X-ray diffraction measurement equipment and program

Abstract

To suppress deterioration of measurement accuracy.SOLUTION: An X-ray diffraction measurement device 1 comprises a bulb 20 that irradiates a sample with X-rays, and a detection sensor 28 that detects a diffraction ring of X-rays diffracted by the sample. The X-ray diffraction measurement device comprises: a setting unit 64 that sets a center position of the diffraction ring; a calculation unit 66 that calculates a distance between the sample and the detection unit based on the diffraction ring; a correction unit 68 that corrects the center position based on the distance calculated by the calculation unit 66; and a measurement unit 70 that measures information on the sample based on a correction result from the correction unit and the diffraction ring.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an X-ray diffraction measurement device and a program. [Background technology]

[0002] Conventionally, there has been known an X-ray diffraction measurement device that includes an irradiation unit that irradiates a sample with X-rays and a detection unit that detects diffraction rings of X-rays diffracted by the sample, and measures information about the sample, such as the residual stress of the sample, based on the detected diffraction rings.

[0003] When the distance between the detector and the sample changes, the center position and the radius of the diffraction ring change, resulting in a change in the residual stress value obtained as a measurement result. In other words, the distance between the detector and the sample affects the measurement accuracy of the residual stress. For this reason, for example, the X-ray diffraction measurement device described in Patent Document 1 below is configured with a laser displacement meter, and the distance is appropriately set using the laser displacement meter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-081277 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because laser displacement meters measure distance based on the laser light reflected from the sample surface, the accuracy of distance measurement can be reduced due to the influence of the color, unevenness, gloss, etc. of the sample surface, resulting in a problem of reduced accuracy in measuring information about the sample, such as residual stress.

[0006] Therefore, an object of the present invention is to provide an X-ray diffraction measurement device and a program that can suppress a decrease in measurement accuracy. [Means for solving the problem]

[0007] An X-ray diffraction measurement device according to a first aspect of the present invention is an X-ray diffraction measurement device comprising an irradiation unit that irradiates X-rays toward a sample and a detection unit that detects a diffraction ring of X-rays diffracted by the sample, and further comprising: a setting unit that sets a center position of the diffraction ring; a calculation unit that calculates a distance between the sample and the detection unit based on the diffraction ring; a correction unit that corrects the center position based on the distance calculated by the calculation unit; and a measurement unit that measures information about the sample based on the correction result by the correction unit and the diffraction ring.

[0008] An X-ray diffraction measurement apparatus according to a second aspect of the present invention includes a distance control unit that changes the actual distance by moving at least one of the sample and the detection unit, and a detection control unit that controls the detection unit to detect multiple diffraction rings according to the distance changed by the distance control unit, and the correction unit obtains a correction formula based on the correlation between the distance and the center position of the diffraction rings based on the multiple diffraction rings that the detection control unit has caused the detection unit to detect according to the distance changed by the distance control unit, and corrects the center position using the correction formula.

[0009] An X-ray diffraction measurement apparatus according to a third aspect of the present invention further includes a judgment unit that judges whether the diffraction profile peak of the diffraction ring detected by the detection unit is located within a specified range of the detection unit, and if the judgment unit judges yes, the measurement unit measures information about the sample based on the diffraction ring detected by the detection unit, and if the judgment unit judges no, the distance control unit changes the distance, and the detection control unit causes the detection unit to detect the diffraction ring again at the distance changed by the distance control unit.

[0010] A program according to a fourth aspect of the present invention causes a computer capable of communicating with an irradiation unit that irradiates X-rays toward a sample and a detection unit that detects a diffraction ring of X-rays diffracted by the sample to function as a setting unit that sets the center position of the diffraction ring, a calculation unit that calculates the distance between the sample and the detection unit based on the diffraction ring, a correction unit that corrects the center position based on the distance calculated by the calculation unit, and a measurement unit that measures information about the sample based on the correction result by the correction unit and the diffraction ring. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress a decrease in measurement accuracy. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an example of the overall configuration of an X-ray diffraction measurement apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing an example of a partial configuration of the measuring device of FIG. [Figure 3] FIG. 3 is a bottom view of the measuring device shown in FIG. 2. [Figure 4] FIG. 10 is a diagram illustrating an example of an image showing a diffraction ring detected by a detection sensor. [Figure 5] FIG. 2 is a block diagram showing an example of the hardware configuration of the computer shown in FIG. 1. [Figure 6] FIG. 2 is a block diagram showing an example of a functional configuration of a computer. [Figure 7] 10 is a flowchart showing an example of the flow of processing by a computer when calculating a correction formula for the center position. [Figure 8] 10 is a flowchart showing an example of a flow of processing by a computer when measuring residual stress. [Figure 9] 10 is a graph showing a comparison of the measurement results of residual stress according to the sample distance between when the center position is corrected and when it is not corrected. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "this embodiment") will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same elements or elements having the same functions are designated by the same reference numerals in each drawing as much as possible, and redundant description will be omitted.

[0014] <Overall structure> Fig. 1 is a diagram showing an example of the overall configuration of an X-ray diffraction measurement apparatus 1 according to this embodiment. As shown in Fig. 1, the X-ray diffraction measurement apparatus 1 includes, for example, a measurement apparatus 10, an automatic stage 12, and a computer 14. Note that Fig. 1 simplifies the illustration of the measurement apparatus 10.

