JP6164065B2 - Stress evaluation method and stress evaluation apparatus - Google Patents

Description

  The present invention relates to a stress evaluation method and a stress evaluation apparatus.

  A semiconductor device manufactured using various types of materials such as a semiconductor material, an insulating material, and a metal material has a complicated strain distribution due to a difference in coefficient of thermal expansion between the materials and disorder of atomic arrangement. This strain distribution has a great influence on the electrical characteristics of the semiconductor device.

  Strain that is inevitably introduced in a manufacturing process or the like may cause performance degradation of a semiconductor device. On the other hand, distortion may be actively introduced into a predetermined region of the semiconductor device to improve the electrical characteristics of the semiconductor device.

  From these facts, quantitative evaluation of the strain or the stress causing the strain is important for manufacturing a high-performance semiconductor device.

  The distortion of a minute region of a semiconductor device can be measured by an X-ray diffraction method, a Raman spectroscopy method, an electron diffraction method, or the like. X-ray diffraction and Raman spectroscopy can measure average strain on the order of submicrons. However, since these methods have a large probe diameter, it is difficult to apply them to measurement of local strain on the nanometer order.

  Electron diffraction is used to measure local strain on the nanometer order. Electron diffraction methods include a method of measuring the amount of change in lattice constant from the amount of movement of an electron diffraction spot or HOLZ (High-order Laue zone) line, and the split width of a HOLZ line or ZOLZ (Zeroth-order Laue zone) figure. There is a method of measuring the amount of curvature of a sample from the amount of change in the geometric pattern.

  Hereinafter, a geometric pattern of a ZOLZ figure is referred to as a ZOLZ pattern. Also, the method of measuring the change amount of the lattice constant from the amount of movement of the electron diffraction spot or the HOLZ line is called the first method, and the amount of bending of the sample is measured from the change amount of the split width of the HOLZ line or the geometric pattern of the ZOLZ. The method is called the second method.

  The first method is effective when the measurement region is symmetrically sandwiched between strain sources and the crystal lattice is uniformly distorted. However, with this method, when the strain source is only on one side of the measurement region and the distortion of the crystal lattice is not uniform, the amount of strain cannot be measured with high accuracy. For this reason, it is difficult to use the first method for evaluating distortion introduced into a semiconductor device.

  On the other hand, the second method is effective even when it is affected by distortion from one side of the measurement region, and is used for evaluating distortion introduced into the semiconductor device.

JP 2001-27619 A JP 2007-93344 A JP 2009-2748 A

  An object of the present invention is to provide a stress evaluation method and a stress evaluation apparatus that can highly accurately evaluate a stress that causes distortion in a semiconductor device or other structure.

  According to one aspect of the disclosed technology, a first step of polishing or grinding a structure to form an end face, measuring a surface displacement of the end face to obtain a surface displacement image, and the structure on the end face A second step of acquiring a structural image for discriminating the contour of each of the constituent elements, and a plurality of the surface displacement images obtained by repeatedly performing the first step and the second step. A step of generating a three-dimensional elastic deformation image and generating a structure model by three-dimensionally reconstructing the plurality of structure images; and an evaluation region by virtually applying stress to a predetermined position of the structure model A stress evaluation method comprising: calculating an elastic deformation distribution of the image and searching for a stress value as a solution by changing the stress so that the calculation result matches the elastic deformation distribution obtained from the three-dimensional elastic deformation image Is provided.

  According to another aspect of the disclosed technology, a storage unit that stores a data set of surface displacement images at a plurality of end faces of a structure, a data set of structure images of each end face, and a data set of the surface displacement images 3D is reconstructed to generate a 3D elastic deformation image, the structural image data set is 3D reconstructed to generate a structural model, and stress is virtually applied to a predetermined position of the structural model. And a control unit for calculating an elastic deformation distribution in the evaluation region.

  According to the stress evaluation method and the stress evaluation apparatus according to the above aspect, the stress that causes the distortion in the semiconductor device or other structure can be evaluated with high accuracy.

