Polarization microscope, crystal defect evaluation device, and crystal defect evaluation method

Abstract

To improve a technique for evaluating crystal defects.SOLUTION: The polarizing microscope 1 includes a sample stage 4 on which a sample 8 is placed, a polarizer 3 provided on the light source side of the sample 8, and an analyzer 6 provided on the observation side of the sample 8. At least one of the polarizer 3 and the analyzer 6 is installed so that the polarization direction is inclined with respect to the optical main axis of the sample 8, or installed so that an angle formed by the polarization direction of the analyzer 6 and the polarization direction of the polarizer 3 is deviated from a right angle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technique for evaluating defects in crystals using a polarizing microscope. [Background technology]

[0002] Power devices, which are semiconductor devices that convert and control electric power, are widely used in fields such as home appliances, industrial equipment, automobiles, railways, high-voltage direct current transmission, wind power generation, and solar power generation. Currently, silicon (Si) is the main semiconductor used in power devices, but with the aim of achieving even higher performance, silicon carbide (SiC) is attracting attention as a semiconductor material for next-generation power devices. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Polymorph Control in SiC Crystal Growth: Proposal of a Kinetic Polymorph Control Method (Example of 3C-SiC Solution Growth)," Journal of the Japanese Society for Crystal Growth, Vol. 40, No. 4, pp. 253-260 Summary of the Invention [Problem to be solved by the invention]

[0004] Improvements in SiC crystal growth technology have significantly reduced macroscopic defects, but numerous microscopic defects such as edge dislocations, screw dislocations, and basal plane dislocations still remain, adversely affecting the long-term reliability and characteristics of devices. Technology to accurately evaluate defects in semiconductor crystals is needed.

[0005] The present disclosure has been made in view of such problems, and its purpose is to improve the technology for evaluating defects in crystals. [Means for solving the problem]

[0006] In order to solve the above problems, a polarizing microscope according to an embodiment of the present disclosure includes a mounting portion for mounting a sample, a polarizer provided on the light source side of the sample, and an analyzer provided on the observation side of the sample. At least one of the polarizer and the analyzer is installed so that the polarization direction of the polarizer is tilted with respect to the principal optical axis of the sample, or so that the angle between the polarization direction of the analyzer and the polarization direction of the polarizer is deviated from a right angle.

[0007] Another aspect of the present disclosure is a crystal defect evaluation device including an image acquisition unit that acquires an image observed by the polarizing microscope, and a defect evaluation unit that evaluates defects contained in a sample based on the image acquired by the image acquisition unit.

[0008] Yet another aspect of the present disclosure is a crystal defect evaluation method, comprising the steps of acquiring an image observed by the polarizing microscope described above, and evaluating defects contained in a sample based on the acquired image.

[0009] Yet another aspect of the present disclosure is a crystal defect evaluation method, comprising the steps of acquiring an image of a sample observed with a polarizing microscope and evaluating defects contained in the sample based on the acquired image, wherein the acquired image has contrast enhanced by shifting the polarization direction of at least one of a polarizer and an analyzer of the polarizing microscope from the principal optical axis of the sample or by shifting the polarizer of the analyzer from crossed Nicols.

[0010] Any combination of the above components, and conversion of the present disclosure into a method, device, system, recording medium, computer program, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0011] According to the present disclosure, techniques for evaluating crystal defects can be improved. [Brief explanation of the drawings]

[0012] [Figure 1]1 is a diagram schematically illustrating a configuration of a polarizing microscope according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a control device according to an embodiment. [Figure 3] 1 is a diagram showing a configuration of a crystal defect evaluation apparatus according to an embodiment; [Figure 4] This figure shows polarized light observation images of threading edge dislocations with different Burgers vector directions, and polarized light microscope images calculated taking into account the shear stress distribution in the XY plane. [Figure 5] Figure 1 shows (a) an actually measured polarized light observation image of a threading edge dislocation contained in a crystal, and (b) a polarized light microscope image calculated taking into account the shear stress distribution in the Z direction caused by the threading edge dislocation. [Figure 6] FIG. 1 shows a polarized observation image of a threading edge dislocation contained in a crystal. [Figure 7] FIG. 10 is a polarizing microscope image calculated taking into account the shear stress distribution in the Z direction due to threading edge dislocations. [Figure 8] FIG. 1 is a diagram showing the inclination angle of a threading edge dislocation. [Figure 9] 1 is a flowchart showing the procedure of a crystal defect evaluation method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] In this disclosure, a technique for evaluating defects in crystals such as SiC using a polarizing microscope will be described.

