KR100447713B1 - Method and apparatus for showing scanning image of sample - Google Patents

Abstract

The present invention provides a scanning sample display technology capable of non-destructively observing a large and rough surface structure, which has been conventionally difficult, and a specific structure such as a structure, a defect, and a foreign material in a sample. In addition, application to inspection and measurement makes it possible to economically supply high quality and high reliability device components. For this purpose, the primary information generated by the scanning electron beam acting as a sample is formed by using secondary information such as secondary electrons generated as a result of the interaction with the sample as an image signal.

Description

Method and apparatus for showing scanning image of sample

The present invention relates to a method and apparatus for displaying a scanning image of a sample. Examples of the sample include semiconductor devices, photomask substrates including multilayered masks such as phase shift masks, display devices such as liquid crystals and CCDs, wiring substrates, devices such as storage media such as optical disks, metals and polymers. Material cell tissues, such as these, Other living bodies are mentioned.

The processing of device parts and the like is not a matter of being processed or finished products. TECHNICAL FIELD This invention relates to the effective technique used for the observation, inspection measurement, analysis, the monitoring technique at the time of sample processing, etc. for these.

For example, in the field of observation of the microstructure of a sample, a sample display device such as a scanning electron microscope using an electron beam of energy of several hundred eV to several tens of keV or a transmission electron microscope using an electron beam of several tens of keV to several MeV is used. It is used.

In addition, regarding the conventional sample display technology using such an electron microscope technique, for example, "The Basics and Applications of Scanning Electron Microscope" issued by Kyoritsu Publishing Co., Ltd. In the literature.

However, in the prior art as described above, there is a problem that it is difficult to observe the surface structure or the internal structure of the sample having a large size or a large size at high resolution or nondestructive.

It is an object of the present invention to provide a display sample on a scanning sample which will be able to observe a specific structure such as structure, defect, foreign matter, etc. inside the sample by nondestructive.

Another object of the present invention is to provide a scanning sample display technology capable of observing the size of the wafer or the surface structure or internal structure of the sample with a high degree of resolution at high resolution.

It is still another object of the present invention to provide a scanning sample display technology capable of obtaining three-dimensional information and tomographic information of a surface and an internal structure of a sample.

It is still another object of the present invention to provide a scanning sample display technology capable of observing non-conductive samples at high resolution.

Another object of the present invention is to provide a sample which can more effectively observe the surface structure and the internal structure by irradiation of high-energy particle beams.

The above and other objects and novel features of the present invention will become apparent from the description and the accompanying drawings.

A brief outline of the representative inventions disclosed in the present application is as follows.

That is, in the present invention, secondary electrons or light generated by irradiating a scanning particle beam to a sample and the first information such as backscattering particles, X-rays, and light generated by the scanning particle beam acting on the sample again interact with the sample. Etc., secondary information is used as a signal of the main image formation.

In one embodiment, an electron beam having an energy of 50KeV or more is used as a scanning particle beam, and secondary electrons or electromagnetic waves generated by the interaction of the sample with the reflected electrons generated by the irradiation of the electron beam as the secondary information and the sample are scanned. It constitutes a sample phase.

In another embodiment, at least one of the incident energy and the incident angle forms at least one of a monolayer and a three-dimensional phase based on a plurality of samples on the other two or more particle beams observed.

When the part to be observed, that is, the test part is inside the sample, the injection particle beam is required to satisfy the following requirements. One is that the scanning particle beam can penetrate the sample to reach the test part, and in addition, it interacts with the test part to generate primary information such as backscattering particles. This primary information must also have sufficient energy to interact with the sample and generate secondary information such as secondary electrons.

The scanning particle beam, i.e. the energy required for the primary beam, is determined in consideration of the degree of backscattering and forward scattering of the portion of the sample (the portion above the test part) on the path of the beam. The degree of scattering depends on known parameters (density, thickness, etc. of that part).

In backscattering the test part preferably has a large contrast around it, in particular with respect to the passage of the beam above it. In order to give contrast of backscattering between the two, the density and / or the crystal structure are different. Or attach the feature to the face of the test part to which the primary beam is irradiated. For example, the roughness can also be given to both.

The observation method of the test part can be applied to a measurement process of a semiconductor device including at least one of the following steps.

A first process of reading identification information of a sample and setting corresponding work instructions, work conditions, and work data based on the read identification information;

A second process that automatically performs the specified place, the specified time and the specified work on the specified sample based on the specified work order work condition, work data,

A third process of simultaneously displaying a plurality of images such as a sample image and a three-dimensional shape,

A fourth process of transmitting and outputting information such as work instruction, work condition, work data, detected image data, measurement data, etc. online with an external device,

A fifth process of positioning and / or calculating the particle beam with the sample,

A sixth process of measuring the dimensions and / or position coordinates of the pattern formed on at least one of the surface or inside of the sample,

A seventh process for automatically measuring one or more patterns in the sample, for the designated sample,

For the designated sample, the quality of the pattern is determined by combining the measured values of one or more patterns in the sample with a predetermined standard value, and the sample is processed according to a predetermined procedure based on the determination result. 8th treatment done,

The ninth treatment is used to measure the type, number, size, etc. of the sample structure such as particles and domains existing on the surface and / or inside of the sample.