FIG. 1A is a cross-sectional topography image of a transistor without a strain source, and FIG. 1B is a cross-sectional topography image of a transistor with a strain source. 2A is a diagram in which the finite element method is applied to the cross-sectional topography image in FIG. 1A, and FIG. 2B is a diagram in which the finite element method is applied to the cross-sectional topography image in FIG. FIG. FIG. 3 is a conceptual diagram for explaining the stress evaluation method according to the embodiment. FIG. 4 is a flowchart illustrating the stress evaluation method according to the embodiment. FIG. 5 is a diagram illustrating an example of the FEM structural model. FIG. 6 is a diagram illustrating an example of an elastic deformation distribution when the (100) plane of the evaluation sample is exposed.

  Hereinafter, before describing the embodiment, a preliminary matter for facilitating understanding of the embodiment will be described.

  As described above, the second method for measuring the amount of curvature of the sample from the split width of the HOLZ line and the amount of change in the ZOLZ pattern is effective even when it is affected by distortion from one side of the measurement region. It is used to evaluate distortion introduced into the device. However, this second method also has the following problems.

  That is, the second method cannot be applied to a structure of 100 nm or less in which a HOLZ line or a ZOLZ pattern does not physically appear or a thick sample of 1 μm or more in which an electron beam is not transmitted. In addition, since the split of the HOLZ line and the change of the ZOLZ pattern are premised on the uniform curvature of the crystal lattice, the second method cannot be applied to a complicated structure where the uniform curvature of the crystal lattice cannot be expected. . Furthermore, since the HOLZ line and the ZOLZ pattern are caused by crystallinity, the second method cannot be applied to amorphous.

  For these reasons, when the structure of a semiconductor device is complicated, conventionally, only a crystal region that can be regarded as single along the transmission direction of the electron beam is locally cut out as an evaluation sample. However, this cannot accurately evaluate distortion in a desired region of the semiconductor device.

  In the following embodiments, a stress evaluation method and a stress evaluation apparatus that can accurately evaluate a stress that causes distortion in a semiconductor device or other structure will be described.

(Embodiment)
FIG. 1A is a cross-sectional topography image of a transistor without a strain source, and FIG. 1B is a cross-sectional topography image of a transistor with a strain source. 2A is a diagram in which a finite element method (FEM) is applied to the cross-sectional topography image of FIG. 1A, and FIG. 2B is a cross-sectional topography of FIG. It is the figure which applied the finite element method with respect to the image.

  As can be seen from FIGS. 1A and 1B, the silicon substrate has a flat cross section when there is no strain source, whereas silicon has a silicide (CoSix) serving as a strain source on the surface of the silicon substrate. Swelling is observed on the cross section of the substrate.

  When these states are reproduced and calculated by the finite element method, it can be seen that the surface of the silicon substrate is pulled by the strain source, as shown in FIGS.

  This type of strain usually exists as internal stress and does not surface. However, when a semiconductor device is subjected to processing such as polishing or grinding (hereinafter also simply referred to as “polishing”) to bring out a new surface, the latent stress is released and appears as a change in surface displacement. This change in surface displacement is acquired using a scanning probe microscope (SPM) or a scanning laser displacement meter, and used as a surface displacement image (first step).

  Hereinafter, the surface that appears on the surface by polishing the sample is referred to as an end surface. Moreover, the process of forming a new end face is called an end face forming process.

In the step of acquiring the surface displacement image, it is preferable to use a scanning probe microscope and a laser displacement meter separately according to the area of the evaluation region. For example, a scanning probe microscope is used if the evaluation area is several μm ² or less, and a scanning laser displacement meter is used if the evaluation area is more than that. When using a scanning probe microscope, the probe may be in contact with the sample or non-contact.

On the other hand, in the end face forming step, a focused ion beam (FIB) method, a mechanical polishing method, a CMP (Chemical Mechanical Polishing) method, or the like is used. These methods may be properly used according to the processing area. For example, if the processing area is several μm ² or less, the focused ion beam method is used, and if it is more than that, the mechanical polishing method or the CMP method is used.

  The direction of polishing is not limited to orientations such as [100] and [110], and may be arbitrary. The polishing amount may be determined according to the minimum structure size in the evaluation region. For example, when evaluating the stress distribution around the transistor of the semiconductor device, it is preferable to set the polishing amount with reference to 1/10 of the gate length and gate width.

  In the present embodiment, a surface displacement image data set (surface displacement image data of each end surface) is obtained by alternately and repeatedly performing the end surface forming step and the step of acquiring the surface displacement image. Then, a three-dimensional elastic deformation image (stress relaxation image) is obtained by three-dimensionally reconstructing the surface displacement image data set. The method for three-dimensional reconstruction of the surface displacement image data set is arbitrary, but surface rendering capable of displaying an image on a specified cut surface is recommended.