[0015] The measuring device 10 is fixed to an automatic stage 12 via, for example, a fixing portion 5, etc., and the position or posture of the measuring device 10 can be controlled by the automatic stage 12.

[0016] Fig. 2 is a perspective view showing an example of a partial configuration of the measuring device 10 of Fig. 1. Fig. 3 is a bottom view of the measuring device 10 shown in Fig. 2. As shown in Figs. 2 and 3, the measuring device 10 has, for example, a tube 20, a collimator 22, a substrate 24, and a detection sensor 28. Although not shown, the measuring device 10 may also have various other components including a laser pointer for clearly indicating the X-ray irradiation position.

[0017] The tube 20 functions as an irradiation unit that generates X-rays and irradiates the generated X-rays toward a sample. Samples include measurement samples (e.g., gears, shafts, etc.) that are measurement targets for measuring information about the sample, and stress-free calibration samples (e.g., iron powder, etc.) that are used during calibration measurements. Information about the sample includes, for example, the structure and characteristics of the sample, and in this embodiment, the information about the sample is described as the residual stress of the sample.

[0018] Collimator 22 has a function of adjusting the irradiation range of X-rays from bulb 20. Collimator 22 is provided below bulb 20 (on the substrate 24 side) and extends toward substrate 24.

[0019] Detection sensor 28 is provided on one surface of substrate 24 (the surface opposite to tube 20). Detection sensor 28 includes a sensor unit that detects diffraction rings of X-rays diffracted by the sample and a circuit unit that converts the detected diffraction rings into electrical signals (pixel signals). Hereinafter, X-rays diffracted by the sample will be referred to as "diffracted X-rays." Diffraction rings are formed by diffracted X-rays and are also called Debye rings or Debye-Scherrer rings. Detection sensor 28 is an imaging element for capturing an image of the diffraction rings, and is, for example, an SOI (Silicon on Insulator) sensor in which the sensor unit and circuit unit are integrated.

[0020] On one surface of the substrate 24, the detection sensor 28 has two chips 28A and 28B arranged side by side with the collimator 22 therebetween. The collimator 22 protrudes between the two chips 28A and 28B. Also, on one surface of the substrate 24, a connector 30 and the like are provided for transmitting the electrical signal converted by the detection sensor 28 to the computer 14.

[0021] 3, rectangular central areas 36A, 36B, designated by a predetermined range (e.g., 100 pixels x 200 pixels) located in the center of each chip 28A, 28B, are indicated by imaginary dashed lines. When the diffraction profile peak of the diffraction ring is located in the central areas 36A, 36B, a sufficient range of background can be obtained on both sides of the diffraction profile peak for analysis, and a sufficient number of diffraction profiles can be obtained, thereby improving the accuracy of residual stress measurement. Note that the central areas of each chip 28A, 28B may be the centers themselves on a plane along the detection surface of each chip 28A, 28B, or may be a predetermined area including the centers or any point within the areas.

[0022] Here, the diffraction profile refers to the intensity distribution of diffracted X-rays in the radial direction based on the central coordinate of the diffraction ring. The diffraction profile peak refers to the position in the diffraction profile where the intensity of the diffracted X-rays is at its maximum. More specifically, the diffraction profile peak refers to the pixel position where the intensity of the diffracted X-rays is at its maximum among the array of pixel signals obtained from the detection sensor 28. Hereinafter, the diffraction profile peak will be referred to as the "peak position."

[0023] FIG. 4 is a diagram showing an example of an image showing a diffraction ring detected by detection sensor 28. Images 32A and 32B shown in FIG. 4 are two-dimensional distribution maps of detection values ​​by detection sensor 28. Image 32A shows diffraction ring portion C1, which is a first portion of the diffraction ring detected by chip 28A. Image 32B shows diffraction ring portion C2, which is a second portion of the diffraction ring detected by chip 28B. In this way, chips 28A and 28B detect different portions of the diffraction ring formed by the diffracted X-rays. Note that in images 32A and 32B shown in FIG. 4, only diffraction ring portions C1 and C2 are shown as band-shaped dots, but in an actually obtained image, portions other than diffraction ring portions C1 and C2 are also given a predetermined density or color corresponding to a predetermined detection value.

[0024] Here, the center position of the diffraction ring will be described. In this embodiment, the center position of the diffraction ring is the central coordinate of an arc formed when the optical axis of the irradiated X-rays smoothly connects the diffraction profile peaks (peak positions) formed on a plane along the detection surface of each chip 28A, 28B. This center position varies depending on the mounting error of each chip 28A, 28B, the distance between the sample plane and the detection sensor 28, the area of ​​the irradiated X-rays on the sample plane, the relative angle of the irradiated X-rays to the sample plane, and other factors. The center position is calculated by a predetermined center position analysis based on, for example, distortion-free diffraction ring portions C1, C2 detected by each chip 28A, 28B through calibration measurement. In the Cartesian coordinate system shown in FIG. 4, the coordinates (Rx, Ry) indicating the center position calculated based on the diffraction ring portion C1 and the coordinates (Lx, Ly) indicating the center position calculated based on the diffraction ring portion C2 do not necessarily coincide with each other, and a deviation may occur. 4 is an orthogonal coordinate system consisting of an x-axis and a y-axis, with the origin defined as the lower left point of image 32A corresponding to chip 28A on a plane along the detection surface of detection sensor 28. The x-axis corresponds to the width direction of measuring device 10 (the direction in which chips 28A and 28B are aligned), and the y-axis corresponds to the longitudinal direction of measuring device 10, which is perpendicular to the width direction.