A tenth process of automatically measuring one or a plurality of areas in the sample for a designated sample, obtaining a statistical processing result of the measured values, and displaying, storing or outputting the data as necessary;

An eleventh treatment for changing the irradiation direction and / or the irradiation angle of the sample of the particle beam,

A twelfth process of performing at least one of displaying, storing and outputting three-dimensional information based on a plurality of specimen images observed at two or more designated irradiation angles,

A thirteenth process of performing at least one of adjusting a particle such as focusing when changing the irradiation energy of the particle beam and changing the irradiation energy, and ensuring the same field of view when changing the irradiation energy,

At least the display, storage and output of the tomographic image and / or the three-dimensional image by constructing a tomographic image and / or a stereoscopic image based on a plurality of sample images observed in a particle beam having at least one of two or more specified incident energies and incident angles. 14th process of doing one,

A fifteenth process of applying at least one of one or a plurality of voltages, currents and electrical signals to the sample,

An operation of applying a predetermined voltage and / or current and / or an electric signal to a designated sample, an operation of obtaining a sample image of a specified region at a designated time, and an operation of detecting a change in comparison with a sample image of the designated region obtained first And a sixteenth process of performing at least one of the operation of obtaining transition data of the designated parameter of the specimen at a designated time and the operation of displaying and / or storing and / or outputting phase data and / or transition data,

17th process of arbitrarily setting the temperature of the sample,

For a designated sample, an operation of bringing the sample to a predetermined temperature, obtaining a sample image of the designated region at a designated time, and comparing the sample image of the designated region previously inputted, and detecting a change, An eighteenth process of performing at least one of an operation for obtaining transition data of a designated parameter and an operation for displaying and / or storing and / or outputting phase data and / or transition data,

For a designated sample, an operation of taking a sample image of a specified region and comparing it with a previously indicated memory image, extracting a difference between the sample image and the memory, and detecting a position coordinate in the sample of the difference portion, A nineteenth process of performing at least one of an operation of displaying and / or storing and / or outputting position coordinate data or the like,

A twentieth process for etching and / or depositing a designated one or a plurality of portions in the sample, for a designated sample,

A twenty-first process of performing component analysis of a specified one or a plurality of portions in the sample,

Twenty-second treatment of annealing the sample after observation by irradiation of particle beam

The present invention described so far has been newly completed by the present inventors.

In observation of a sample of a semiconductor device using a high energy scanning electron beam of 50KeV or more as the particle beam, the following phenomenon was found.

(1) The internal structure of the sample can be observed by nondestructive.

For example, a transmission electron microscope is generally used for observing the internal structure of a sample. In transmission electron microscopy, the sample must be thinned and the destruction of the sample is observed.

(2) A nonconductive sample can be observed in high resolution as it is.

For example, a scanning electron microscope is used for observation of the sample shape at high resolution. In the observation of a non-conductive sample by a scanning electron microscope, in order to prevent phase degradation due to overheating, gold or carbon is deposited on the surface of the sample to leak the accumulated charge, but a low energy electron beam of about 1 KeV is applied. A method of increasing the secondary electron emission amount to reduce the charge amount is adopted.

Deposition of the conductive film is observed to destroy the inherent physical properties of the sample, and becomes low resolution in the observation of low energy electron beam.

As a result of analyzing these phenomena, it was found that the reason for observing the internal structure was due to the following mechanism. A description with reference to FIG. 1 is as follows.

In general, a scanning electron microscope irradiates a sample 2 with a scanning electron beam 1a in an energy range of several hundred eV to 30 KeV and reflects primary information (reflected electrons) resulting from the interaction between the electron beam 1a and the sample 2. A sample image is displayed using mainly secondary electrons 5a as phase signals among 3a, electromagnetic waves 4a made of X-rays, light, etc.). Of course, X-rays, light, absorbed electrons, transmitted electrons, or the like may be used as the phase signal.

On the other hand, in the high-energy scanning electron beam 1b of the present invention, since the energy is high, the electron beam penetrates to the depth of the sample 2 and the scattering electrons 3b scattered from the internal structure 6 are collected from the sample 2. To escape. The scattered electrons 3b also generate secondary information such as the electromagnetic wave 4b and the secondary electrons 5b in accordance with the action of the sample 2 when exiting the sample 2.

Looking at the secondary electrons as the phase signal, there are more secondary electrons 5b as secondary information than secondary electrons 5a as primary information. Therefore, on the sample of the secondary electron signal, the amount of scattered electrons 3b reflected on the secondary electrons 5b, that is, the internal structure 6 can be observed.

2 shows a model relationship between the scanning electron beam energy and the secondary electron emission amount.

In general, the secondary electrons 5a of the primary information have peaks in the amount of emission with energy around several hundred eV, and at higher energy, the amount of emission decreases with increasing energy.

On the other hand, the secondary electrons 5b of the secondary information are not emitted until the beam energy exceeds the threshold value Eb. Where the energy exceeds the threshold value E _b , the emission of the secondary electrons 5b starts, and the amount of emission continues to increase with the increase of energy.

This is because when the energy of the electron beam 1b is low, the electrons 3b scattered back to the test part 6 do not give enough energy to reach the sample surface, so that the secondary electrons generated by the scattering electrons 3b are also deep. This is because the sample surface cannot escape from the sample surface. In other words, if the depth from the treatment surface to the test part 6 is d, the effective range of the electron beam 1b of energy E _b is considered to be approximately 2d. In addition, the escape depth of the secondary electrons is about 100 GPa, and the secondary electrons with energy of about 10 eV are the most. On the other hand, the amount of scattered electrons has a direction dependence that can be said to be the cosine law with respect to the scattering direction. That is, if the case where the electron beam 1b of FIG. 3 is incident perpendicularly to the sample 2 is taken as an example, the amount of scattered electrons decreases as the scattering angle θ becomes maximum in the direction of 0 ° and the θ becomes large. As a result, θ becomes 0 at 90 °. Quantitatively, θ occupies nearly 90% of the total scattered electron amount with scattered electrons from 0 ° to 60 °, and scattered electrons in this range may be considered as phase signals.

In these examples, let's look at the energy of the scanning electron beam in semiconductor device observation.

A semiconductor device generally consists of device portions such as transistors and capacitors, and wiring layers formed thereon. The depth of these device structure portions depends on the number of wiring layers and the like, but on average is about 5 mu m.

On the other hand, if the scattering electrons contributing as the phase signal source are within the range of 0 ° to 60 ° in the above-mentioned examination, the effective range of the scanning electron beam for escaping the scattering electrons from the sample surface is 15 µm in FIG. It turns out that it is necessary.

