JP2012103015A - Evaluation method and evaluation device of semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately define coordinates of respective spots in a nano electron beam diffraction pattern to calculate a lattice plane distance with sufficient accuracy.SOLUTION: The above object is attained by an evaluation method of a semiconductor element in which a computer executes steps of: generating data converted into black and white by converting an electron ray or X-ray diffraction pattern showing a plurality of spots including a diffraction spot and a penetration spot; creating a definition circle equivalent to areas of the spots using the data converted into black and white; acquiring an approximation circle of the spots by changing at least one of size or coordinates of the definition circle so that the square sum of difference in the respective pixels of the spots and the definition circle is minimized to be fit to the spots; and calculating a distance between the spots to acquire a lattice plane distance by defining the coordinates of the spots at center coordinates of the approximation circle.

Description

  The present invention relates to a semiconductor element evaluation method and an evaluation apparatus.

  Along with the miniaturization of LSI, a technique for improving the performance of the element without depending on the scaling is required. For example, one mechanism is a mechanism that accelerates the movement of holes and electrons by applying compression or tensile stress in the carrier traveling direction of the channel portion of the field effect transistor. It is very important to quantitatively evaluate how much such intentionally applied stress is actually. Further, it is very important to experimentally evaluate the relationship between the stress distribution and the device structure in order to optimize the device manufacturing process. Even if the strain is not intentionally applied, an intrinsic strain is often applied to the heterogeneous junction (hetero) interface due to the difference in the coefficient of thermal expansion between the materials. It is often the cause.

  In this way, the means that can measure a strain-applied device with nanometer-order resolution include nano-beam diffraction (NBD) based on a transmission electron microscope (TEM) and focused electron diffraction. (Convergent-Beam Electron Diffraction: CBED) only. In particular, NBD is slightly less sensitive to strain than CBED, but it can relatively easily analyze strain in a smaller area (analysis can be performed in the same procedure as limited-field electron diffraction). Compared with the large scattering cross section, it can be applied to thin samples (high resolution in the thickness direction), and the probe can be incident perpendicularly to the device, resulting in high lateral resolution. It is suitable for evaluating lattice strain at the manufacturing site. Both NBD and CBED estimate the amount of strain from the amount of displacement of the lattice plane distance.

In NBD and limited-field electron diffraction, the fact that the lattice spacing d is proportional to the inverse of the distance R between the diffraction spot and the transmission spot (Direct spot) (d spot1 / R) is used. (Approximate expression of d = Lλ / R is used. L is the camera length, λ is the electron wavelength) That is, to accurately measure the distance R between the diffraction spot and the transmission spot is to accurately measure the lattice plane distance. It directly affects the quantitative accuracy of distortion. When obtaining the distortion amount using NBD, it is common to obtain the distortion amount R _dis by the following formula from 1 / R ₀ obtained in the undistorted region and 1 / R obtained in the strain measurement location. .

  In limited-field electron diffraction, an electron beam parallel pattern is irradiated to obtain an electron diffraction pattern image, and each diffraction spot measured has a Gaussian distribution. However, the bottom of the Gaussian distribution is distorted due to the influence of the region made amorphous by FIB (Focused Ion Beam) damage on the front and back surfaces of the sample. For this reason, a profile of an electron beam diffraction pattern image is extracted, and fitting is performed assuming that the diffraction spots have a Gaussian distribution, thereby correctly measuring the distance between the diffraction spots without arbitraryness.

  On the other hand, in NBD, a parallel beam is used as compared with CBED. However, it is inevitable that the sample has a convergence angle of about several mrad due to focusing and irradiating the sample, and the diffraction pattern is limited-field electron diffraction pattern. It has a structure reflecting the sample structure in the disk. If a diffraction spot has a structure in this way, not only will there be arbitraryness in defining the distance between diffraction spots from the intensity profile, but there will also be a large error. Further, since it is a disc-shaped diffraction pattern, it is difficult to determine the maximum value at one point.

  To solve this problem, the distance between the diffraction patterns obtained by NBD is adjusted so that the shape of the condenser lens is reflected, and the boundary between the shadow of the condenser lens and the bright part (diffraction spot disk) It has been proposed to obtain the distance between diffraction patterns by measuring the distance of a portion where the luminance changes sharply.

JP 2009-250943 A

  With the above-described prior art, the intermediate lens can be adjusted so that the shadow of the condenser lens aperture clearly appears in the diffraction pattern. However, it is necessary to adjust the intermediate lens so that the shadow is reflected in the diffraction spot. Therefore, the operator at the site cannot easily adjust, and the diffraction spot is many times larger than usual, and the point where the brightness changes sharply at the boundary between the diffraction spot and the shadow of the condenser lens aperture is defined manually by the operator. Can not eliminate the arbitrary nature of. In addition, if a parallel beam can be obtained even after convergence due to NBD technological innovation, there is a problem that such a technique cannot be applied.

  The disclosed technology includes a step of generating two-level data by converting a gradation of an electron beam or an X-ray diffraction pattern representing a plurality of spots including a diffraction spot and a transmission spot, and using the two-level data, the spot Creating a definition circle corresponding to the area of the spot, and changing the size or coordinates of the definition circle so that the sum of squares of differences between the spot and each pixel of the definition circle is minimized. Obtaining an approximate circle of the spot by fitting to the center, and calculating the distance between spots by defining the coordinates of the spot with the center coordinates of the approximate circle, and obtaining a lattice plane distance. The semiconductor device evaluation method is configured to be executed by a computer.