[0025] Known techniques can be used to analyze the predetermined center position, and the following method can be used, for example. First, a temporary center position is set for the diffraction ring portions C1 and C2. Next, a diffraction profile is created at each azimuth angle α, with the temporary center position as the origin, based on images 32A and 32B of the diffraction ring portions C1 and C2. Next, the peak value of the diffraction profile is obtained as the diffraction ring radius, and the center position is calculated using the least squares method based on the diffraction ring radius. Next, the error between the calculated center position and the temporary center position is determined, and the center position that brings the error within a set range is determined as the analysis result.

[0026] Returning to Fig. 1, the automatic stage 12 is a device that adjusts its position to any desired position. The automatic stage 12 is controlled by a computer 14 and moves at least one of the sample and the measuring device 10. The automatic stage 12 has, for example, an XY stage 15, a camera length stage 16, and an illumination angle stage 17.

[0027] The XY stage 15 adjusts the position of the sample or the measuring device 10 in the XY plane along the measurement surface of the sample. The camera length stage 16 adjusts the distance between the sample and the detection sensor 28 (hereinafter referred to as "sample distance") by moving at least one of the sample and the detection sensor 28. The sample distance is, for example, the shortest distance along the length of a perpendicular line drawn from the sample to the detection sensor 28. The irradiation angle stage 17 adjusts the irradiation angle of the X-rays with respect to the measurement surface of the sample.

[0028] The computer 14 is communicatively connected to the tube 20, the detection sensor 28, and the automatic stage 12 of the measuring device 10, and controls each of the connected devices. Note that the communicative connection may be wired or wireless. The computer 14 also measures the residual stress by analyzing the diffraction ring detected by the detection sensor 28.

[0029] <Hardware configuration of computer 14> FIG. 5 is a diagram showing an example of the hardware configuration of the computer 14 of FIG.

[0030] As shown in FIG. 5, the computer 14 includes a control device 40, a communication device 46, and a storage device 48.

[0031] The control device 40 mainly comprises a CPU 42 and a memory 44. The CPU 42 controls various components of the computer 14. The memory 44 stores various programs and the like required for the computer 14 to execute processes, for example.

[0032] The communication device 46 is configured with a communication interface for communicating with an external device, etc. The communication device 46 transmits and receives various information to and from the measuring device 10, the automatic stage 12, etc.

[0033] The storage device 48 is configured by a hard disk, etc. The storage device 48 stores various programs and various information required for executing the processes in the control device 40, as well as information on the results of the processes.

[0034] The computer 14 can be realized using an information processing device such as a dedicated or general-purpose server computer. The computer 14 may be configured with a single information processing device or multiple information processing devices distributed over a communication network. Figure 5 shows only a portion of the main hardware configuration of the computer 14, and the computer 14 may also have other components that are included in a general server.

[0035] <Functional configuration of computer 14> FIG. 6 is a block diagram showing an example of the functional configuration of the computer 14. As shown in FIG.

[0036] 6, the computer 14 has, as its functional components, a control unit 50 that controls the operation of the measurement device 10, and a data processing unit 60 that measures residual stress by analyzing information about the diffraction rings detected by the detection sensor 28. Each of these functional components is realized by executing a program stored in the memory 44 or the storage device 48 under the control of the CPU 42, and operating the various hardware components of the computer 14.

[0037] The control unit 50 includes, for example, an irradiation control unit 52, a distance control unit 54, a detection control unit 56, and a determination unit 58.

[0038] The irradiation control unit 52 controls the tube 20 to output X-rays.

[0039] The distance control unit 54 changes the actual sample distance by moving at least one of the sample and the detection sensor 28. The distance control unit 54 moves at least one of the sample and the detection sensor 28 by controlling the camera length stage 16, for example.

[0040] For example, during calibration measurement, the distance control unit 54 changes the sample distance by moving at least one of the sample and the detection sensor 28 a predetermined number of times and at a predetermined movement interval. The predetermined number of movements is a number set in advance by an operator or the like as the number of times at least one of the sample and the detection sensor 28 is moved to change the sample distance. The predetermined movement interval is a distance set in advance by an operator or the like as the distance at least one of the sample and the detection sensor 28 is moved to change the sample distance.

[0041] Furthermore, during stress measurement, the distance control unit 54 changes the sample distance in accordance with the determination result by the determination unit 58. Specifically, the distance control unit 54 increases or decreases the sample distance when the determination unit 58 outputs a determination result indicating that the sample distance is inappropriate. In this case, the distance control unit 54 may increase the sample distance when the determination result indicates that the sample distance is smaller than the appropriate value, or decrease the sample distance when the determination result indicates that the sample distance is larger than the appropriate value.