In order to convert the effective range of 15 μm into the energy of the scanning electron beam, the following equations of Katz and penfold (Revs. Modern. Phys., Vol 24:28 ('52)) are used.

Where R (mg / cm ² ) is the effective range and E (KeV) is the energy of the electron beam. In this effective range, the density (unit: mg / cm ³ ) of the sample is added.

The relationship between the effective range R and the energy E is shown in FIG. R is almost proportional to E ² .

Haebomyeon converted using a typical density of Si as a semiconductor material 2.34g / cm ^3, A1 density 2.69g / cm ³ as a wiring material in which, when the energy of the electron beam is in the range of about 50KeV the effective 17㎛, A1 of the Si The effective range is about 15 mu m.

From this, observation of a semiconductor device shows that electron beam energy of 50 KeV or more is required. In addition, the value of 50 KeV agrees well with the actual observational experience.

In addition, the reason why the non-conductive sample can be observed as it is is because most of the electron beam penetrates and penetrates into the sample depth, and the amount of charge in the vicinity of the sample surface is extremely small.

In addition, the observed contrast on the sample is complex not only due to the internal structure of the sample as described above, but also depending on the surface structure of the sample and the difference in partial materials.

For example, in the case where there is a surface roughness as shown in FIG. 6, when the scanning electron beam 1b irradiates the flat portion of the sample, when the stepped portion is irradiated, or the portion where the step is close is irradiated. In this case, the total amount of reflected electrons and direction dependence of the reflected electrons 3a reflected from the sample surface change. That is, the number of electrons that can invade into the sample and become the scattering electrons 3b, the amount of secondary electrons that can be generated and become a phase signal, secondary electrons 5a of primary information, and secondary of secondary information. The composition ratio of the former 5b has also changed.

Also, as shown in FIG. 7, the number of electrons that enter the scattering electrons in the sample in the case where the sample material is different from 2a and 2b or when the heterogeneous material 2c adheres to the sample surface, etc., Further, the details of the total amount of secondary electrons detected and the secondary electrons 5a and 5b are changed. These cause one of the contrasts on the sample.

In addition, as shown in FIG. 8, even in the case where the structures 2d and 2e are designed to shield the electron beam 1b, the shielding structure having a thickness and depth through which the electron beam 1b can penetrate, Contrast arises in the parts D and E which become shadows, and it becomes possible to observe as a sample image. In other words, this indicates that the surface of the inside of the ridge, the bottom, and the side surface of the ridge can be observed even when there are very large ridges and rough edges on the sample surface.

The above objects and effects will become apparent from the following described embodiments and the accompanying drawings.

Hereinafter, embodiments of the present invention will be described.

First, an example in which a high energy electron beam is used as the particle beam, that is, an example in which the present invention is applied to a scanning electron microscope will be described with reference to FIG.

First, the sample 2 is moved and loaded onto the sample stage 21 in the sample chamber 22 from the loader / unloader chamber 20 via the loader / unloader mechanism. The loader / unloader chamber 20 is isolated from the sample chamber 22 by the vacuum valve 23 and the sample 2 can be loaded on the sample stage 21 without breaking the vacuum of the sample chamber 22. It has a load lock mechanism. Subsequently, the electron beam 1b emitted from the electron gun 15 is accelerated by energy of several tens of KeV or more by the acceleration tube 1b, and then collected in detail by the converging lens 17 and the objective lens 18 so that the sample 2 The sample 2 is scanned while receiving XY deflection by the deflector 19.

The mechanism for moving the sample and the sample stage 21 have the same configuration as that of the appearance inspection apparatus (trade name: S-700) manufactured and sold by Hitachi Corporation. The electron gun 15, the accelerator tube 16, and the converging lens 17 are similarly the same as those of the transmission electron microscope (brand name H-800) manufactured and sold by Hitachi Corporation.

In the portion of the sample irradiated with the scanning electron beam 1b, electromagnetic waves 4b such as secondary electrons 5b, X-rays, and light are emitted.

The secondary electrons 5b are wound upward by the magnetic field of the objective lens 18 and are drawn upward in the axial direction of the objective lens 18, and the secondary electron detector 24 made of a scintillator / photoelectron heavy pipe or the like. Is detected and converted into an electrical signal.

This electrical signal is amplified by the signal amplification processing unit 25, and then the display 26 is displayed on the display 26 by modulating the display 26 with luminance.

Similarly, the electromagnetic wave 4b such as X-rays or light emitted from the sample 2 is detected by the detector 27 and used for analysis or image display.

The sample stage 21 is composed of an X, Y moving mechanism 21a and a rotation / inclination mechanism 21b so as to arbitrarily select an observation place and an observation direction.

An example of the flow of scanning and processing is shown in FIG. 10 for the case where the semiconductor wafer is treated as a sample 2 in the unit of a lot.

The wafer as the sample 2 is stored in a wafer carrier in a lot unit. When the wafer carrier is set in the loader / unloader chamber 20, the lot number recorded on the wafer carrier is read by an optical or magnetic reading device, and the device is started. Subsequently, the work instruction, work condition and work data corresponding to this lot number are read. Based on this work instruction, work conditions, and work data, the following processing is automatically performed.

In addition, the work instruction defines the work content such as how much work is done in which place on which wafer. The working conditions are related to the electron beam irradiation, image forming process, measurement process, etc. at the time of performing the work, and define the device parameters required for the work performance. The work data corresponds to data other than the device parameters necessary for the work, for example, position coordinate data of a defect transmitted from an external tester or a defect inspection apparatus.

As a process, one wafer designated first is loaded into the sample stage 21. Subsequently, wafer alignment is performed in accordance with the alignment method in the electron beam exposure apparatus. The combination of wafer positions may be performed before loading to the sample stage 21. For example, it is a method of optically detecting the outer shape of a wafer to obtain the center of the wafer. Precise positioning of the wafer is performed by scanning the alignment mark formed on the wafer with the electron beam 1b to obtain the alignment mark position from the signal waveform of the reflected electrons, or the reference image in which the alignment mark scan image is stored in advance. And the like to find the alignment mark position.