  On the other hand, when acquiring a surface displacement image, a structure image different from the surface displacement image data set is obtained by taking an image (hereinafter referred to as “structural image”) for determining the contour of each component. (2nd process) is acquired.

  A scanning probe microscope may be used for photographing the structure image, and a scanning electron microscope (SEM), a scanning laser microscope, an optical microscope, or the like may be used. When using a scanning probe microscope, an image obtained by removing a height component from a surface displacement image is used. By reconstructing the structural image data set three-dimensionally, a structural model for applying the finite element method (hereinafter referred to as “FEM structural model”) is obtained.

  A structural image may be generated from a three-dimensional CAD (Computer Aided Design) diagram. However, in order to improve the accuracy of stress calculation, it is preferable to use an actually captured end face image as the structural image.

  For the FEM structural model constructed in this way, a component that may be a strain source is specified, and a stress is virtually applied to the component, so that the evaluation region when the stress is applied Displacement can be calculated. Then, the calculation result is collated with the displacement of the evaluation region obtained from the three-dimensional elastic deformation image, and the stress applied to the component is changed until the calculation result coincides with the displacement of the evaluation region obtained from the three-dimensional elastic deformation image. Repeat the calculation of the displacement of the evaluation area.

  Hereinafter, the displacement of the evaluation region calculated using the FEM structural model is referred to as a calculated value of the elastic deformation distribution, and the displacement of the evaluation region obtained from the three-dimensional elastic deformation image is referred to as an actually measured value of the elastic deformation distribution.

  For example, the structure calculation is performed by changing the stress X applied to the contact material portion of the semiconductor device and the stress Y applied to the wiring material portion by a minute amount (ΔX, ΔY), respectively, and the elastic deformation distribution in the evaluation region is calculated. Then, the calculated values of the elastic deformation distribution and the measured values are collated, and the stresses X and Y that minimize the difference between them are searched. The searched X and Y can be regarded as stress actually applied to the contact material portion and the wiring material portion, that is, a solution.

  Collation between the calculated value of the elastic deformation distribution and the actual measurement value is performed using a surface displacement image at an arbitrary cut surface (evaluation region) extracted from the three-dimensional elastic deformation image. The matching algorithm may be any algorithm that minimizes the difference between the calculated value of the elastic deformation distribution and the actual measurement value, and is not limited to a specific algorithm.

  For example, the SIMPLEX method is used when evaluating only the difference at the end face perpendicular to a certain normal line, and the genetic algorithm is used when evaluating the difference at the end face perpendicular to a plurality of normal lines. To do. A single-purpose numerical optimization algorithm may be used for the former, and a multi-purpose numerical optimization algorithm for the latter.

  In this way, the elastic deformation distribution of an arbitrary cut surface (evaluation region) and the value of stress applied to the strain source can be obtained.

  Hereinafter, the stress evaluation method according to the present embodiment will be described in more detail with reference to the conceptual diagram of FIG.

  In the stress evaluation method according to the present embodiment, a focused ion beam device (FIB) 12, a scanning probe microscope (SPM) 13, and a scanning electron microscope (SEM) 14 are provided. use.

  Here, for convenience of explanation, the focused ion beam device 12, the scanning probe microscope 13, and the scanning electron microscope 14 are all controlled by the control device 15. Both the surface displacement image data acquired by the scanning probe microscope 13 and the structure image data acquired by the scanning electron microscope 14 are sent to the stress evaluation device 16 via the control device 15.

  The stress evaluation device 16 includes a computer and includes a calculation unit 16a and a storage unit 16b. Each time a new end face is formed by the focused ion beam device 12, the stress evaluation device 16 accumulates the surface displacement image data and the structure image data in the storage unit 16b. A structural image data set is obtained. Then, the calculation unit 16a of the stress evaluation device 16 generates a three-dimensional elastic deformation image by three-dimensionally constructing the surface displacement image data set, and generates a FEM structural model by three-dimensionally constructing the structural image data set. .

  Thereafter, the calculation unit 16a of the stress evaluation device 16 searches for the stress applied to the evaluation region using the three-dimensional elastic deformation image and the FEM structural model. The search result of the stress is displayed on the display unit 17. In addition, a three-dimensional elastic deformation image, an FEM structural model, and the like generated by the calculation unit 16a of the stress evaluation device 16 are also appropriately displayed on the display unit 17.