[0042] The detection control unit 56 controls the detection sensor 28 to detect multiple diffraction rings according to the sample distance changed by the distance control unit 54. For example, during calibration measurement, the detection control unit 56 controls the detection sensor 28 to detect diffraction rings at the changed sample distance each time the sample distance is changed by the distance control unit 54 a predetermined number of movements and at a predetermined movement interval. The detection control unit 56 acquires information about the multiple diffraction rings detected by the detection sensor 28 from the detection sensor 28 and outputs the information to the correction unit 68.

[0043] Furthermore, when the determination unit 58 outputs a determination result indicating that the sample distance is inappropriate during stress measurement, the detection control unit 56 causes the detection sensor 28 to detect the diffraction ring again at the sample distance changed by the distance control unit 54. In other words, the detection control unit 56 causes the detection sensor 28 to detect the diffraction ring until the determination unit 58 determines that the sample distance is appropriate. When the determination unit 58 determines that the sample distance is appropriate, the detection control unit 56 acquires information about the diffraction ring detected by the detection sensor 28 in this case from the detection sensor 28 and outputs the information to the data processing unit 60.

[0044] The determination unit 58 determines whether the peak position (diffraction profile peak) of the diffraction ring detected by the detection sensor 28 is located within a designated range of the detection sensor 28. The designated range of the detection sensor 28 is a pixel range set in advance as a range appropriate for measuring residual stress, and is set to, for example, central ranges 36A and 36B (see FIG. 3). In the following description, the designated range is assumed to be the central ranges 36A and 36B.

[0045] For example, the determination unit 58 makes a first determination as to whether the peak position of the diffraction ring portion C1 is within the central range 36A, and a second determination as to whether the peak position of the diffraction ring portion C2 is within the central range 36B. For example, when the determination unit 58 judges both the first and second determinations as positive, the determination unit 58 judges that the diffraction ring is located within the designated range of the detection sensor 28 as positive, and outputs a determination result that the sample distance is appropriate to the detection control unit 56. On the other hand, when the determination unit 58 judges that at least one of the first and second determinations as negative, the determination unit 58 judges that the diffraction ring is not located within the designated range of the detection sensor 28 as negative, and outputs a determination result that the sample distance is inappropriate to the distance control unit 54. Note that the determination method by the determination unit 58 is not limited to the above. For example, the determination unit 58 may determine that the sample distance is inappropriate when both the first and second determinations are negative, and may determine that the sample distance is appropriate when at least one of the first and second determinations is positive.

[0046] Furthermore, if the determination unit 58 determines that the sample distance is inappropriate, it may further determine the relative position of the diffraction ring peak position with respect to the central ranges 36A and 36B and output the determination result to the distance control unit 54. The relative position with respect to the central ranges 36A and 36B indicates, for example, whether the peak position is located inside (toward the collimator 22) or outside (away from the collimator 22) with respect to the central ranges 36A and 36B in the width direction of the measurement device 10. If the peak positions of the diffraction ring portions C1 and C2 are located inside the central ranges 36A and 36B of the corresponding chips 28A and 28B that detected them, this indicates that the sample distance is smaller than when the peak positions are located within the central ranges 36A and 36B. If the peak positions of the diffraction ring portions C1 and C2 are located outside the central ranges 36A and 36B of the corresponding chips 28A and 28B that detected them, this indicates that the sample distance is larger than when the peak positions are located within the central ranges 36A and 36B.

[0047] For example, when both of the peak positions of the diffraction ring portion C1 and the diffraction ring portion C2 are located inside the corresponding central ranges 36A, 36B, the determination unit 58 determines that the sample distance is smaller than the appropriate value. On the other hand, when at least one of the peak positions is located outside the corresponding central ranges 36A, 36B, the determination unit 58 determines that the sample distance is greater than the appropriate value. Note that the determination method by the determination unit 58 is not limited to the above. For example, when both of the peak positions are located outside the corresponding central ranges 36A, 36B, the determination unit 58 may determine that the sample distance is greater than the appropriate value, and when at least one of the peak positions is located inside the central ranges 36A, 36B, the determination unit 58 may determine that the sample distance is smaller than the appropriate value.

[0048] The data processing unit 60 includes, for example, an image processing unit 62, a setting unit 64, a calculation unit 66, a correction unit 68, and a measurement unit .

[0049] Based on the pixel signal sequence obtained from the detection sensor 28, the image processing unit 62 generates images 32A and 32B showing the diffraction ring portions C1 and C2 detected by the detection sensor 28. The image processing unit 62 may also perform processing to combine these images 32A and 32B into a single diffraction ring image.

[0050] The setting unit 64 sets the center position of the diffraction ring detected by the detection sensor 28. The setting unit 64 sets a temporary center position indicating an arbitrary position for each of the diffraction ring portions C1 and C2 as the center position of the diffraction ring. The setting unit 64 sets, for example, the position of the central axis of the through-hole of the collimator 22 on a plane along the detection surface of each chip 28A, 28B as the temporary center position. The setting unit 64 may set different positions for the diffraction ring portions C1 and C2 as the center position of the diffraction ring, or may set them to the same position. Furthermore, when the correction unit 68 outputs the calculation results of the center positions of the diffraction ring portions C1 and C2, the setting unit 64 resets the calculation results to the temporary center positions of the diffraction ring portions C1 and C2.