After completion of the custom work, the work such as observation, inspection, measurement or analysis is performed as the present work. These operations may be performed alone, but may be performed by combining a plurality of operations, for example, observation-analysis. The image data, the inspection data, the measurement data, the analysis data, etc. of the sample as the work result are used for storage, display or transfer to an external host computer, an analysis device, a wafer processing device, etc. in accordance with a predetermined procedure after predetermined data processing.

As a method of carrying out the work, any plurality of work in the wafer, repetitive work at any time in the same place in the wafer, and the like are possible.

It is also possible to change the work contents for each wafer or for each work place in the wafer. These work contents may be input via the control computer of the apparatus, or may be input online from a higher host computer.

The above operation is performed for the entire designated wafer.

Hereinafter, the specific example of this operation is described.

One of the inspection works is the measurement of length. 11 shows an example of the explanation.

In the secondary electron signal waveform obtained by scanning the pattern 7a formed on the surface of the sample 2 and the pattern 7b formed therein with the electron beam 1b, the pattern dimensions W and W ¹ and the distance between patterns ( D), pattern position coordinates (P, P ¹ ) and so on. The specific method of length measurement generally follows the method used for length measurement (SEM). The electron beam 1b has an energy of at least 50 KeV, and therefore, as can be seen from the relationship of FIG. 2, the signal corresponding to the first pattern 7b is generally higher than the signal corresponding to the second pattern 7a. Big.

In this case, as shown in FIG. 12, if the pattern 7a is arranged in a state similar to A in which the pattern 7a is applied to the scanning line 1S of the electron beam near the pattern 7b to be measured, the length measurement is performed. There is a risk of going wrong. It is preferable to arrange | position the patterns 7a and 7b in isolation | separation more than the width | variety of a scanning line, as shown as scanning line 2S in a length measurement location.

In addition, as illustrated in FIGS. 13 and 14, it is also possible to obtain a three-dimensional shape on two or more identical visual fields having different viewing angles or viewing directions, and display the three-dimensional shape based on this, and to measure the length of the three-dimensional dimension. . For example, the irradiation angle between the electron beam 1b and the sample 2 is obtained by obtaining two different field of view images with 0 ° (observed from the top) and α (observed from the top of the slope) and two different visual fields. The three-dimensional shape is calculated from the distance difference between two points to be measured. That is, on the sample with an irradiation angle of 0 °, the distance between two points in the horizontal direction is seen as a real dimension, while the distance in the longitudinal direction is shown as 0.

On the other hand, on the sample of the irradiation angle (alpha), the horizontal direction is x cos alpha, and the longitudinal direction is reduced by more than the actual size by x sin alpha.

The irradiation angle may be changed by changing the incidence angle of the electron beam 1b with respect to the sample 2 or changing the inclination angle of the sample stage 21 using a deflector. The irradiation direction and the angle are not limited to two steps. Fidelity and precision of the three-dimensional shape to be calculated are improved by obtaining a large number of sample images inclined in the direction where the shape is to be observed and measured in length. By narrowing the scanning width of the electron beam, a substantial cross section can be formed with high accuracy.

About the display, it is also possible to simultaneously display a plurality of images such as a combination of a sample image and a three-dimensional image. Simultaneous display may be a method of displaying on the same display or a method of displaying on another display.

Specific examples of the use of the function include a pattern size measuring instrument, a pattern position coordinate measuring instrument, a precision measuring instrument overlapping between patterns, a pattern drawing distortion or a transfer distortion measuring instrument, and the like.

In particular, the accuracy of overlapping patterns between patterns cannot be measured in a conventional electron beam application apparatus because the pattern located in the sample cannot be measured. This embodiment makes it possible.

As a 2nd example, measurement of particle | grains, a domain, a bubble, a foreign material, etc. is mentioned.

An example of particle measurement is shown in FIG. 15A. The sample image is obtained by scanning the specified region of the sample 2 in the scanning electron beam 1b. This sample image is analyzed to count the number of particles and to obtain data such as size distribution and intra-wafer distribution. In this case, the analysis method such as particle count is based on the method of a general image analysis device.

It is also possible to perform particle component analysis in addition to the measurement. The component analysis obtains the positional coordinate data of the particle 8c to be subjected to component analysis from the sample, calculates the positions of the electron beam and the analyte particle based on this, and then irradiates the electron beam 1b on the target particle 8c. And detecting the characteristic X-rays 9 emitted from the particles 8c and determining the same components. For X-ray detection, a method of determining the type and amount of elements equally in crest value and number of current pulses generated by incident X-rays using a semiconductor detector is applied.

At this time, it is also possible to remove the coating on the particles 8c in order to increase the sensitivity and the accuracy in which the components are equally set. Optional removal of the coating on the particles is carried out, for example, by laser assist etching as shown in FIG. 15B. This is to irradiate the portion to be etched into the laser beam 10 that is thinned while blowing off the etching gas 12 from the gas nozzle 11. The etching gas selects a gas having only selectivity to etch the coating and not damage the particles.

In the case where the target sample covers a plurality of types, it is possible to select a suitable gas type with a plurality of gas nozzles.

In addition, in order to optimize the etching conditions, the horizontal and vertical positions of the gas nozzles, and the direction in which the gas is blown are made movable and adjustable.

Of course, the method of component analysis can detect information such as Auger electrons and cathode luminescence instead of X-rays. In addition, the qualified beam used for analysis is not limited to an electron beam, You may use a lazy beam, an ion beam, etc.

Moreover, the etching method can also apply other chemical etching methods, such as ion beam assist etching other than laser assist etching, and physical etching methods, such as ion beam sputtering. However, in general, a chemical etching method is suitable in order to make the etching selectivity of the coating material and particles high.