[0014] 1 shows a schematic configuration of a polarizing microscope according to an embodiment. The polarizing microscope 1 includes a light source 2, a polarizer 3, a sample stage 4, an objective lens 5, an analyzer 6, and an eyepiece .

[0015] Light emitted from the light source 2 passes through a sample 8 placed on a sample stage 4 and is observed via an objective lens 5 and an eyepiece 7. A polarizer 3 and an analyzer 6 are provided in front of and behind the sample stage 4, respectively, and transmit linearly polarized light whose electric field oscillates in only one direction. In this embodiment, the sample 8 is observed in a state where the transmission axes of the polarizer 3 and the analyzer 6 are orthogonal to each other (crossed Nicols).

[0016] When an optically isotropic sample with no anisotropy in refractive index is placed on the sample stage 4, the polarization state of the linearly polarized light emitted from the polarizer 3 does not change when it passes through the sample, and therefore the light that has passed through the sample does not pass through the analyzer 6, which is placed so that its transmission axis is perpendicular to the polarizer 3. Therefore, the image observed through the eyepiece 7 is a dark field.

[0017] When an optically anisotropic sample with birefringence, in which the refractive index varies depending on the polarization direction, is placed on the sample stage 4, if the vibration direction of the linearly polarized light emitted from the polarizer 3 is aligned with the optical axis of the sample, the polarization state of the linearly polarized light does not change as it passes through the sample, and the image observed through the eyepiece 7 is a dark field, just as in the case of an optically isotropic sample. On the other hand, if the vibration direction of the linearly polarized light emitted from the polarizer 3 is different from the optical axis of the sample, the light emitted from the polarizer 3 is split into two polarized components due to the birefringence of the sample as it passes through the sample, and these polarized components interfere with each other, changing the polarization state, so that the light transmitted through the sample passes through the analyzer 6. Therefore, the image observed through the eyepiece 7 is a bright field, and a contrast in polarization intensity corresponding to the optical path difference (retardation) of the two split light beams is observed.

[0018] When a crystal contains defects, birefringence occurs due to the stress caused by the defects, and contrast can be observed using a polarizing microscope 1. This phenomenon can be used to non-destructively observe defects in crystals such as SiC. Observation of dislocations in crystalline materials using stress-induced birefringence has typically been performed along the principal optical axis.

[0019] However, research by the present inventors has revealed that a clearer contrast can be obtained in the polarized observation image by shifting the polarizer 3 from the extinction angle or the analyzer 6 from the crossed Nicols position. It has also been revealed that the results of theoretical calculations of polarized light microscope images of crystals, taking into account the shear stress distribution caused by defects in the crystal, correspond to the contrast observed with the polarized light microscope 1. Therefore, by observing a sample with the polarized light microscope 1 in which the polarizer 3 and the analyzer 6 are set slightly off the extinction angle or the crossed Nicols position, and comparing the observed contrast with the calculation results of the polarized light microscope image of the crystal that takes into account the shear stress distribution caused by defects in the crystal, it is possible to more accurately evaluate defects in the crystal.

[0020] In the polarizing microscope 1 of this embodiment, at least one of the polarizer 3 and the analyzer 6 is installed so that the polarization direction is inclined with respect to the optical principal axis of the sample 8, or so that the angle between the polarization direction of the analyzer 6 and the polarization direction of the polarizer 3 is deviated from a right angle. The angle (deviation) between the polarization direction of the polarizer 3 or the analyzer 6 and the optical principal axis of the sample 8, or the angle (deviation) between the polarization direction of the polarizer 3 and the polarization direction of the analyzer 6, is adjusted so as to observe clearer contrast depending on the type, crystalline structure, thickness, and type, size, number, and orientation of the defect to be observed of the sample 2. The polarizer 3 and the analyzer 6 may be fixed at a predetermined angle, or may be provided so that the angle is variable. In the latter case, the polarizing microscope 1 is equipped with a control device 10 for controlling the angle of the polarizer 3 or the analyzer 6.

[0021] 2 shows the configuration of a control device according to an embodiment. The control device 10 includes an input device 11, a storage device 30, and a processing device 20.

[0022] The input device 11 transmits instructions input by a user of the polarizing microscope 1 to the processing device 20. The input device 11 may be a mouse, a keyboard, a touchpad, or the like.

[0023] The storage device 30 stores programs, data, etc. used by the processing device 20. The storage device 30 may be a semiconductor memory, a hard disk, etc. The storage device 30 stores an angle information storage unit 31.