  Note that reference numeral 20 in FIG. 3 indicates an evaluation sample, and reference numeral 11 indicates a stage on which the evaluation sample 20 is mounted.

  FIG. 4 is a flowchart showing the stress evaluation method according to the present embodiment.

  First, in step S <b> 11, an end face forming process is performed on the evaluation sample 20 using the focused ion beam device 12 to form an end face.

  Next, the process proceeds to step S <b> 12, and a structural image of the end face of the evaluation sample 20 is taken by the scanning electron microscope 14. The data of the structure image photographed by the scanning electron microscope 14 is sent to the stress evaluation device 16 via the control device 15 and accumulated in the storage unit 16b.

  Next, the process proceeds to step S13, and a surface displacement image of the end face is acquired using the scanning probe microscope 13. Data of the surface displacement image acquired by the scanning probe microscope 13 is also sent to the stress evaluation device 16 via the control device 15 and accumulated in the storage unit 16b.

  Next, the process proceeds to step S14, and it is determined whether additional polishing is necessary. For example, if the polishing has not been completed to the preset depth, or if the preset number of times of polishing has not been completed, it is determined that additional polishing is necessary (YES), and the process proceeds to step S15. On the other hand, when the polishing is completed to a preset depth or when the preset number of times of polishing is completed, it is determined that no additional polishing is necessary (NO), and the process proceeds to step S16.

  When the process proceeds from step S14 to step S15, an additional polishing amount is set. The additional polishing amount may be constant or may be changed according to the structure of the evaluation sample 20 (size of each part, material, etc.).

  After the additional polishing amount is set in step S15, the process returns to step S11. Then, the evaluation sample 20 is polished by the polishing amount set in step S15 to form a new end face. Thereafter, a structural image is taken in step S12, and a surface displacement image is acquired in step S13.

  In this manner, the structure image data and the surface displacement image data are accumulated in the storage unit 16b of the stress evaluation device 16.

  If it is determined in step S14 that no additional polishing is necessary, the process proceeds to step S16. In step S16, the calculation unit 16a of the stress evaluation device 16 reads the structural image data set and the surface displacement image data set stored in the storage unit 16b. Then, the arithmetic unit 16a three-dimensionally reconstructs the structural image data set to generate a three-dimensional elastic deformation image, and three-dimensionally reconstructs the surface displacement image data set to generate an FEM structural model. An example of the FEM structural model is shown in FIG.

  Next, the process proceeds to step S17. In step S <b> 17, a stress that is virtually applied to a component that is a strain source is set (input) in the stress evaluation device 16. The designation of the component to which the stress is applied may be arbitrary, and the stress value (initial value) to be set may be arbitrary.

  Thereafter, the process proceeds to step S18, and the calculation unit 16a of the stress evaluation device 16 calculates the elastic deformation distribution in the evaluation region using the FEM structural model. Here, before the next step, a cut surface to be an evaluation region is determined, and the cut surface is set to be a free end (exposed surface). By doing so, the elastic deformation distribution in the cut surface can be calculated. The cut surface does not need to be along a specific direction and can be set arbitrarily.

  FIG. 6 is a diagram illustrating an example of an elastic deformation distribution when the (100) plane of the evaluation sample 20 is exposed. FIG. 6 shows an elastic deformation distribution when a stress of 1.6 GPa is applied to a portion (contact material portion) indicated by an arrow in the drawing.

  Next, the process proceeds to step S19, and the calculation unit 16a of the stress evaluation device 16 collates the calculated value of the elastic deformation distribution on the cut surface with the actually measured value of the elastic deformation distribution obtained from the three-dimensional elastic deformation image. In this collation step, for example, the difference (mean square error) between the calculated value and the actually measured value is calculated for each pixel. Further, image similarity may be calculated using a normalized mutual function or the like.

  Next, the process proceeds to step S20. In step S20, it is determined whether or not collation is performed on another cut surface. If collation is performed on another cut surface, the process returns to step S18. If collation is not performed on another cut surface, the process proceeds to step S21.

  In addition, the number of cut surfaces to collate is arbitrary. In addition, results such as differences and similarities relating to collation may be classified for each cut surface, and a collation index (objective function) may be unified as the sum of cut surfaces.

