arm comprises an analyzer and a second compensator.

6. The measurement device of claim 2, wherein the reflectance measurement system comprises:

a polarization generating arm configured to convert incident light into linearly polarized light to be irradiated to the target region as the first light; and

7. The measurement device of claim 6,

the polarization generating arm comprises a polarizer and the polarization detecting arm comprises an analyzer.

8. The measurement apparatus according to any one of claims 4 to 7, wherein the first optical system includes:

a first mirror and a second mirror having reflecting surfaces opposed in parallel to each other, wherein the first mirror is configured to receive the first light from the polarization generating arm, and the second mirror is configured to receive the first light reflected from the first mirror;

a first off-axis parabolic mirror configured to receive the first light reflected from the second mirror and focus the first light to the target area;

a second off-axis parabolic mirror configured to receive reflected light of the first light reflected by the target region and to emit at least a portion of the reflected light in parallel; and

a third mirror and a fourth mirror having reflecting surfaces opposed in parallel to each other, wherein the third mirror is configured to receive the reflected light from the second off-axis parabolic mirror, and the fourth mirror is configured to receive the reflected light reflected from the third mirror and input the reflected light into the polarization detection arm,

wherein the second mirror together with the first off-axis parabolic mirror and the third mirror together with the second off-axis parabolic mirror are configured to be movable relative to the target area to achieve different angles of incidence relative to the target area.

9. The measurement apparatus according to any one of claims 4 to 7, wherein the first optical system includes:

a first mirror and a second mirror having reflecting surfaces vertically opposed to each other, wherein the first mirror is configured to receive the first light from the polarization generating arm, and the second mirror is configured to receive the first light reflected from the first mirror;

a second off-axis parabolic mirror configured to receive reflected light of the first light reflected by the target area and to emit at least a portion of the reflected light in parallel; and

a third mirror and a fourth mirror having reflecting surfaces vertically opposed to each other, wherein the third mirror is configured to receive the reflected light from the second off-axis parabolic mirror, the fourth mirror is configured to receive the reflected light reflected from the third mirror and input the reflected light into the polarization detection arm,

wherein the second mirror and the third mirror are configured to be movable relative to the target area to achieve different angles of incidence relative to the target area.

10. The measurement device of claim 7, further comprising:

a first off-axis parabolic mirror configured to receive the first light from the polarization generating arm and focus the first light to the target area; and

a second off-axis parabolic mirror configured to receive reflected light of the first light reflected by the target area and to emit at least a portion of the reflected light in parallel into the polarization detection arm.

11. The measurement apparatus of claim 1, wherein the second optical measurement system comprises:

a beam splitter configured to receive incident light, to at least partially reflect the incident light to impinge on the target area as the second light in a substantially perpendicular direction relative to the target area, and to at least partially transmit Raman scattered light produced by the target area in response to the second light.

12. The measurement apparatus of claim 11, wherein the second optical measurement system further comprises a half-wave plate and a neutral density plate, wherein the incident light is incident on the beam splitter after passing through the half-wave plate and the neutral density plate.

13. The measurement device of claim 1, further comprising:

a light source configured to generate incident light; and

a beam splitter configured to split the incident light into a first incident light provided to the first optical measurement system and a second incident light provided to the second optical measurement system.

14. The measurement apparatus according to claim 13, wherein the light source includes a plurality of lasers that emit laser light of different wavelengths, the laser light emitted by the plurality of lasers, respectively, being incident on the beam splitter at substantially the same angle to be collectively the incident light.

15. The measurement device of claim 13, wherein the beam splitter is configured to partially transmit the incident light to be provided as the first incident light to the first optical measurement system and partially reflect the incident light to be provided as the second incident light to the second optical measurement system,

wherein the measuring apparatus further comprises: a mirror configured to change a direction of the first incident light.

16. The measurement device of claim 1, further comprising:

a first light source configured to generate first incident light provided to the first optical measurement system; and

a second light source configured to generate a second incident light provided to the second optical measurement system.

17. The measurement device of claim 16, wherein the first light source comprises one or more lasers emitting laser light of a particular wavelength or a broad spectrum light source and the second light source comprises one or more lasers emitting laser light of a particular wavelength.

18. The measurement device of claim 1, wherein the analysis apparatus is configured to obtain the first characteristic of the target region by:

(a) Establishing a model of the target area and simulating simulation data expected to be obtained by the model when measured by the first optical measurement system, wherein the model has associated model data comprising a set value of the first characteristic;

(b) Comparing the first signal to the simulation data;

(c) If the first signal does not match the simulation data, adjusting model data including the set point of the first characteristic, and repeating operations (a) and (b); and

(d) Determining the set value of the first characteristic in the current model data as a measured value of the first characteristic of the target area if the first signal matches the simulation data.

19. The measurement device of claim 18, wherein operation (b) is performed by a non-linear fitting algorithm or a genetic algorithm.

20. The measurement device of claim 18, wherein the first optical measurement system is an ellipsometry system, the simulation data has a representation of a Mueller matrix,

wherein operation (b) comprises:

performing Fourier transform on the first signal measured by the ellipsometry system to obtain a frequency light intensity component;

obtaining the representation of the first signal in a Mueller matrix form according to the frequency light intensity component; and

comparing the Mueller matrix representation of the simulated data to the Mueller matrix representation of the first signal.

21. The measurement device according to claim 1, wherein the analysis means is configured to obtain the second characteristic of the target region by:

predicting a raman spectrum of the target region under the second light irradiation based on the first characteristic of the target region obtained by the analysis means; and

comparing the second signal to a predicted raman spectrum to determine the second characteristic of the target region.

22. The measurement apparatus of claim 21, wherein the second characteristic comprises at least one of film thickness, strain/stress, deformation, defects, crystallinity, composition, and the like.

23. A method of measurement, comprising:

irradiating a first light to a target area of a measurement object by a first optical measurement system, and detecting a first signal generated by the target area of the measurement object in response to the first light;

irradiating a second light to the target region of the measurement object by a second optical measurement system as a raman scattering measurement system, and detecting a second signal including raman scattered light generated in response to the second light by the target region of the measurement object;

determining a first characteristic of the target region of the measurement object from the first signal; and

determining a second characteristic of the target region of the measurement object from the second signal and the first characteristic.

24. The measurement method of claim 23, wherein the first optical measurement system comprises at least one of an ellipsometry system and a reflection measurement system, and the first characteristic comprises a refractive index and a thickness of the film layer.

25. The measurement method of claim 23, wherein determining, from the first signal, a first characteristic of the target region of the measurement object comprises:

(b) Comparing the first signal to the simulation data;

26. The measuring method of claim 25, wherein operation (b) is performed by a non-linear fitting algorithm or a genetic algorithm.

27. The measurement method of claim 25, wherein the first optical measurement system is an ellipsometry system, the simulation data has a representation of a Mueller matrix,

wherein operation (b) comprises:

performing Fourier transform on the first signal measured by the ellipsometry measuring system to obtain a frequency light intensity component;

28. The measurement method of claim 23, wherein determining a second characteristic of the target region of the measurement object from the second signal and the first characteristic comprises:

predicting a Raman spectrum of the target region under the second light irradiation according to the first characteristic; and

29. The measurement method of claim 28, wherein the second characteristic comprises at least one of film thickness, strain/stress, deformation, defects, crystallinity, composition, and the like.