Ion milling equipment and inspection system

Abstract

This ion milling device is provided with a first monitoring mechanism for measuring a quantity of sputtered particles generated by irradiating a specimen with an ion beam, and a second monitoring mechanism for capturing an image of a machined surface of the specimen formed by irradiating the specimen with the ion beam, wherein, in cross-sectional milling, if specimen sputter quantity estimated from a measurement performed by the first monitoring mechanism, and the shape of a machined surface image extracted from an image captured by the second monitoring mechanism satisfy a machining termination condition set in relation to the sputter quantity and the machined surface shape, machining of the specimen is terminated.

Description

[Technical field]

[0001] The present invention relates to an ion milling apparatus and an inspection system. [Background technology]

[0002] Ion milling equipment irradiates the surface or cross section of a sample (e.g., metal, semiconductor, glass, ceramic, etc.) with an unfocused ion beam (e.g., Ar ions) accelerated to several kV, and can obtain a smooth processed surface by flicking off atoms on the sample surface without stress through the sputtering phenomenon. This is an excellent characteristic for smoothing the surface or cross section of a sample in order to observe it using electron microscopes such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0003] Patent Document 1 discloses a method for measuring the mass of sputtered particles deposited on a quartz crystal oscillator from a change in frequency of an oscillation signal caused by the deposition of sputtered particles on a quartz crystal oscillator by milling, and estimating the thickness of a redeposition film formed by the deposition of sputtered particles on a sample. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 038650 Summary of the Invention [Problem to be solved by the invention]

[0005] Development of three-dimensional devices in which semiconductor elements are integrated three-dimensionally is underway. There are various types of three-dimensional devices, from those already in mass production to those at the development level, but examples include flash memories in which memory cell arrays are stacked, FinFETs, and GAA (Gate All Around) type FETs. These devices have fine and high aspect ratio grooves and holes densely formed, and active elements are formed by stacking insulating films, semiconductor films, or metal films on the side walls of the grooves and holes. In order to increase the yield of mass production lines for three-dimensional devices with such internal structures, it is effective to expose the internal structure of the three-dimensional device and analyze whether the desired internal structure is actually formed from SEM (Scanning Electron Microscope) images of the internal fine structure.

[0006] Cross-section milling using an ion milling apparatus that uses an unfocused ion beam has the advantage of being able to quickly expose the internal structure of a three-dimensional device, but it is difficult to perform processing with a consistent processed shape.

[0007] Fig. 6 is a schematic diagram showing how cross-section milling is performed on a sample 1. The configuration of the ion milling device will be described later with reference to Fig. 1, but a side view 50 shows the sample 1 as seen from an ion gun that irradiates an ion beam, and a top view 51 shows the sample 1 as seen from an imaging device. Note that a hole 52 is shown in the sample 1 as an example of its internal structure. Since the hole 52 is an internal structure, it cannot be seen from the outside before the cross-section milling process.

[0008] In cross-section milling, a shielding plate 3 that blocks the ion beam is placed on the sample 1, and the portion of the sample 1 that is exposed and slightly protrudes from the edge of the shielding plate 3 is milled to expose the cross-section of the sample. The intensity of the ion beam is strongest at its center (center of the ion beam) and attenuates according to a Gaussian distribution as it moves away from the center of the ion beam. As a result, the amount of sputtering is greatest in the area irradiated by the center of the ion beam, and the amount of sputtering decreases as it moves away from that point.

[0009] 6, the processed surface by the cross-section milling process is formed at an incline with respect to the depth direction (Y direction) of the hole 52. Here, since the intensity distribution of the ion beam changes depending on the distance between the ion gun and the sample, the acceleration voltage of the ion beam, the discharge voltage, the gas flow rate, etc., it is difficult to always irradiate the sample with an ion beam having the same intensity distribution. For this reason, the shape of the processed surface is likely to vary for each sample being processed.