[0024] The angle information storage unit 31 stores the correspondence between information about the sample 2, such as the type, crystalline structure, thickness, type, size, number, and orientation of defects to be observed, and the angle of the polarizer 3 or analyzer 6.

[0025] The processing device 20 includes a specimen information acquisition unit 21, an angle determination unit 22, and an angle adjustment unit 23. These components are realized in hardware by any circuit, a computer CPU, memory, or other LSI, and in software by a program loaded into memory, but the functional blocks realized by the cooperation of these components are depicted here. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various ways, such as by hardware alone or a combination of hardware and software.

[0026] The sample information acquisition unit 21 acquires information about the sample 2 from the user via the input device 11. The sample information acquisition unit 21 acquires information such as the type, crystalline structure, thickness, and type, size, number, and orientation of defects to be observed of the sample 2, for example.

[0027] The angle determination unit 22 determines the angle of the polarizer 3 or the analyzer 6 based on the information about the sample 2 acquired by the sample information acquisition unit 21 and with reference to the angle information storage unit 31 .

[0028] The angle adjustment unit 23 controls a driving unit such as a motor for changing the angle of the polarizer 3 or the analyzer 6, and adjusts the angle of the polarizer 3 or the analyzer 6 to the angle determined by the angle determination unit 22.

[0029] This allows the angle of the polarizer 3 or the analyzer 6 to be adjusted depending on the sample 2 so that the contrast corresponding to defects in the sample 8 can be observed more clearly, thereby improving the accuracy of defect evaluation.

[0030] 3 shows the configuration of a crystal defect evaluation device according to an embodiment. The crystal defect evaluation device 50 includes a communication device 51, a display device 52, an input device 53, a storage device 70, and a processing device 60. The crystal defect evaluation device 50 may be a server device, a device such as a personal computer, or a portable terminal such as a mobile phone terminal, a smartphone, or a tablet terminal.

[0031] The communication device 51 controls communication with the polarizing microscope 1 and the like. The communication device 51 may perform communication using any wired or wireless communication method. The display device 52 displays a screen generated by the processing device 60. The display device 52 may be a liquid crystal display device, an organic EL display device, or the like. The input device 53 transmits instructions input by a user of the crystal defect evaluation device 50 to the processing device 60. The input device 53 may be a mouse, a keyboard, a touchpad, or the like. The display device 52 and the input device 53 may be implemented as a touch panel.

[0032] The storage device 70 stores programs, data, etc. used by the processing device 60. The storage device 70 may be a semiconductor memory, a hard disk, etc. The storage device 70 stores a stress distribution storage unit 71.

[0033] The calculated image storage unit 71 stores information about defects in the sample and polarizing microscope images calculated in consideration of the shear stress distribution caused in the sample by the defects, in association with each other. The information about the defects may be, for example, the type, number, size, position, shape, direction, angle, etc. of the defects. The candidate image storage unit 71 stores a large number of polarizing microscope images (hereinafter also referred to as "calculated images") calculated by changing at least one of the type, number, size, position, shape, direction, and angle of the defects in order to evaluate the type, number, size, position, shape, direction, angle, etc. of the defects contained in the sample.

[0034] The processing device 60 includes an image acquisition unit 61, a defect evaluation unit 62, and a polarizing microscope image calculation unit 63. These components are realized in hardware by any circuit, a computer CPU, memory, other LSI, etc., and in software by a program loaded into memory, etc., but here, functional blocks realized by the cooperation of these components are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various ways, such as by hardware alone or a combination of hardware and software.

[0035] The image acquisition unit 61 acquires a polarizing microscope image of the crystal (hereinafter also referred to as a “measured image”) from the polarizing microscope 1 and stores it in the storage device 70.

[0036] The defect evaluation unit 62 evaluates defects contained in the sample 2 based on the polarizing microscope image acquired by the image acquisition unit 61. The defect evaluation unit 62 compares the actual measurement image observed by the polarizing microscope 1 with the calculated image stored in the calculated image storage unit 71, determines which calculated image is similar to the actual measurement image, and acquires information about the defect corresponding to the determined calculated image. The defect evaluation unit 62 displays the acquired information about the defect on the display device 52.