[0051] The calculation unit 66 calculates the sample distance based on the diffraction ring detected by the detection sensor 28. Hereinafter, the sample distance, which is an analysis value obtained by calculation, etc., will be referred to as the "analysis sample distance." For example, the calculation unit 66 calculates the analysis sample distance for each of the diffraction ring portions C1 and C2 by analyzing the image 32A of the diffraction ring portion C1 and the image 32B of the diffraction ring portion C2 using a predetermined analysis method, based on the temporary center position set or reset by the setting unit 64. The calculation unit 66 outputs the calculation results to the correction unit 68.

[0052] The predetermined analysis method for calculating the analysis sample distance can be any known technique, for example, the following method. First, based on images 32A and 32B of diffraction ring portions C1 and C2, a diffraction profile is created at each azimuth angle α on a plane along images 32A and 32B, with the reference center position as the origin, and the peak value of the diffraction profile is taken as the diffraction ring radius. Next, based on the diffraction ring radius and the diffraction angle in a strain-free state, the analysis sample distance is calculated using a known formula. Note that the diffraction angle in a strain-free state is obtained in advance based on the strain-free diffraction ring portions C1 and C2 obtained by calibration measurement.

[0053] The correction unit 68 corrects the center position set as the tentative center position by the setting unit 64 based on the analysis sample distance calculated by the calculation unit 66. For example, the correction unit 68 obtains a correction formula based on the correlation between the sample distance and the center position of the diffraction ring, and corrects the tentative center position using the correction formula. The correction formula is, for example, a linear function that indicates the correlation between the sample distance and the center position of the diffraction ring.

[0054] The correction unit 68 obtains a correction formula based on the multiple diffraction rings detected by the detection sensor 28 by the detection control unit 56 in response to the sample distance changed by the distance control unit 54. For example, the correction unit 68 calculates the correction formula by analyzing multiple distortion-free diffraction rings obtained by changing the sample distance during calibration measurement. The correction unit 68 calculates a correction formula for each of the diffraction ring portions C1 and C2, and uses the correction formula to correct the tentative center positions of each of the diffraction ring portions C1 and C2.

[0055] The following method can be used to calculate the correction formula, for example. First, the center position is calculated based on the multiple distortion-free diffraction ring portions C1 and C2 using a predetermined center position analysis. Next, the correction unit 68 calculates the analysis sample distance by analyzing the images 32A and 32B of the multiple distortion-free diffraction ring portions C1 and C2 using the same analysis method as the calculation unit 66, using the calculated center position as a reference. Next, the analysis sample distance and center position thus calculated are plotted on the x and y axes, and the results are approximated by the linear function "y = ax + b" to calculate correction coefficients a and b, and a correction formula for the linear function is calculated.

[0056] The correction unit 68 calculates the center position of the diffraction ring by substituting the analysis sample distance calculated by the calculation unit 66 into the correction formula. If the error between the center position calculated using the correction formula and the temporary center position set or reset by the setting unit 64 is within a set range, the correction unit 68 outputs the calculated center position to the measurement unit 70 as the correction result. On the other hand, if the error is not within the set range, the correction unit 68 outputs the calculated center position to the setting unit 64.

[0057] The measurement unit 70 measures the residual stress of the sample based on the correction results from the correction unit 68 and the diffraction ring detected by the detection sensor 28. Specifically, the measurement unit 70 measures the residual stress by analyzing, using a predetermined analysis method, images 32A and 32B of diffraction ring portions C1 and C2 of the diffraction ring formed by the diffracted X-rays, with the center position output as the correction result by the correction unit 68 as a reference. Known techniques can be used as the predetermined analysis method for measuring the residual stress, and the following method can be given as an example: First, the diffraction ring radius and the analysis sample distance are acquired in the same manner as the calculation unit 66 described above. Then, the residual stress is calculated using a known formula based on the diffraction ring radius and the analysis sample distance.

[0058] <Processing flow by computer 14> Next, the flow of processing by the computer 14 will be described with reference to Figures 7 and 8. Note that the order of the following steps can be changed as appropriate.

[0059] First, the process flow for calculating the correction formula for the center position by performing calibration measurement using a stress-free calibration sample will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the process flow of the computer 14 when calculating the correction formula for the center position. The process in Fig. 7 starts after the stress-free calibration sample has been installed and an arbitrary sample distance has been set, and after measurement of environmental noise has been completed.

[0060] (Step SP10) The irradiation control unit 52 controls the tube 20 to output X-rays, and the process then proceeds to step SP12.

[0061] (Step SP12) The detection control unit 56 controls the detection sensor 28 to detect the diffraction ring portions C1 and C2. At this time, the diffraction ring portions C1 and C2 may be detected with pre-measured environmental noise and the like removed. Then, the process proceeds to step SP14.

[0062] (Step SP14) The determination unit 58 determines whether the number of times the process of step SP12 has been repeated, i.e., the number of times the diffraction ring portions C1 and C2 have been detected at different sample distances, has reached a predetermined number of movements. If the determination is negative, the process proceeds to step SP16. If the determination is positive, the process proceeds to step SP18.