  When it determines with not collating with another cut surface by step S20, it transfers to step S21. In step S <b> 21, the calculation unit 16 a of the stress evaluation device 16 determines the degree of coincidence between the calculated value of the elastic deformation distribution and the actual measurement value on each cut surface (evaluation region).

When the mean square error is used for matching, the closer to zero, the higher the degree of matching. When using similarity, the larger the value (the closer to 1 in the case of a correlation coefficient), the higher the degree of matching. It can be said. The threshold value of the degree of coincidence can be arbitrarily set. For example, if the amount of change in the degree of coincidence converges to 10 ⁻⁵ (0.001%) or less, it can be regarded as coincidence.

  If it is determined in step S21 that the calculated value of the elastic deformation distribution matches the actual measurement value (YES), the process proceeds to step S22. If it is determined that they do not match (NO), the process proceeds to step S17.

  When shifting from step S21 to step S17, the stress value input to the strain source is changed. When collation is performed on a plurality of cut surfaces, the stress value to be input next is set so that the degree of coincidence is high on all cut surfaces. If the sum of all cut surfaces is used, the stress value to be input next is set so that the value approaches zero.

  When the stress value to be input next is determined, a multi-objective numerical optimization algorithm such as a genetic algorithm or a single-objective numerical optimization algorithm such as the SIMPLEX method is used.

  In addition, in the process (loop) from step S17 to step S21, when the number of components to which stress is applied is large, it may take time to converge the coincidence. In that case, for example, two greatly different stress values such as 10 and -10 or 10 and 100 are given to each component, and the contribution of the change in the coincidence is analyzed. As a result, it can be seen which component gives more change to the degree of coincidence. Therefore, if a component with a small change (contribution is small) is deleted, calculation efficiency can be improved. Similarly, when the stress value of a certain component becomes constant in the process of calculating the degree of coincidence, the calculation can be made more efficient by excluding that component as a constant.

  If it is determined in step S21 that the calculated value of the elastic deformation distribution matches the actual measurement value, the stress value at that time can be regarded as a stress value actually applied to the strain source, that is, a solution. In this case, the process proceeds from step S21 to step S22. In step S <b> 22, the stress evaluation device 16 displays, for example, the stress value of each component and the degree of coincidence between the calculated value and the actually measured value on the display unit 17.

  As described above, in the stress evaluation method according to the present embodiment, the end surface formation step and the surface displacement image acquisition step are repeatedly performed on the evaluation sample 20 to generate a three-dimensional elastic deformation image, and the structure image at each end surface is obtained. Acquire and generate FEM structural model. Then, a stress is virtually applied to the component of the evaluation sample to calculate the elastic deformation distribution in the evaluation region, and the stress actually applied to the component is searched.

  Thus, in the stress evaluation method according to the present embodiment, stress that causes distortion in the structure is evaluated by a method different from the conventional electron diffraction method. For this reason, the stress evaluation method according to the present embodiment is applied to a thin structure of 100 nm or less, which is difficult with an electron diffraction method, a thick sample of 1 μm or more that does not transmit an electron beam, and an amorphous material that does not have crystallinity. Can be applied.

  In the stress evaluation method according to the present embodiment, only the physical property is necessary for quantifying the strain. For this reason, the stress evaluation method according to the present embodiment is less restricted than the Raman spectroscopy method and the ZOLZ method that require a database, and can be applied to the evaluation of stress that causes distortion in various semiconductor devices. Then, by feeding back the evaluation results to the design stage, the characteristics and reliability of the semiconductor device can be further improved.

  The stress evaluation method disclosed in the embodiment does not depend on the structure, thickness, crystallinity, or the like of the sample, and can be applied to the evaluation of stress in various structures as well as semiconductor devices.

  The following additional notes are disclosed with respect to the above embodiments.

(Appendix 1) A first step of polishing or grinding a structure to form an end surface, measuring a surface displacement of the end surface, and obtaining a surface displacement image;
A second step of obtaining a structural image for determining a contour of a component of the structure on the end surface;
A plurality of surface displacement images obtained by repeatedly performing the first step and the second step are three-dimensionally reconstructed to generate a three-dimensional elastic deformation image, and the plurality of structure images are three-dimensionally reconstructed. Building and generating a structural model;
A stress is virtually applied to a predetermined position of the structural model to calculate an elastic deformation distribution in the evaluation region, and the stress is applied so that the calculation result matches the elastic deformation distribution obtained from the three-dimensional elastic deformation image. And a step of searching for a stress value that is changed to be a solution.