[0037] The defect evaluation unit 62 may use machine-learned artificial intelligence (AI) to search for a calculated image similar to the measured image. The defect evaluation unit 62 may determine a calculated image that is highly similar to the measured image by calculating the sum of the absolute values ​​of the differences between the brightness values ​​of the measured image and the calculated image, the sum of the squares of the differences, normalized cross-correlation, or the like. Because the distribution of brightness values ​​in measured images may differ depending on measurement conditions, the defect evaluation unit 62 may normalize the brightness values ​​of the measured image before comparing it with the calculated image. The defect evaluation unit 62 may evaluate defects using an evaluator that inputs the measured image and outputs the type, size, number, orientation, etc. of defects. In this case, the crystal defect evaluation device 50 may be equipped with an AI for image search or a learning unit for machine learning the evaluator.

[0038] In order to improve the accuracy of evaluating defects from polarized light microscope images, it is desirable to calculate polarized light microscope images including defects of various types, numbers, sizes, positions, shapes, directions, and angles, and store them as calculated images in the calculated image storage unit 71.

[0039] The polarizing microscope image calculation unit 63 calculates a polarizing microscope image of the sample taking into account the shear stress distribution caused by defects in the sample, and stores the calculation result and information about the defects in association with each other in the calculated image storage unit 71. The calculated image may be acquired from another device and stored in the calculated image storage unit 71. In this case, the crystal defect evaluation device 50 does not need to include the polarizing microscope image calculation unit 63.

[0040] The polarizing microscope image calculation unit 63 may calculate the polarizing microscope image of the sample by solving a theoretical equation such as an index ellipsoid equation to determine the refractive index of polarized light propagating through a crystal to which shear stress caused by a defect has been applied. If it is impossible or difficult to analytically solve the theoretical equation, the polarizing microscope image calculation unit 63 may calculate the polarizing microscope image of the sample using a numerical analysis method such as the finite element method.

[0041] The method for calculating polarizing microscope images of SiC crystals taking into account the shear stress distribution caused by edge dislocations contained in the crystals is shown below.

[0042] SiC substrates for power devices have an off-angle of 4 degrees from the (0001) plane to the [11-20], and are optically anisotropic within the substrate plane. If the Z-axis is taken parallel to the observation direction perpendicular to the substrate, the in-plane [1-100], which is perpendicular to the off-angle, is taken as the X-axis, and the direction perpendicular to that is taken as the Y-axis, the equation for the in-plane refractive index ellipsoid is as follows: B1 0 X 2 +B2 0 Y 2 +2B6 0 XY=1 However, B1 0 =n n -2 , B2 0 =n e -2 , B6 0 =0, and n n , n e are the refractive indices for ordinary and extraordinary light, respectively.

[0043] When stress is applied to this by threading dislocations or the like, the equation of the index ellipsoid becomes as follows: B1 0 X 2 +B2 0 Y 2 +2B6 0 XY=1 However, B m =B m 0 +Π mn σ n (m=1,2,6), and Π mn , σ n are the photoelastic tensor and stress tensor expressed by the following equations, respectively.

number

[0044] Here, for simplicity, we assume that the stress due to defects is uniform in the Z direction. A method for calculating polarized light microscope images taking into account the shear stress distribution in the Z direction will be described later. The refractive index of a crystal to which stress is applied can be found as the solution to the following characteristic equation:

number

[0045] The retardation δ is proportional to the difference between these two refractive indices and can be expressed as follows:

number

[0046] Here, let us consider a case where the angle between the polarization direction of the polarizer 3 and the X axis is β, the angle between the polarization direction of the polarizer 3 and the polarization direction of the analyzer 6 is π / 2+ε, and there is a deviation β of the polarizer 3 and a deviation ε of the analyzer 6 from crossed Nicols. In this case, if the incident intensity is I0, the polarization intensity can be expressed as follows:

number

[0047] (1) When ε=0 When the deviation ε of the analyzer 6 from the crossed Nicols is 0, the polarization intensity is as follows:

number

number

number

number

[0048] Only the first term on the right-hand side causes a change in contrast, and the intensity is proportional to B6. The second term on the right-hand side causes a change in the background, σ xy The contrast is inverted by β. In the complete extinction state of β=0, B6 2 This produces a contrast proportional to the

[0049] (2) When β=0 When the deviation β of the polarization direction of the polarizer 3 from the X axis is 0, the polarization intensity is as follows:

number

number

number

[0050] The first term on the right-hand side shows a constant value regardless of stress, and the second term on the right-hand side is proportional to B6, i.e., the in-plane shear stress.