[0010] The internal structure exposed by the cross-section milling process is captured as an SEM image (hereinafter referred to as a cross-section SEM image) from the same direction as the top view 51, and it is analyzed whether the internal structure is formed into a desired structure. Here, since the processed surface by the cross-section milling process is inclined with respect to the depth direction of the hole 52, the image of the hole 52 captured in the cross-section SEM image contains distortion caused by the inclination of the processed surface. Although this distortion can be eliminated by image processing, the degree of distortion varies depending on the shape of the processed surface. For example, the image of the hole 52a exposed by the processed surface 53 and the image of the hole 52a exposed by the processed surface 54 have different degrees of distortion. If the processed surface is obtained for each cross-section milling process, i.e., for each processed sample, and the cross-section SEM image is subjected to distortion correction according to the inclination of the processed surface, the throughput of the inspection will decrease.

[0011] In the present invention, high reproducibility of the processed shape in the cross-section milling process is achieved, thereby improving the throughput of the inspection. [Means for solving the problem]

[0012] An ion milling apparatus as one embodiment of the present invention has a sample chamber, an ion gun that emits an unfocused ion beam, a sample stage that is arranged in the sample chamber and on which the sample is placed so that a portion of the sample is exposed from an end face of a shielding plate that blocks the ion beam arranged on the sample, a first monitoring mechanism that measures the amount of sputtered particles generated when the sample is irradiated with the ion beam, a second monitoring mechanism that images the processed surface of the sample formed by irradiating the sample with the ion beam, and a control unit that terminates processing of the sample when the amount of sputtering of the sample estimated from the measurement by the first monitoring mechanism and the shape of the processed surface image extracted from the image captured by the second monitoring mechanism satisfy processing termination conditions set for the amount of sputtering and the shape of the processed surface. Effect of the Invention

[0013] The present invention provides a method for manufacturing a cross-sectional milling process using a micromachined material, comprising the steps of: forming a cross-sectional shape of a workpiece by machining the workpiece with a micromachined material; [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is an overall configuration diagram of an ion milling apparatus. [Diagram 2] FIG. 13 is a diagram showing a change in the shape of a machined surface over time. [Figure 3A] 13 is an example of a processing surface image. [Figure 3B] 13 is an example of a processed surface image. [Figure 4] 13 is a flowchart of a cross-section milling process. [Figure 5A] FIG. 1 is a schematic diagram illustrating the configuration of an inspection system. [Figure 5B] 4 is an example of image processing executed by an image processing unit. [Figure 6] FIG. 1 is a diagram for explaining a problem to be solved by the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] FIG. 1 is a diagram showing the overall configuration of an ion milling apparatus. A sample 1 is placed on a sample stage 2, and an ion beam is irradiated onto the sample 1 from an ion gun 4. The ion gun 4 employs a Penning method, which is effective for miniaturizing the structure. In a Penning method ion gun, argon ions are generated by colliding electrons generated by Penning discharge with argon gas inside the ion gun, and the generated argon ions are accelerated and emitted as an ion beam. For this reason, a discharge voltage for generating a Penning discharge and an acceleration voltage for accelerating the argon ions are applied from a high-voltage power supply 5a to the ion gun 4, and argon gas is supplied with a flow rate controlled by an MFC (Mass Flow Controller) 5b.

[0016] A shielding plate 3 is placed on the sample 1 to shield the ion beam irradiated from the ion gun 4 to the sample 1, and a portion of the sample 1 exposed so as to protrude from the end face of the shielding plate 3 is milled by the ion beam (cross-section milling). The sample stage 2 is driven by a stage driving unit 9 during the cross-section milling process. For example, the stage driving unit 9 causes the sample stage 2 to perform a swing operation about a swing axis S (Y direction) set so as to be perpendicular to the ion beam center B of the ion beam, and a slide operation along a direction (X direction) perpendicular to the ion beam center B and the swing axis S. The swing operation, which swings the sample 1 about the swing axis S within a predetermined angle range (swing angle), can smooth the processed surface. In addition, the slide operation, which moves the sample 1 back and forth in the X direction about the ion beam center B, can widen the processing width in the X direction. The milling process is performed in a sample chamber 6 evacuated by an exhaust system 10.

[0017] The ion milling apparatus is controlled by a computer 12 and a controller 11, which are sometimes collectively referred to as a control unit. The computer 12 sets the milling conditions set by the user in the controller 11, monitors the milling process (details will be described later), and changes the control values ​​of the controller 11. The controller 11 controls each component of the ion milling apparatus (the ion gun 4, the sample stage 2, the exhaust system 10, etc.) based on the set or changed control values.