In addition, in the particle measurement, as shown in FIG. 16, an example of the processing flow, a plurality of sample images having different irradiation directions and angles are obtained, and three-dimensional shape processing is performed to determine how many particles are in the three-dimensional shape or any depth position of the particles. Information in the depth direction can be obtained whether is distributed.

In addition, knowledge of the crystal orientation can be obtained by changing the irradiation direction angle to observe the sample. The example is shown in FIG.

The sample 2 has a polycrystalline structure 6 (internal structure), the crystal direction of which the crystal grain 6a has the inclined direction, the crystal grain 6b has the vertical direction, and the crystal grain 6c has the horizontal direction. When the sample is observed from the scanning electron beam 1b at the top, the amount of scattered electrons 3b directed to the sample surface, that is, the amount of image signals is the largest at 6c and the lowest at the order of 6a and 6b. On the other hand, when observed from the scanning electron beam 1b 'irradiated in the oblique direction, the magnitudes of the image signal amounts decrease in the order of 6c, 6b, 6a.

In this way, the phase signal amount, that is, the image contrast, changes depending on the relationship between the crystallization direction and the observation direction. By analyzing this change situation, the crystal direction of each crystal grain can be discriminated. In addition, by performing image analysis such as particle number measurement, data such as size distribution of crystal grains and crystal direction distribution can be obtained.

As a third example, there are inspections of pattern defects and foreign objects. For example, as a defect, there exist a kind as shown to FIG. 18A and FIG. 18B. 18A is a sectional view of a sample, and FIG. 18B is a plan view. The defect inspection adopts the procedure shown in Figs. 19 and 20 in accordance with the method used as a general defect inspection apparatus to detect these defects.

First, a sample image of a designated area is obtained, and image processing such as smoothing is performed. Then, alignment and comparison are performed with a previously stored reference image, and defects and foreign matters are detected from the difference between the sample image and the reference image. In Fig. 19, part B is detected as defective.

The reference image may be a standard sample image taken in an area corresponding to a designated area in the same sample or the same type of sample, or may be a pattern data image of a corresponding area created based on pattern data. In addition, it is also possible to use a part of a standard sample as a reference image during the inspection operation, and to use a combination of the pattern data image as a reference image.

The inspection area may be the entire surface of the wafer or may be partially inspected. For example, the position coordinate data of a chip or a circuit block that is determined to be defective or defective as a result of a test by a tester or a defect inspection device is inputted online by a tester or a defect inspection device, and the defect to be inspected by the input coordinate data is checked. Locate the chip and the defective circuit block and selectively inspect only that part. On the other hand, also in defect inspection, the component analysis of a defect part can be performed similarly to the example of particle measurement.

In addition, pattern defects can be corrected by using a method such as removing a coating film by etching gas. However, etching gas is used to remove defects and isolation defects, but sedimentary gas is used to repair defects. These defect repair techniques are basically the same as those used in the defect repair apparatus of the photomask and the wiring repair apparatus of the LSI.

In addition, although a conventional defect inspection apparatus is generally optical, a feature of using a high-energy electron beam is that the defect detection under an opaque material can be detected in addition to the fact that the defect detection sensitivity is high. In particular, the detection of the pattern position shift among the defects shown in FIG. 18 enables the detection by the conventional method.

Fourth, there is an example of monitoring the change of state of a sample. 21B shows an application of the semiconductor device to an acceleration test as an example. The probe 13 is applied to both ends of the wiring pattern 7 to be monitored, and the stress current supplied from the current source 14 is applied through the probe 13. The sample image of the wiring pattern 7 is obtained at every designated time, and the state until the wiring pattern 7 reaches the disconnection is recorded and displayed. The display is performed by, for example, taking a difference from the previous state and emphasizing only the change. At the same time as the sample phase, trends of electrical parameters such as current value and resistance value are also collected and recorded. Of course, the number of probes and power supplies to be used can be added according to the number of wirings to be monitored. 21A is a cross sectional view showing a wiring pattern embedded in a sample.

The applied stress is not limited to the direct current, but may be an alternating current or a pulsed current. In addition to the current, it is also possible to apply a voltage or an electric signal for operation, or to heat or cool the sample to observe and monitor the change caused by temperature. In the case of heating, care should be taken because light emission from the hot electrons and the heating portion acts as noise of the phase signal. Moreover, you may combine and add these multiple addresses simultaneously. In addition, the mechanism for applying these stresses to a sample conforms to the method used by the conventional scanning electron microscope observation.

The fifth observation technique is tomographic observation. The change in the information of the sample depth direction obtained depending on the energy of the electron beam is used.

22 shows an example of the processing flow. A sequential sample image is obtained while changing the acceleration voltage of the electron beam.

First, after setting an acceleration voltage, it secures the same field of view as the adjustment of an electron beam. The adjustment of the electron beam is to perform axis alignment, focusing, and astigmatism correction in order to maintain high resolution conditions. The same field of view ensures that the same field of view can always be observed even if the acceleration voltage is changed. For example, based on the sample image obtained earlier, a method of adjusting the scanning area of the electron beam is adopted so that the sample image observed under the reference image coincides. Alternatively, the object in the image designated according to the alignment method used in the electron beam exposure apparatus may be used in place of the alignment mark for positioning.

Next, the sample image of the designated area is received. The received sample image has information up to a deeper portion when the set acceleration voltage is higher.

For example, consider a case where the wiring patterns 7b, 7b ', and 7b "exist inside the sample 2 as shown in FIG.

If the set acceleration voltage is relatively low and the chipping depth of the scanning electron beam 1b is close to the wiring pattern 7b positioned at the depth d, the wiring pattern 7b is visible in the obtained sample image A, Wiring patterns 7b 'and 7b "located therein are not observed.

On the other hand, when a relatively high acceleration voltage is applied and the chip depth of the electron beam 1b 'reaches the wiring patterns 7b' and 7b "positioned at d ', the wiring patterns 7b', 7b ") is observed.