[0051] (3) When ε≠0 and β≠0 When the deviation ε of the analyzer 6 from the crossed Nicols and the deviation β of the polarization direction of the polarizer 3 from the X axis are both non-zero, the polarization intensity is as follows:

number

[0052] If the conditions assumed in the above calculations are met, it is believed that the contrast in polarization intensity calculated as above will be observed in the image observed through the polarizing microscope 1.

[0053] The polarizing microscope image calculation unit 63 sets the type, number, size, position, shape, direction, angle, etc. of defects contained in the crystal, and calculates the shear stress distribution caused in the crystal by the set defects. The polarizing microscope image calculation unit 63 calculates the polarizing microscope image as described above, taking into account the calculated shear stress distribution. The polarizing microscope image calculation unit 63 stores the calculated polarizing microscope image and information about the defects in the calculated image storage unit 71, correlating them with each other.

[0054] Next, we will explain a method for calculating polarizing microscope images that also takes into account the shear stress distribution in the Z direction. By calculating a polarizing microscope image that takes into account not only the shear stress distribution in the XY plane caused by defects but also the shear stress distribution in the Z direction, and comparing it with the actual image observed with the polarizing microscope 1, it is possible to evaluate not only the shape of the defects in the crystal in the XY direction, but also their three-dimensional shape.

[0055] The polarizing microscope image calculation unit 63 divides the crystal to be observed into multiple regions in the Z direction and calculates the propagation of polarized light as it passes through each region in stages. The number and thickness of the regions may be determined depending on the type, number, size, position, shape, direction, angle, etc. of the defects to be evaluated, the required accuracy, etc.

[0056] The polarizing microscope image calculation unit 63 may discretely calculate the change in the refractive index of polarized light inside the sample, assuming that the stress distribution in the thickness direction within each region is uniform and that birefringence occurs only at the boundaries of the regions. This allows the three-dimensional shape of the defect to be evaluated with good accuracy while reducing the calculation load. In this case, for each region, the birefringence occurring at the boundary of the region is calculated based on the shear stress distribution within the boundary surface, as explained above. First, polarized light incident on the surface of the first layer is split into ordinary light E0 and extraordinary light E1 due to birefringence. e The polarized light microscope image calculation unit 63 calculates the ordinary light E0 and the extraordinary light E when the polarized light passes through the first layer. e The retardation of the film is calculated using the formula 3. Next, the normal light E0 incident on the interface between the first and second layers is converted into the normal light E' 0,1 and extraordinary light E' e,1 The abnormal light E e is normal light E' 0,2 and extraordinary light E' e,2 The polarizing microscope image calculation unit 63 combines the light beams with the same refractive index to obtain the normal light beam E'0 (=E' 0,1 +E' 0,2 ) and anomalous light E' e (=E' e,1 +E' e,2 ) The polarized light microscope image calculation unit 63 calculates the ordinary light E'0 and the extraordinary light E' when the polarized light passes through the second layer. e The retardation of the crystal is calculated by the formula 3. The polarizing microscope image calculation unit 63 calculates the retardation accumulated in each layer by repeating the above calculation up to the last layer. The polarizing microscope image calculation unit 63 calculates the polarization intensity of the polarized light that has passed through the analyzer 6 as described above, thereby calculating a polarizing microscope image of the crystal to be observed. The polarizing microscope image calculation unit 63 stores the calculated polarizing microscope image and information about defects in the calculated image storage unit 71 in association with each other.

[0057] [Example] Polarized light images of SiC crystals were examined using a polarizing microscope 1. A 4H-SiC substrate prepared by chemical vapor deposition was used as the observation sample. The polarizing microscope 1 used was the XS-1 SiC crystal dislocation high-sensitivity visualization device manufactured by Mipox Corporation. In addition to polarized light observation, dislocations were evaluated by X-ray topography observation using synchrotron radiation. It is known that the contrast of threading edge dislocations in X-ray topography images varies depending on the direction of the Burgers vector, and by observing the same location, we investigated the correspondence between the direction of the Burgers vector of the threading edge dislocation and the contrast of the polarized light observation image.

[0058] Figure 4 shows measured polarized light observation images of threading edge dislocations with different Burgers vector directions, and a polarized light microscope image calculated under the assumption that the shear stress distribution in the Z direction is uniform as described above. The measured polarized light observation image of the edge dislocation corresponds to the calculated polarized light microscope image, and it is clear that the Burgers vector of the threading edge dislocation can be determined from the polarized light observation image. In addition, the dislocation line in the SiC substrate is

[0001] , and the Burgers vector is <0001> It is suggested that the edge component of the Burgers vector of the threading mixed dislocation can also be determined by polarized light observation. In this way, by comparing the measured polarized light observation image with the calculated polarized light microscope image, it became clear that the edge component of the threading dislocation can be determined from the polarized light observation image.