[0018] The ion milling apparatus has at least two monitoring mechanisms for monitoring the cross-section milling process. The first monitoring mechanism is a sensor that estimates the amount of sputtering of the sample caused by the cross-section milling process. The first monitoring mechanism includes a quartz oscillator 17, an oscillation circuit 18, and a detection circuit 19 that are arranged near the sample 1. The quartz oscillator 17 is, for example, a disk-shaped quartz oscillator, and is desirably installed so as to be movable within the sample chamber 6 so that its position and orientation can be adjusted in order to optimize the sensitivity of the monitoring. During the milling process, the oscillation circuit 18 oscillates the quartz oscillator 17 to output an oscillation signal, and the detection circuit 19 detects the frequency of the oscillation signal. The sputter particles generated by the milling process adhere to the quartz oscillator 17, increasing the mass of the quartz oscillator, thereby changing the frequency of the oscillation signal. Using this phenomenon, the mass of the sputter particles deposited on the quartz oscillator 17 is measured from the change in the frequency of the oscillation signal. The amount of sputtering of the sample 1 caused by the milling process can be estimated from the mass of the sputter particles deposited on the quartz oscillator 17.

[0019] The second monitoring mechanism is an image sensor that monitors the processed shape by the cross-section milling process. The second monitoring mechanism includes an illumination 15 such as an LED provided outside the sample chamber 6, and an imaging device 16 that magnifies and images the processed shape of the sample 1 using an optical microscope or an electron microscope. For this purpose, an observation window 7 is provided on the upper surface of the sample chamber 6, and the processed surface formed by the cross-section milling process can be imaged by the imaging device 16 through the observation window 7. In addition, in order to prevent sputtered particles from adhering to the observation window 7, the inner surface of the observation window 7 is protected by a shutter 8. During the period when the ion beam is irradiating the sample 1, the shutter 8 is closed to prevent sputtered particles from adhering to the observation window 7. The illumination 15 illuminates the inside of the sample chamber 6, and the imaging device 16 captures images of the processed surface of the sample 1 at predetermined time intervals.

[0020] FIG. 2 is a diagram showing the change in the shape of the machined surface over time in the cross-section milling process, using images 20 captured by the imaging device 16. Note that this example is an example in which a sample without an internal structure is subjected to cross-section milling. It can be seen that the depth of the machined surface (Z direction) deepens as time passes. On the other hand, the machining depth (Y direction) cannot be grasped from an image of the machined surface captured from above. Therefore, in this embodiment, in addition to monitoring using images, monitoring of the amount of sputtering is also used. When the shape of the machined surface observed from above and the amount of sputtering match the desired values, it can be assumed that the three-dimensional machined surface formed by the cross-section milling process is the desired machined surface.

[0021] In order to automatically monitor the change in the machining surface shape observed from above as shown in FIG. 2, the obtained machining surface image is processed. FIG. 3A shows a machining surface image 30 magnified and captured by an optical microscope. The machining surface image 30 includes a cross-section milled sample image 31, a sample stage image 32, and a shielding plate image 33. The computer 12 binarizes the machining surface image 30 to obtain a machining surface image 35 shown in FIG. 3B. In addition, when binarizing, the machining surface shape is extracted taking into consideration the shadow caused by the illumination 15. When the machining surface depth 36 and the full width at half maximum (FWHM) 37 are used as representative values ​​indicating the machining surface shape for the determination of the machining surface shape described later, the machining surface depth 36 and the full width at half maximum (FWHM) 37 are measured from the machining surface image 35. The computer 12 automatically acquires the machining surface image 35 from the machining surface image 30 and measures it.

[0022] 4 shows a flow chart of the cross-section milling process in this embodiment. This flow is controlled by the computer 12.

[0023] Step 101: The user sets the milling conditions in the computer 12. The milling conditions include information on the desired machined surface shape and processing amount. Specifically, the machined surface shape and sputter amount as the processing end condition are set. There is no particular limitation on the setting method, and the machined surface image may be registered, or a representative value of the machined surface image according to the method of determining the machined surface shape implemented by the computer 12 may be registered. Regarding the sputter amount, the sputter amount of the sample to be processed may be registered, or the expected value of the sputter amount deposited on the quartz crystal oscillator 17 due to the processing of the sample may be registered. After the milling conditions are set, the ion milling device starts processing.