[0063] (Step SP16) The distance control unit 54 changes the sample distance by moving at least one of the sample and the detection sensor 28 at predetermined movement intervals. Then, the process proceeds to step SP12.

[0064] (Step SP18) The correction unit 68 performs a predetermined center position analysis for each of the diffraction ring portions C1 and C2 detected by repeating the process of step SP12. The correction unit 68 reads images 32A and 32B of the unanalyzed diffraction ring portions C1 and C2 and repeatedly performs the center position analysis a predetermined number of times while moving the sample distance. The image processing unit 62 creates multiple images 32A and 32B used for the analysis, one for each of the diffraction ring portions C1 and C2. When the center position analysis for all of the diffraction ring portions C1 and C2 has been completed, the process proceeds to step SP20.

[0065] (Step SP20) The correction unit 68 calculates a correction equation for correcting the tentative center position based on the result of the center position analysis in the processing of step SP18. Specifically, the correction unit 68 calculates the analysis sample distance based on the images 32A and 32B of the distortion-free diffraction ring portions C1 and C2, using the center position calculated in the processing of step SP18 as a reference. Then, the correction unit 68 calculates a correction equation of a linear function based on the correlation between the calculated analysis sample distance and the center position. This completes the calculation process of the correction equation shown in FIG. 7.

[0066] Next, the processing flow of the computer 14 when measuring the residual stress of the sample to be measured will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of the processing flow of the computer 14 when measuring the residual stress. The processing in Fig. 8 starts after the measurement sample has been installed and an arbitrary sample distance has been set, and after measurement of environmental noise has been completed.

[0067] (Step SP22) The irradiation control unit 52 controls the tube 20 to output X-rays. Then, the process proceeds to step SP24.

[0068] (Step SP24) The detection control unit 56 controls the detection sensor 28 to detect the diffraction ring portions C1 and C2. At this time, the diffraction ring portions C1 and C2 may be detected with pre-measured environmental noise and the like removed. Then, the process proceeds to step SP26.

[0069] (Step SP26) The determination unit 58 determines whether the sample distance is appropriate by determining whether the peak positions of the diffraction ring portions C1 and C2 detected in the processing of step SP24 are within the corresponding central ranges 36A and 36B. If the determination is affirmative, the processing proceeds to processing of step SP30. If the determination is negative, the relative position of the peak positions with respect to the central ranges 36A and 36B is further determined to determine whether the sample distance is greater than or less than the appropriate value. Then, the processing proceeds to processing of step SP28.

[0070] (Step SP28) The distance control unit 54 controls the camera length stage 16 to change the sample distance depending on the result of the determination regarding the relative position in the processing of step SP26. If the distance control unit 54 determines that the sample distance is smaller than the appropriate value, it increases the sample distance. On the other hand, if the distance control unit 54 determines that the sample distance is larger than the appropriate value, it decreases the sample distance. Note that the distance control unit 54 may change the sample distance regardless of the result of the determination regarding the relative position. Then, the processing proceeds to the processing of step SP24.

[0071] (Step SP30) If the determination in step SP26 is affirmative, the setting section 64 sets a provisional center position for the detected diffraction ring portions C1 and C2, and then the process proceeds to step SP32.

[0072] (Step SP32) The calculation unit 66 creates diffraction profiles at each azimuth angle α, with a tentative center position as the origin, based on the images 32A and 32B of the diffraction ring portions C1 and C2 detected when the determination in step SP26 is affirmative. The tentative center position is the tentative center position set in the processing in step SP30 or reset in the processing in step SP40. The images 32A and 32B are created by the image processing unit 62 based on the information on the diffraction ring portions C1 and C2 output from the detection control unit 56 when the determination unit 58 makes a positive determination. Then, the processing proceeds to step SP34.

[0073] (Step SP34) The calculation unit 66 determines the peak value of the diffraction profile created in step SP32 as the diffraction ring radius, and calculates the analysis sample distance using a known formula based on the diffraction ring radius and the diffraction angle in a strain-free state. Then, the process proceeds to step SP36.

[0074] (Step SP36) The correction unit 68 calculates the center position by substituting the analysis sample distance calculated in the process of step SP34 into the correction formula calculated in the process of step SP20, and then the process proceeds to the process of step SP38.

[0075] (Step SP38) The correction unit 68 determines whether the error between the center position calculated in step SP36 and the tentative center position set in the processing of step SP30 or reset in step SP40 is within a set range. If the determination is negative, the process proceeds to processing of step SP40. If the determination is positive, the process proceeds to processing of step SP42.

[0076] (Step SP40) The setting section 64 resets the center position calculated in the process of step SP36 as the temporary center position, and the process then proceeds to the process of step SP32.

[0077] (Step SP42) The measurement unit 70 measures the residual stress by analyzing the images 32A and 32B of the diffraction ring portions C1 and C2 detected in the process of step SP24 using a predetermined analysis method, with the center positions calculated in the process of step SP36 as the reference. This completes the series of processes shown in FIG. 8.

[0078] <Action and effect> Next, the effects of the X-ray diffraction measurement device 1 will be explained in comparison with a conventional X-ray diffraction measurement device.