Therefore, when a difference image between the sample image A 'and the sample image A is made, an image of only the tomographic image A' near the depth d ', that is, the wiring patterns 7b' and 7b "is obtained. It is also possible to obtain the three-dimensional shape inside a sample by combining the several tomographic images obtained in this way.

In addition, in the normal sample phases A and A ', the signal level and contrast are different. Therefore, as a preprocess for obtaining a highly accurate difference image, it is necessary to match the signal level and the magnitude of contrast between the sample images A and A '.

24 shows an example of preprocessing for obtaining the difference signal. The phase signals on the sample phases A and A 'are subjected to AND processing first. In this AND process, the presence or absence of an image signal is compared for each pixel and divided into a portion C having an image signal only on the A 'phase and a portion D having a signal on both the A and A' phases.

In this case, the portion of C corresponds to the wiring pattern 7b 'and is used as a single layer signal as it is.

On the other hand, the signal level matching and contrast matching processing are further performed for the portion of D, and the result is subtracted. The difference signal E after the subtraction process corresponds to the wiring pattern 7b ", which is combined with the signal of the C portion to form a single layer A 'signal. In the embodiments shown in Figs. The incident energy of the secondary beam is varied, and as shown in Figs. 13 and 14, the incident angle of the primary beam is changed, whereby a tomographic or three-dimensional image of the pattern can be formed more accurately.

The problem when irradiating an electron beam to a semiconductor device is damage of irradiation of a device. Irradiation damage deteriorates Diabis characteristics, so it is essential to reduce or recover damage.

As a result of examining the cause of the irradiation damage, as shown in FIG. 25, the high-energy reflected electrons 3 scattered between the sample 2 and the lower surface of the objective lens 18 on the sample, It can be seen that this multi-scattering is a major cause of great damage.

26 is an enlarged cross-sectional view of a sample objective lens in order to examine countermeasures against multiscattering of reflected electrons.

As shown in FIG. 26A, in the past, the vacuum shield pipe 28 made of phosphor bronze was passed through an electron beam path formed by the upper magnetic pole 18a and the lower magnetic pole 18b of the objective lens. However, phosphor bronze is easy to multi-scatter because of its large reflection coefficient.

26B shows a method of reflecting electron multiscattering suppression. The sample counter portion 28a facing the sample 2 of the vacuum shielded pipe 28 is made of light element using carbon having a small electron reflection coefficient, and it is difficult to scatter the reflected electrons in the cross-sectional shape. It is serrated.

The material of the sample opposing portion 28a may be a light metal material such as aluminum. The shape is not limited to the sawtooth shape, but is also a non-flat shape such as a comb.

On the other hand, regarding the recovery of the irradiation damage, for example, it is confirmed that the threshold value of the MOS device shifted by the electron beam irradiation at the time of observation is restored by 450 ° C hydrogen annealing. After observation, it is necessary to anneal the sample depending on the use. After observation, it is best to be able to anneal the sample continuously.

For the annealing function, a heating mechanism provided on the sample stage 21 may be used, a heating mechanism may be added to the loader / unloader chamber 20, or may be a separate unit. The heating may be a resistance heating method or a lamp heating method. In addition, gas such as hydrogen and nitrogen can be introduced into the annealing unit.

In the above embodiment, the secondary electron detector 24 is installed on the upper side of the objective lens 18, and the secondary electron is collected using the magnetic field of the objective lens. You may use the system which mounts an electron detector and detects a secondary electron by the applied electric field.

Alternatively, the secondary electron detector may use a secondary electron heavy pipe instead of the scintillator photomultiplier pipe.

In addition, the secondary information used as a signal may detect X-rays, light, absorption electrons, etc. other than secondary electrons.

Further, in order to increase the signal amount of the secondary information, a substance that is likely to generate secondary electrons, fluorescence, or the like may be deposited or applied thinly on the sample to be observed. FIG. 27 shows an example. The oxide material having a high secondary electron emission rate is deposited thinly on the sample 2, and the number of secondary electrons generated by the scattering electrons 3b is increased. As another example, instead of the oxide, a fluorescent material may be applied thinly and light emission of the fluorescent material by scattered electrons may be detected.

The sample is not limited to the wafer, but may be a device assembled into a package.

In addition, although the process of a sample is not limited to the lot process, it can respond also to the sheet (morning) process. In addition, the removal of the sample may be made to be automatically transported to another processing device instead of being performed by an operator.

In addition, instead of moving, rotating, and inclining the sample stage, the movement, rotation, and inclination of the specimen observation place may be moved by moving the irradiation position of the electron beam and inclining the rotation irradiation direction in the irradiation area.

The particle beam to be used is not limited to an electron beam, but other qualified beams such as an ion beam or a laser beam may be used.

In addition, primary information for obtaining secondary information is not limited to scattered electrons, but electromagnetic waves or the like may be used.

Further, the target sample is not limited to a semiconductor device, and may be a photomask substrate, a display device, a wiring board, an optical disk or a metal material, a polymer material, a living body, or the like. In the case of a light element such as a living body, it is also possible to dye with a heavy metal to increase the contrast.

The effects obtained by the representative of the inventions disclosed herein will be briefly described as follows.

According to this invention, it becomes easy to become difficult or impossible conventionally by applying the above-mentioned newly discovered phenomenon. Examples of effective uses are as follows.

In terms of observation,

① You can observe the structure, defects, and foreign materials inside the sample.

② Compared to the previous one, the larger the rougher the rough surface structure can be observed.

③ The three-dimensional shape of the surface and internal structure can be obtained.

④ can be observed tomography.

⑤ Non-conductive material can be observed at higher resolution than in the prior art.

And the like effect is obtained.

In terms of inspection and measurement,

① It can measure the length and height of the pattern or structure formed on the inside and the surface of the sample.

② Count and measure the particles, domains, bubbles, and dissimilar materials on the inside and the surface of the sample.

③ It can inspect the pattern defect and foreign substances on the inside and the surface of the sample.

④ Changes in the sample interior and surface structure can be monitored on the spot.