[0024] Steps 102-103: After continuing processing for a certain period of time, the irradiation of the ion beam from the ion gun 4 to the sample 1 is stopped, and the imaging device 16 captures an image of the sample 1 through the observation window 7 to obtain an image of the processed surface of the sample 1.

[0025] Step 104: The computer 12 extracts a machining surface pattern from the machining surface image.

[0026] Step 105: Measure the machining depth and half-width from the machining surface image. The measurement content in this step is not limited to the machining depth and half-width, depending on the machining surface shape judgment method. In addition to or instead of these two representative values, the measurement value of the machining surface image may be used.

[0027] Step 106: In parallel with the monitoring of the cross-section milling process by the second monitoring mechanism in steps 102 to 105, the first monitoring mechanism monitors the cross-section milling process during the cross-section milling process. That is, the oscillation circuit 18 oscillates the crystal oscillator 17 to output an oscillation signal, and the detection circuit 19 detects the frequency of the oscillation signal. The calculator 12 estimates the amount of sputtering of the sample 1 from a change in the frequency of the oscillation signal detected by the detection circuit 19. As a method of estimation, the amount of sputtering of the sample 1 may be estimated from the amount of sputtering accumulated on the crystal oscillator 17, or the amount of sputtering accumulated on the crystal oscillator 17 may be regarded as the amount of sputtering of the sample 1.

[0028] Step 107: If the measured machined surface shape and the measured sputter amount satisfy the machining end condition, end the machining (step 108). If the machining end condition is not satisfied, proceed to step 109. For example, if the measured machined surface shape and sputter amount are each within a predetermined error range for the machined surface shape and sputter amount that are the machining end condition set in step 101, it is determined that the machining end condition is satisfied and the machining is terminated.

[0029] Step 109: The computer 12 adjusts the swing speed and / or swing angle of the sample stage 2 as necessary. The computer 12 stores in advance the adjustment method of the swing speed and swing angle of the sample stage 2 in correspondence with the processed surface shape, and adjusts the driving method of the sample stage 2 according to the processed surface shape measured in step 105. The user acquires time-varying information of the processed surface shape and time-varying information of the sputter amount as shown in FIG. 2 under various sample stage driving conditions in advance, and sets an adjustment method for driving the sample stage 2 based on this. By storing the ideal processed surface shape and sputter amount according to the elapsed time from the start of processing, the computer 12 can estimate the deviation from the processed surface in three dimensions at that time, and adjust the driving method of the sample stage so as to, for example, further progress the processing in the Z direction (processed surface depth direction) or further progress the processing in the Y direction (processed depth direction).

[0030] In an ion milling device, the processing end condition is usually set based on the elapsed time from the start of processing, and processing ends after a predetermined period of time under the initially set milling conditions. In contrast, the ion milling device of this embodiment monitors the processed surface shape and sputter amount, and feeds them back to the milling processing conditions, thereby improving the reproducibility of three-dimensional processing of the sample.

[0031] 4 can be modified in various ways. For example, the fixed time in step 102 may be set by the user or by the device. Also, the frequency of photographing the sample may be changed according to the amount of sputtering measured in step 106.

[0032] The determination of the machining end condition for the machined surface shape is not limited to the comparison of the representative value of the machined surface shape. For example, the contour line of the machined surface image is modeled in step 105, and the computer 12 stores in advance a shape model of the contour line of the ideal machined surface shape according to the elapsed time from the start of machining, and can compare the shape model of the contour line of the ideal machined surface shape with the shape model of the contour line of the extracted machined surface image to make the determination. In addition, the computer 12 may store a learning model in which the state of the machined surface shape is machine-learned, and the learning model may be used to determine whether the machining end condition is satisfied. In this case, the measurement process in step 105 can be made unnecessary. As the learning model in this case, a learning model for determining whether the end condition is satisfied or not, or a learning model for determining the most similar machined surface shape from the time series of the machined surface shape as shown in FIG. 2, etc. can be considered.

[0033] 5A shows an inspection system using the ion milling apparatus described above. The inspection system 40 includes an ion milling apparatus 41 and an inspection apparatus 42. The inspection apparatus 42 includes a charged particle beam device 43a and a control device 43b. The ion milling apparatus 41 performs processing to expose a cross section of the sample 1, and the inspection apparatus 42 images the processed sample 1b with the charged particle beam device 43a and analyzes whether the internal structure of the sample 1 is properly formed from the cross-sectional image of the processed sample 1b.