[0079] In conventional X-ray diffraction measurement equipment, residual stress is measured by analyzing the diffraction ring based on the center position calculated during calibration measurement. In this case, the center position of the diffraction ring changes when the sample distance changes, so in order to match the sample distance between calibration measurement and stress measurement, it was necessary to measure and adjust the sample distance using a laser displacement meter.

[0080] However, measurements using a laser displacement meter can be affected by the color, unevenness, or gloss of the sample surface, resulting in a decrease in the accuracy of measuring the sample distance. A change in the sample distance changes the center position of the diffraction ring, which in turn changes the residual stress obtained as a measurement result. This means that the accuracy of measuring the sample distance decreases, resulting in a decrease in the accuracy of measuring the residual stress. Another problem is that the inclusion of a laser displacement meter increases the width of the device, making it difficult to miniaturize.

[0081] In contrast, the X-ray diffraction measurement apparatus 1 according to this embodiment is an X-ray diffraction measurement apparatus 1 that includes a tube 20 that irradiates X-rays toward a sample and a detection sensor 28 that detects the diffraction ring of the diffracted X-rays, and includes a setting unit 64 that sets the center position of the diffraction ring, a calculation unit 66 that calculates an analytical sample distance, which is an analytical value of the sample distance between the sample and the detection sensor 28, based on the diffraction ring, a correction unit 68 that corrects the center position based on the analytical sample distance calculated by the calculation unit 66, and a measurement unit 70 that measures residual stress as information about the sample based on the correction result by the correction unit 68 and the diffraction ring.

[0082] With this configuration, the center position of the diffraction ring is corrected according to the analysis sample distance, and the diffraction ring is analyzed using the corrected center position as a reference, allowing residual stress to be measured. Therefore, even without adjusting the sample distance between calibration measurement and stress measurement as in the past, the center position can be corrected according to the sample distance, allowing for accurate measurement of residual stress. As a result, there is no need to use a laser displacement meter to adjust the sample distance, and a decrease in the measurement accuracy of residual stress due to a decrease in the measurement accuracy of the laser displacement meter can be suppressed. Furthermore, since there is no need to include a laser displacement meter, miniaturization can be achieved.

[0083] Fig. 9 is a graph showing the measurement results of residual stress as a function of sample distance, comparing the results with and without correction of the center position. The horizontal axis of Fig. 9 represents the sample distance (mm), and the vertical axis of Fig. 9 represents the residual stress value (MPa) obtained as a measurement result.

[0084] In the graph of Figure 9, the measurement results when the center position was corrected are indicated by squares. The measurement results when the center position was corrected are residual stress values ​​measured in the X-ray diffraction measurement device 1 according to this embodiment by analyzing the diffraction rings detected while changing the sample distance, using the center position corrected according to the analysis sample distance as a reference. In contrast, the measurement results when the center position was not corrected are indicated by circles. The measurement results when the center position was not corrected are residual stress values ​​measured in a conventional X-ray diffraction measurement device by analyzing the diffraction rings measured while changing the sample distance, using a predetermined center position that was not corrected as a reference.

[0085] As shown in Figure 9, when the center position was not corrected, the center position changed in response to changes in the sample distance, resulting in a change in the residual stress value. The greater the change in the sample distance, the greater the change in the residual stress value, which affected the accuracy of residual stress measurement. In contrast, when the center position was corrected according to the analysis sample distance, the change in the residual stress value in response to changes in sample distance was suppressed. This shows that correcting the center position can improve the accuracy of residual stress measurement.

[0086] Furthermore, the X-ray diffraction measurement apparatus 1 according to this embodiment includes a distance control unit 54 that changes the actual sample distance by moving at least one of the sample and the detection sensor 28, and a detection control unit 56 that controls the detection sensor 28 to detect multiple diffraction rings according to the sample distance changed by the distance control unit 54. The correction unit 68 obtains a correction formula based on the correlation between the sample distance and the center position of the diffraction ring, based on the multiple diffraction rings that the detection control unit 56 causes the detection sensor 28 to detect according to the sample distance changed by the distance control unit 54, and corrects the virtual center position using the correction formula.

[0087] According to this configuration, the center position is corrected using a correction formula such as a linear function based on a correlation, so geometric calculations are not required and the center position can be corrected using a simple configuration and program.

[0088] In addition, the X-ray diffraction measurement apparatus 1 according to this embodiment further includes a determination unit 58 that determines whether the peak position (diffraction profile peak) of the diffraction ring detected by the detection sensor 28 is located within a specified range of the detection sensor 28. If the determination unit 58 determines that the peak position is within a specified range of the detection sensor 28, the measurement unit 70 measures the residual stress based on the diffraction ring detected by the detection sensor 28. If the determination unit 58 determines that the peak position is within a specified range of the detection sensor 28, the distance control unit 54 changes the sample distance, and the detection control unit 56 causes the detection sensor 28 to redetect the diffraction ring at the sample distance changed by the distance control unit 54.