(5) Compared with the related art, effects such as more accurate length measurement, measurement, more sensitive defects, and foreign material inspection can be obtained.

In the defect inspection or the like, a combination of the component analysis function and the defect correction function can be used for more efficient work.

In addition, it can be applied as an inline process monitor by combining with other processing apparatus.

In addition, by applying the present method, it is possible to realize such a conventionally impossible or difficult matter as described above, so that it is possible to economically manufacture a device and a component having higher material and higher reliability.

Although the invention has been described in detail and clearly, it is only a description and examples, and the spirit and scope of the invention are limited only by the appended claims.

1 is a conceptual diagram schematically showing the principle of the display sample on the scanning sample of the present invention,

2 is a diagram showing a model relationship between scanning electron beam energy and secondary electron emission amount,

3 is a conceptual diagram showing an example of the distribution of scattered electron amounts,

4 is a conceptual diagram for obtaining electron beam energy required for observation of a semiconductor device;

5 is a conceptual diagram for obtaining electron beam energy required for observation of a semiconductor device;

6 is a conceptual diagram illustrating an example of the change in contrast due to the situation of the sample surface;

7 is a conceptual diagram illustrating an example of the change in contrast due to the situation of the sample surface;

8 is a conceptual diagram illustrating an example of the change in contrast due to the situation of the sample surface;

9 is a schematic cross-sectional view schematically showing an example of the configuration of a display device for scanning samples which is one embodiment of the present invention;

10 is a flowchart showing the operation of the display device of the embodiment;

11 is a conceptual diagram showing an example of a length measuring method according to an embodiment of the present invention;

12 is a plan view of the sample of FIG.

13 is a conceptual diagram showing a method for obtaining a three-dimensional shape of a sample according to one embodiment of the present invention;

14 is a flowchart of an embodiment for obtaining a three-dimensional shape of a sample;

15A is a conceptual diagram showing an example of observing particles in a sample;

15B is a conceptual diagram showing a method of removing a sample on a particle by etching;

16 is a flowchart in the case of observing particles,

17 is a conceptual diagram showing the method of the embodiment for obtaining the crystallographic direction of the crystal grains in the sample;

18A is a sectional view showing an example of a kind of defect to be subjected to defect inspection,

18B is a plan view showing an example of types of defects subject to defect inspection,

19 is a conceptual diagram showing the method of the embodiment for performing defect inspection of a pattern in a sample;

20 is a flowchart of the method of the embodiment for performing defect inspection,

21A is a sectional view showing a pattern in a sample,

21B is a flowchart showing the method of the embodiment for observing the shape change when stressing the pattern;

22 is a flowchart of an embodiment for observing a three-dimensional structure of a pattern in a sample,

23 is a conceptual diagram of an embodiment of observing a three-dimensional structure,

24 is a conceptual diagram illustrating an embodiment of observing a cross section of a pattern in a sample;

25 is a conceptual diagram illustrating an example of multiple scattering of reflected electrons;

26A is a sectional view showing the structure of an objective lens of a conventional example;

26B is a sectional view showing a configuration of an objective lens of the embodiment;

27 is a schematic cross-sectional view showing the structure and action of the sample of the example.

Explanation of the Major Codes in the Drawing

1a, 1b ..... electron beam, 1S, 2S .....

2 ..... samples, 2a, 2b ..... different materials,

2c ..... heterogeneous material, 2d, 2e ..... sample structure,

3 ..... reflective electrons, 3a ..... reflective electrons (primary information),

3b ..... scattered electrons, 4a, 4b ..... electromagnetic waves,

5a ... secondary electrons, 5b secondary electrons,

6 ..... polycrystalline structure (internal structure), 6a, 6c ..... crystal grain (internal structure),

7 ..... wiring pattern, 7a, 7b ... wiring pattern,

8c ...... particles, 9 ..... characteristic X-rays,

10 ... laser beam, 11 .... gas nozzle,

12 ...... Etching gas, 13 ...... Probe,

14 ...... current source, 15 ...... electron,

16 ...... Accelerator tube, 17 ...... Procedure lens,

18 .. objective lens, 18a .. upper stimulus,

18b ..... lower stimulus, 19 ..... deflector,

20 ..... loader / unloader room, 21 ..... sample stage,

21a ..... X, Y moving mechanism, 21b ..... rotating, tilting mechanism,

22 ... sample chamber, 23 ... vacuum valve,

24 ..... secondary electron detector, 25 ..... signal amplification unit,

26 ... display, 27 ... detector,

28 ... Vacuum sealed pipe, 28a .. Sample facing part.

Claims (36)