[0034] For example, a scanning electron microscope is applied to the charged particle beam device 43a. The control device 43b is composed of a computer and can realize a predetermined function by executing a program. Here, the imaging unit 44, the image processing unit 45, and the analysis unit 46 are shown as functions related to the inspection. The imaging unit 44 controls the charged particle beam device 43a to capture a cross-sectional image of the processed sample 1b, the image processing unit 45 processes the captured cross-sectional image of the processed sample 1b, and the analysis unit 46 analyzes whether a desired internal structure is formed in the sample 1 from the cross-sectional image that has been subjected to the predetermined image processing.

[0035] An example of image processing executed by the image processing unit 45 is shown in Fig. 5B. A cross-sectional image 47 of the processed sample 1b captured by the charged particle beam device 43a shows a pattern of holes (internal structure) as shown in Fig. 6. The image of the pattern is distorted in the cross-sectional image 47 due to the inclination of the processing surface in the cross-section milling process. The image processing unit 45 binarizes the cross-sectional image 47 to extract a pattern image 48, and corrects the distortion due to the inclination of the processing surface to obtain a corrected pattern image 49.

[0036] In the inspection system of this embodiment, the variation in the three-dimensional processed surface of the processed sample 1b is suppressed within a predetermined range. Therefore, the image processing unit 45 does not need to change the correction method or correction amount of the correction pattern image 49 for each processed sample 1b, and can perform the same correction regardless of the processed sample 1b. This can improve the throughput of the inspection.

[0037] The present invention is not limited to the above-mentioned embodiment, and various modifications are included. For example, the above-mentioned embodiment has been described in detail to make the present invention easier to understand, and is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. In addition, each of the above-mentioned configurations, functions, processing units, processing means, etc. may be realized by hardware, for example, by designing them as integrated circuits. In addition, each of the above-mentioned configurations, functions, etc. may be realized by software by a processor interpreting and executing a program that realizes each function. Information such as a program, table, file, etc. that realizes each function can be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or other recording medium. [Explanation of symbols]

[0038] 1: sample, 1b: processed sample, 2: sample stage, 3: shielding plate, 4: ion gun, 5a: high voltage power supply, 5b: MFC, 6: sample chamber, 7: observation window, 8: shutter, 9: stage drive unit, 10: exhaust system, 11: controller, 12: computer, 15: lighting, 16: imaging device, 17: quartz crystal oscillator, 18: oscillation circuit, 19: detection circuit, 20: image, 30: processed surface image, 31: sample image , 32: sample stage image, 33: shielding plate image, 35: processed surface image, 36: processed surface depth, 37: half-width, 41: ion milling device, 42: inspection device, 43a: charged particle beam device, 43b: control device, 44: imaging unit, 45: image processing unit, 46: analysis unit, 47: cross-sectional image, 48: pattern image, 49: corrected pattern image, 50: side view, 51: top view, 52: hole, 53, 54: processed surface.

Claims

1. A sample chamber; an ion gun that emits an unfocused ion beam; a sample stage that is disposed within the sample chamber and on which the sample is placed so that a portion of the sample is exposed from an end face of a shielding plate that is disposed on the sample and shields the ion beam; a first monitoring mechanism for measuring an amount of sputtered particles generated by irradiating the sample with the ion beam; a second monitoring mechanism that is provided with an imaging device that is arranged outside the sample chamber and images the processed surface of the sample through an observation window provided in the sample chamber, the optical axis of the imaging device being arranged perpendicular to the center of the ion beam, and that images the processed surface of the sample that is formed by irradiating the sample with the ion beam; and a control unit that terminates processing of the sample when the amount of sputtering of the sample estimated from the measurement by the first monitoring mechanism and the shape of the processed surface image extracted from the image captured by the second monitoring mechanism satisfy processing termination conditions set for the amount of sputtering and the shape of the processed surface.

2. In claim 1, a stage driving unit that swings the sample stage at a predetermined swing angle around a swing axis perpendicular to a center of the ion beam of the ion beam; The control unit adjusts the swing speed and / or swing angle of the swing operation of the sample stage by the stage driving unit when the amount of sputtering of the sample estimated from measurement by the first monitoring mechanism and the shape of the processed surface image extracted from the image captured by the second monitoring mechanism do not satisfy the processing end condition.