[0089] According to this configuration, the diffraction ring is detected at a sample distance such that the peak position of the diffraction ring is located within the specified range of the detection sensor 28. Therefore, without setting the sample distance using a laser displacement meter or the like, the diffraction ring can be detected by automatically adjusting the sample distance to be appropriate for measuring residual stress, thereby improving the accuracy of residual stress measurement. In particular, according to this embodiment, the central ranges 36A, 36B of each chip 28A, 28B are set as the specified range of the detection sensor 28, so that the background of the diffraction profile based on the diffraction ring obtained as the detection result can be sufficiently removed for analysis, thereby further improving the accuracy of residual stress measurement.

[0090] <Modification> The present invention is not limited to the above-described embodiments. In other words, variations on the above-described embodiments, which are appropriately modified by a person skilled in the art, are also included within the scope of the present invention as long as they incorporate the features of the present invention. Furthermore, the elements of the above-described embodiments and the modifications described below can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they incorporate the features of the present invention.

[0091] For example, the correction formula for correcting the center position may be stored in advance rather than being acquired by calculation by the correction unit 68. The correction unit 68 may acquire the correction formula by reading it from a memory and correct the center position using the correction formula. The correction formula is not limited to a linear function, and may be other functions. The correction unit 68 may correct the center position by analyzing the correlation between the sample distance and the center position, instead of using a correction formula.

[0092] The sample distance may be defined for each chip 28A, 28B as the shortest distance perpendicular to the sample. The distance control unit 54 may change the sample distance for each chip 28A, 28B based on the results of the first and second determinations of whether the peak positions of the diffraction ring portions C1 and C2 are within the designated ranges of the corresponding chips 28A, 28B, and the relative positions of the peak positions with respect to the designated ranges. In addition to or instead of the sample distance, the tilt of the detection sensor 28 or the sample may be changed.

[0093] Furthermore, computer 14 may include an output unit that outputs the analysis results obtained by data processing unit 60, a storage unit that stores the analysis results, an input unit that receives input from an operator, etc. Furthermore, computer 14 may perform analysis based on information such as diffracted X-ray intensity obtained from the diffraction ring detected by detection sensor 28, rather than on images 32A and 32B created by image processing unit 62. Furthermore, computer 14 may perform analysis based on a diffraction ring image obtained by combining images 32A and 32B by image processing unit 62.

[0094] In the above embodiment, an example has been described in which at least one of the sample and the detection sensor 28 is moved by the automatic stage 12, but the movement mechanism is not limited to this, and movement may also be performed by, for example, a goniometer, a robot, or the like.

[0095] Furthermore, in the above embodiment, an example was described in which the detection sensor 28 was an SOI sensor, but the detection sensor 28 may be another type of sensor, and may detect as a single diffraction ring rather than as diffraction ring portions C1 and C2.

[0096] The present invention may also be a program for causing an information processing device such as computer 14 to function as each of the functional components shown in Fig. 6. The program may be stored in a storage means disposed inside computer 14, or may be stored in an external storage means connected to X-ray diffraction measurement apparatus 1 via a network. The program may also be provided by being recorded on a computer-readable recording medium, or may be provided in a format that allows it to be installed via a network such as the Internet. [Explanation of symbols]

[0097] 1: X-ray diffraction measurement device, 20: tube (irradiation unit), 28: detection sensor (detection unit), 64: setting unit, 66: calculation unit, 68: correction unit, 70: measurement unit

Claims

1. An X-ray diffraction measurement apparatus comprising an irradiation unit that irradiates X-rays toward a sample, and a detection unit that detects diffraction rings of X-rays diffracted by the sample, a determination unit that repeats a determination as to whether or not the diffraction profile peak of the diffraction ring detected by the detection unit is located within a designated range of the detection unit until a positive determination is obtained; a distance control unit that, when a negative determination is made by the determination unit, moves at least one of the sample and the detection unit to change the distance between the sample and the detection unit for the next detection by the detection unit; a setting unit that sets the center position of the diffraction ring detected when the determination unit makes a positive determination; a calculation unit that calculates an analytical value of the distance by analyzing the diffraction ring; a correction unit that corrects the center position based on the analytical value calculated by the calculation unit; a measurement unit that measures information about the sample based on the correction result by the correction unit and the diffraction ring; An X-ray diffraction measurement apparatus comprising:

2. The correction unit obtains a correction formula based on the correlation between the distance and the center position of the diffraction ring, and corrects the center position using the correction formula.

2. The X-ray diffraction measurement apparatus according to claim 1.

3. An irradiation unit that irradiates a sample with X-rays, a detection unit that detects diffraction rings of X-rays diffracted by the sample, and a computer that can communicate with each other, a determination unit that repeats a determination as to whether or not the diffraction profile peak of the diffraction ring detected by the detection unit is located within a designated range of the detection unit until a positive determination is obtained; a distance control unit that, when a negative determination is made by the determination unit, moves at least one of the sample and the detection unit to change the distance between the sample and the detection unit for the next detection by the detection unit; a setting unit that sets the center position of the diffraction ring detected when the determination unit makes a positive determination; a calculation unit that calculates an analytical value of the distance by analyzing the diffraction ring; a correction unit that corrects the center position based on the analytical value calculated by the calculation unit; a measurement unit that measures information about the sample based on the correction result by the correction unit and the diffraction ring; A program to function as a

4. The correction unit obtains a correction formula based on the correlation between the distance and the center position of the diffraction ring, and corrects the center position using the correction formula.

4. The program according to claim 3.

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