  (Additional remark 2) The stress evaluation method of Additional remark 1 characterized by acquiring the said surface displacement image with either a scanning probe microscope or a scanning laser displacement meter.

  (Supplementary note 3) The stress evaluation method according to supplementary note 1 or 2, wherein the structural image is acquired by any one of a scanning probe microscope, a scanning electron microscope, a scanning laser microscope, and an optical microscope.

  (Additional remark 4) The said structural image is produced | generated from the CAD (Computer Aided Design) figure of the said structure, The stress evaluation method of Additional remark 1 or 2 characterized by the above-mentioned.

  (Supplementary Note 5) In the step of searching for the stress value, the degree of coincidence between the elastic deformation distribution in the evaluation region calculated from the structural model using the SIMPLEX method or a genetic algorithm and the elastic deformation distribution obtained from the three-dimensional deformation image The stress evaluation method according to any one of appendices 1 to 4, wherein the stress is calculated.

  (Supplementary note 6) In the step of searching for the stress value, a plurality of the evaluation regions are set, and an elastic deformation distribution is calculated in each evaluation region, The stress evaluation according to any one of supplementary notes 1 to 5, Method.

  (Appendix 7) The stress evaluation method according to any one of appendices 1 to 6, wherein the structure is a semiconductor device.

(Supplementary Note 8) A storage unit that stores a data set of surface displacement images on a plurality of end faces of a structure and a data set of structure images on each end face;
The surface displacement image data set is three-dimensionally reconstructed to generate a three-dimensional elastic deformation image, the structural image data set is three-dimensionally reconstructed to generate a structural model, and the structural model is placed at a predetermined position in the structural model. And a control unit that calculates the elastic deformation distribution in the evaluation region by applying stress virtually.

  (Additional remark 9) The said control part changes the said stress so that the elastic deformation distribution of the said evaluation area | region in the said evaluation area may correspond with the elastic deformation distribution of the said evaluation area | region obtained from the said three-dimensional elastic deformation image. The stress evaluation apparatus according to appendix 8, wherein the elastic deformation distribution is calculated.

  DESCRIPTION OF SYMBOLS 11 ... Stage, 12 ... Focused ion beam apparatus, 13 ... Scanning probe microscope, 14 ... Scanning electron microscope, 15 ... Control apparatus, 16 ... Stress evaluation apparatus, 16a ... Calculation part, 16b ... Memory | storage part, 17 ... Display, 20 ... Evaluation sample.

Claims (5)

Polishing or grinding the structure to form an end face, measuring a surface displacement of the end face to obtain a surface displacement image;
A second step of obtaining a structural image for determining a contour of a component of the structure on the end surface;
A plurality of surface displacement images obtained by repeatedly performing the first step and the second step are three-dimensionally reconstructed to generate a three-dimensional elastic deformation image, and the plurality of structure images are three-dimensionally reconstructed. Building and generating a structural model;
A stress is virtually applied to a predetermined position of the structural model to calculate an elastic deformation distribution in the evaluation region, and the stress is applied so that the calculation result matches the elastic deformation distribution obtained from the three-dimensional elastic deformation image. And a step of searching for a stress value that is changed to be a solution.   The stress evaluation method according to claim 1, wherein the surface displacement image is acquired by one of a scanning probe microscope and a scanning laser displacement meter.   The stress evaluation method according to claim 1, wherein the structural image is acquired by any one of a scanning probe microscope, a scanning electron microscope, a scanning laser microscope, and an optical microscope.   The stress evaluation method according to any one of claims 1 to 3, wherein in the step of searching for the stress value, a plurality of the evaluation regions are set, and an elastic deformation distribution is calculated in each evaluation region. A storage unit for storing a data set of surface displacement images at a plurality of end faces of the structure, and a data set of structure images of each end face;
The surface displacement image data set is three-dimensionally reconstructed to generate a three-dimensional elastic deformation image, the structural image data set is three-dimensionally reconstructed to generate a structural model, and the structural model is placed at a predetermined position in the structural model. And a control unit that calculates the elastic deformation distribution in the evaluation region by applying stress virtually.

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