3. In claim 1, the first monitoring mechanism includes a quartz crystal oscillator disposed in the sample chamber, an oscillation circuit that oscillates the quartz crystal oscillator to output an oscillation signal, and a detection circuit that detects a frequency of the oscillation signal; The control unit estimates the amount of sputtering of the sample from a mass of sputtered particles deposited on the quartz crystal oscillator, which is measured from a change in frequency of the oscillation signal.

4. In claim 1, The ion milling apparatus according to claim 1, wherein the imaging device of the second monitoring mechanism images the processed surface of the sample at predetermined time intervals.

5. In claim 1, The control unit measures a processing surface depth and a half-width of the processing surface image, and determines whether or not the processing end condition is satisfied based on the processing surface depth and the half-width of the processing surface image.

6. 1. An inspection system for inspecting a predetermined internal structure of a specimen, comprising: An ion milling apparatus according to any one of claims 1 to 5, and an inspection device for inspecting an internal structure of a processed sample processed by the ion milling device, The inspection device includes: A charged particle beam device; an imaging unit that obtains a cross-sectional image by imaging the processed surface of the processed sample using the charged particle beam device; an image processing unit that extracts a pattern image of a predetermined internal structure from the cross-sectional image, performs distortion correction on the pattern image, and outputs a corrected pattern image; an analysis unit that analyzes the correction pattern image of the predetermined internal structure output by the image processing unit, The distortion correction corrects distortion caused by inclination of the processed surface of the processed sample, and the image processing unit applies equal distortion correction to each of the pattern images extracted from a plurality of processed samples processed by the ion milling device in order to inspect the specified internal structure.

7. (delete)

8. A sample chamber; an ion gun that emits an unfocused ion beam; a sample stage that is disposed within the sample chamber and on which the sample is placed so that a portion of the sample is exposed from an end face of a shielding plate that is disposed on the sample and shields the ion beam; a first monitoring mechanism for measuring an amount of sputtered particles generated by irradiating the sample with the ion beam; a second monitoring mechanism for imaging a processed surface of the sample that is formed by irradiating the sample with the ion beam; and a control unit that terminates processing of the sample when an amount of sputtering of the sample estimated from the measurement by the first monitoring mechanism and a shape of a processed surface image extracted from an image captured by the second monitoring mechanism satisfy processing termination conditions set for the amount of sputtering and the shape of the processed surface, The control unit measures a processing surface depth and a half-width of the processing surface image, and determines whether or not the processing end condition is satisfied based on the processing surface depth and the half-width of the processing surface image.

9. 1. An inspection system for inspecting a predetermined internal structure of a specimen, comprising: An ion milling device; and an inspection device for inspecting an internal structure of a processed sample processed by the ion milling device, The ion milling apparatus includes: A sample chamber; an ion gun that emits an unfocused ion beam; a sample stage that is disposed within the sample chamber and on which the sample is placed so that a portion of the sample is exposed from an end face of a shielding plate that is disposed on the sample and shields the ion beam; a first monitoring mechanism for measuring an amount of sputtered particles generated by irradiating the sample with the ion beam; a second monitoring mechanism for imaging a processed surface of the sample that is formed by irradiating the sample with the ion beam; and a control unit that terminates processing of the sample when an amount of sputtering of the sample estimated from the measurement by the first monitoring mechanism and a shape of a processed surface image extracted from an image captured by the second monitoring mechanism satisfy processing termination conditions set for the amount of sputtering and the shape of the processed surface, The inspection device includes: A charged particle beam device; an imaging unit that obtains a cross-sectional image by imaging the processed surface of the processed sample using the charged particle beam device; an image processing unit that extracts a pattern image of a predetermined internal structure from the cross-sectional image, performs distortion correction on the pattern image, and outputs a corrected pattern image; an analysis unit that analyzes the correction pattern image of the predetermined internal structure output by the image processing unit, The distortion correction corrects distortion caused by inclination of the processed surface of the processed sample, and the image processing unit applies equal distortion correction to each of the pattern images extracted from a plurality of processed samples processed by the ion milling device in order to inspect the specified internal structure.

Images