[0059] Figure 5 shows (a) a measured polarized light image of a threading edge dislocation contained in a crystal and (b) a calculated polarized light microscope image that takes into account the shear stress distribution in the Z direction due to the threading edge dislocation. The tilt direction and angle of each threading edge dislocation were determined based on the values ​​reported in a previous paper (R. Tanuma, et al. J. Appl. Phys. 124 (2018) 125703). As shown in Figure 5, the contrast intensity of the measured image changes depending on the direction of the Burgers vector, but the calculated image reproduces the same contrast intensity trend as the measured image. Furthermore, the contrast boundary of the measured image is tilted at b = 1 / 3[11-20] and 1 / 3[-1-120], but the calculated image reproduces the same direction and angle of the contrast boundary as the measured image. The above results demonstrate that the above calculation method can express changes in the polarization image depending on the inclination direction and angle of the threading dislocation, and that by comparing the calculated image with the measured image, it is possible to evaluate not only the Burgers vector of the threading dislocation but also its inclination direction and angle.

[0060] Figure 6 shows a polarized light image of a threading edge dislocation contained in a crystal. Figure 7 shows a polarized light microscope image calculated taking into account the shear stress distribution in the Z direction due to the threading edge dislocation. Here, as shown in Figure 8, the x and y coordinates of the direction vector ξ, which is a unit vector of length 1 tilted toward the dislocation line of the threading edge dislocation, are ξ1 and ξ2, respectively. That is, when the direction vector ξ is rotated by θ from

[0001] to the [11-20] direction and then by ψ around the

[0001] axis, the x and y coordinates are [ξ1,ξ2] = [sinθcosψ, sinθsinψ]. The calculated image shown in Figure 7 was calculated by changing ξ1 in increments of 0.03 in the range from 0.09 to 0.27 and changing ξ2 in increments of 0.02 in the range from -0.04 to 0.04. Comparing the measured image with the calculated image, the calculated image corresponding to ξ1 = 0.04 and ξ2 = 0.12 is most similar to the measured image. Therefore, the ξ1 and ξ2 of this threading edge dislocation can be evaluated as ξ1 = 0.04 and ξ2 = 0.12. From these ξ1 and ξ2, the inclination angles θ and ψ of this threading edge dislocation can be calculated using the above formula. The calculated image that is most similar to the measured image may be automatically determined based on normalized cross-correlation, as described above.

[0061] 9 is a flowchart showing the steps of the crystal defect evaluation method according to the embodiment. If the angle of the polarizer 3 or analyzer 6 of the polarizing microscope 1 is variable, the control device 10 adjusts the angle of the polarizer 3 or analyzer 6 according to the sample 2 (S10). If the angles of the polarizer 3 and analyzer 6 of the polarizing microscope 1 are not variable, step S10 is omitted.

[0062] The image acquisition unit 61 of the crystal defect evaluation device 50 acquires a polarizing microscope image of the crystal from the polarizing microscope 1 (S12). The defect evaluation unit 62 evaluates defects contained in the sample 2 based on the acquired polarizing microscope image (S14). The defect evaluation unit 62 outputs the evaluation result (S20).

[0063] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0064] The technique of this embodiment can also be used to evaluate defects in the crystals of semiconductor materials other than silicon carbide. [Industrial Applicability]

[0065] The present disclosure relates to a technique for evaluating defects in crystals using a polarizing microscope. [Explanation of symbols]

[0066] 1 Polarizing microscope, 2 Light source, 2 Sample, 3 Polarizer, 4 Sample stage, 5 Objective lens, 6 Analyzer, 7 Eyepiece, 8 Sample, 10 Control device, 21 Sample information acquisition unit, 22 Angle determination unit, 23 Angle adjustment unit, 31 Angle information storage unit, 50 Crystal defect evaluation device, 61 Image acquisition unit, 62 Defect evaluation unit, 63 Polarizing microscope image calculation unit, 71 Calculated image storage unit.

Claims

[Claim 1] a mounting portion for mounting a sample; a polarizer provided on the light source side of the sample; an analyzer provided on the observation side of the sample; Equipped with At least one of the polarizer and the analyzer is installed so that the polarization direction is inclined with respect to the optical principal axis of the sample, or so that the angle between the polarization direction of the analyzer and the polarization direction of the polarizer is deviated from a right angle. Polarized light microscope.

Images