As a method of displaying a scanning image of a sample, Irradiating a scanning electron beam with energy to reach a test part embedded in a sample, reflect from the test part, and escape from the surface of the sample; And the scanning electron beam interacting with the test part and with the sample to form an image of the sample including the test part based on secondary information resulting from the interaction with the sample. The method of displaying the scanning image of the sample characterized by the above-mentioned. The method of claim 1, Wherein said primary information is backscattering particles, X-rays, or light, and said secondary information is a secondary electron or light. The method of claim 1, The scanning electron beam is an electron beam having an energy of 50 KeV or more, the primary information is backscattered electrons generated by irradiation of the electron beam, and the secondary information is generated by interaction of the backscattered electrons and the sample. A method of displaying a scanning image of a sample that is secondary electrons or electromagnetic waves. The method of claim 1, At least one of the particle energy and the incident angle obtains two or more of the phase-forming signals using two or more of the scanning electron beams, and displays the scanning image of the sample which forms a monolayer or three-dimensional image of the sample based on the two or more signals. How to. As a method of observing a test part of a sample below the surface of the sample, Irradiating the test part with energy that reaches a test part embedded in the sample, reflects from the test part, and escapes from the surface of the sample; Observing the test part using primarily the secondary information generated when the scanning electron beam interacts with a portion other than the test part in the sample. How to observe the test part. The method of claim 5, wherein A method of observing a test part of a sample forming an image of the test part using the secondary information. The method of claim 5, wherein Observing a test part of a sample that obtains physical properties of the test part using the secondary information. The method of claim 5, wherein The scanning electron beam is an electron beam having an energy of 50 KeV or more, the primary information is backscattered electrons generated in the test part by irradiation of the electron beam, and the secondary information is the backscattered electrons and the test part of the sample. A method of observing a test part of a sample which is secondary electrons or electromagnetic waves generated by interaction with other parts. As a method of observing a test part below the surface of a sample and surrounded by the sample, A scan electron beam that passes through a sample surrounding the test part on the optical path, reaches the test part, reflects off the test part, and escapes from the surface of the sample. Irradiating a portion of the sample; Observing the test part using primarily the secondary information generated when the scanning electron beam interacts with a portion other than the test part in the sample. How to observe the test part. The method of claim 5, wherein And the sample is a semiconductor wafer, and further comprising adjusting the position of the wafer such that the scanning electron beam is irradiated to a portion including the test part of the wafer. The method of claim 10, Varying the energy of the scanning electron beam according to the wafer. The method of claim 9, And observing a test part between the sample surface and the test part, and adjusting the incident energy of the scanning electron beam based on at least one of a density and a thickness of a portion of the sample through which the scanning electron beam passes. How to. The method of claim 9, Adjusting the incident energy of the scanning electron beam based on the degree of scattering of the portion of the sample through which the scanning electron beam passes and between the sample surface and the test part and the degree of backscattering of the test part How to Observe Test Parts That Include The method of claim 5, wherein And the test part observes a test part of a sample which is a first wiring pattern. The method of claim 14, The scanning electron beam is irradiated to the second wiring pattern formed on the sample surface, and the second wiring pattern is based on the second primary information generated by the interaction between the second wiring pattern and the scanning electron beam. Observing the test part of the sample further comprising the step of observing. The method of claim 5, wherein The test part is irradiated with two or more scanning electron beams in which at least one of the incident energy and the angle of incidence is different to obtain two or more secondary information, and based on the two or more secondary information, tomographic or stereoscopic image of the test part. Observing the test part of the sample to form a. The method of claim 16, The test part is a method for observing the test part of the sample is a wiring pattern. The method of claim 16, And the test part is an arbitrary region of the sample, and the test part of the sample is observed in which a particle of a material having a different backscattering coefficient is displayed on the tomographic or three-dimensional image of the region. The method of claim 18, Irradiating a second particle beam on the displayed object; Interacting the second particle beam with the particles to generate second primary information from the object that characterizes the component of the object, Generating the second primary information; And measuring the second primary information and specifying a component of the particle. The method of claim 19, And the second primary information is a characteristic X-ray. The method of claim 19, Removing the sample on top of the particle by etching. The method of claim 16, And the test part is made of a material having a crystal structure partially different from each other, and a single layer or three-dimensional image of the region is formed to produce contrast corresponding to the crystal structure. The method of claim 6, The first image formed on the basis of the secondary information with respect to the test part is compared with the second image of the test part, which is obtained in advance, and is different from the first image and the second image. Iii) observing the test part of the sample further comprising extracting the portion. As a method of observing the state change of a test part of a sample below the sample surface, Applying stress to the test part; Observing the change of state of the test part of the sample comprising the step of observing the test part by the method of claim 5. The method of claim 5, wherein A method of observing a test part of a sample further comprising forming a layer of a material that generates a large amount of said secondary information on the surface of said sample. A method of manufacturing a semiconductor device requiring observation of a component below the surface, Irradiating the component with energy that reaches the component embedded in the sample, reflects from the component, and escapes from the surface of the sample; A semiconductor device comprising the step of observing the component mainly by using the secondary information generated by the primary information generated when the scanning electron beam interacts with the component, and the part other than the component in the sample. Manufacturing method. An apparatus for displaying a scanning image of a sample, Means for irradiating a scanning electron beam to the test part with energy to reach a test part embedded in the sample, reflect from the test part, and escape from the surface of the sample; Means for detecting secondary information generated as a result of the primary information generated by the scanning electron beam interacting with the sample; An apparatus for displaying a scanned image of a sample, comprising means for forming and displaying an image of the sample based on the detected secondary information. A device for observing a test part of a sample below the sample surface, And means for irradiating the test part with energy to reach the test part embedded in the sample, to reflect from the test part, and to escape from the surface of the sample. Means for detecting secondary information generated by the scanning electron beam interacting with the test part and the primary information generated by interacting with portions other than the test part in the sample; An apparatus for observing a test part of a sample provided with means for forming and displaying an image of the sample based on the detected secondary information. The method of claim 28, And said irradiating means observes a test part of a sample for scanning said test part with an electron beam having an energy of 50 KeV or more. The method of claim 28, An apparatus for observing a test part of a sample in which a portion of the irradiating means facing the sample is formed of a light element material. The method of claim 30, And the light element material is carbon. The method of claim 30, An apparatus for observing a test part of a sample having a non-flat shape in which a portion of the irradiating means facing the sample is non-flat. The method of claim 29, An apparatus for observing a test part of a sample further comprising means for annealing the observed sample. An apparatus for observing a test part below the sample surface and surrounded by the sample, The test part includes a scanning electron beam having energy passing through the sample surrounding the test part on the optical path, reaching the test part, reflecting from the test part, and escaping from the sample surface. Means for irradiating a portion of the sample to Means for detecting secondary information generated by the scanning electron beam interacting with a portion other than the test part in the sample by the primary information generated by interacting with the test part; An apparatus for observing a test part comprising means for forming and displaying an image of the sample based on the detected secondary information. The method of claim 28, An apparatus for observing a test part of a sample in which the sample includes a layer of a material on the surface of which is easy to generate the secondary information. 36. The method of claim 35 wherein A device for observing a test part of a sample, wherein the material likely to generate secondary information is an oxide or fluorescent material having a large amount of secondary electron emission.