  Further, as means for solving the above-described problems, a semiconductor device evaluation apparatus realized by a computer, a program for causing a computer to execute the semiconductor element evaluation method, and a recording medium recording the program are provided. You can also.

  In the disclosed technique, the coordinates of each spot in the nano-electron beam diffraction pattern can be appropriately defined, so that the lattice plane distance can be calculated with high accuracy.

It is a block diagram which shows the hardware constitutions of information processing apparatus. It is a figure which shows the example of the profile of the spot based on a NBD pattern. It is a figure which shows the function structural example of the information processing apparatus which concerns on a present Example. It is a flowchart for demonstrating the 1st example of the definition process of a spot coordinate. It is a figure for demonstrating the example of the definition process of a spot coordinate. It is a flowchart for demonstrating the 2nd example of the definition process of a spot coordinate. It is a flowchart for demonstrating the 3rd example of the definition process of a spot coordinate. It is a figure which shows the example of selection of a diffraction spot. It is a figure for demonstrating the difference in the precision by the presence or absence of application of a present Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. An electron beam diffraction pattern image (raw data) obtained by NBD is used as a method of defining the coordinates of the NBD diffraction pattern by eliminating the arbitraryness of the operator of the NBD measuring device that measures the amount of strain applied to the semiconductor element. There is a technique for obtaining the average coordinates of the two-graded bright spot portion by making two gradations (binary). The average coordinates of the bright spot are the coordinates of the electron beam transmission spot (hereinafter simply referred to as the transmission spot) and the coordinates of the electron beam diffraction spot (hereinafter simply referred to as the diffraction spot). Although the surface distance can be defined, the structure appears in the diffraction spot and the transmission spot, and when an asymmetric pattern is obtained, it is difficult to correctly define the spot coordinate in the average coordinate.

  The transmission and diffraction spots (both are collectively referred to simply as spots) originally have a Gaussian (normal) distribution, and the inventor focuses on the fact that they can be regarded as circles when two gradations are used. Is approximated by a circle, and the center of the approximated circle is used as the coordinates of the spot. According to the present embodiment, it is possible to define the spot coordinates with high accuracy while eliminating the arbitraryness of the operator of the NBD measuring apparatus.

  The information processing apparatus according to the present embodiment has a hardware configuration as shown in FIG. FIG. 1 is a block diagram illustrating a hardware configuration of the information processing apparatus. In FIG. 1, an information processing apparatus 100 is a terminal controlled by a computer, and includes a CPU (Central Processing Unit) 11, a memory unit 12, a display unit 13, an output unit 14, an input unit 15, and communication. The unit 16, the storage device 17, the driver 18, and an I / F (interface) 20 are included, and are connected to the system bus B.

  The CPU 11 controls the information processing apparatus 100 according to a program stored in the memory unit 12. The memory unit 12 uses a RAM (Random Access Memory), a ROM (Read-Only Memory), or the like, and is obtained by a program executed by the CPU 11, data necessary for processing by the CPU 11, and processing by the CPU 11. Stored data. A part of the memory unit 12 is allocated as a work area used for processing by the CPU 11.

  The display unit 13 displays various information required under the control of the CPU 11. The output unit 14 includes a printer or the like, and is used for outputting various types of information according to instructions from the user. The input unit 15 includes a mouse, a keyboard, and the like, and is used by a user to input various information necessary for the information processing apparatus 100 to perform processing. The communication unit 16 is a device that is connected to, for example, the Internet, a LAN (Local Area Network), and the like and controls communication with an external device. For example, a hard disk unit is used as the storage device 17 and stores data such as programs for executing various processes.

  A program that implements processing performed by the information processing apparatus 100 is provided to the information processing apparatus 100 by a storage medium 19 such as a CD-ROM (Compact Disc Read-Only Memory). That is, when the storage medium 19 storing the program is set in the driver 18, the driver 18 reads the program from the storage medium 19, and the read program is installed in the storage device 17 via the system bus B. . When the program is activated, the CPU 11 starts its processing according to the program installed in the storage device 17. The medium for storing the program is not limited to a CD-ROM, and any medium that can be read by a computer may be used. As a computer-readable storage medium, in addition to a CD-ROM, a portable recording medium such as a DVD disk or a USB memory, or a semiconductor memory such as a flash memory may be used.

  The I / F 20 is an interface for connecting to the NBD measurement device 21, and takes in diffraction data including a measurement result by the NBD measurement device 21. The acquired diffraction data is stored in the storage device 17. The acquisition of diffraction data is not limited to data transfer via the I / F 20, and may be stored in the storage device 17 via a storage medium.

  A method for defining the spot coordinates of the NBD pattern according to this embodiment will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a spot profile based on the NBD pattern. FIG. 2 shows an example of the NBD diffraction pattern 2 actually obtained and intensity profiles 3 and 4 extracted from the diffraction pattern 2. The diffraction pattern 2 is shown by diffraction data measured by the NBD measuring device 21.

  The two-gradation processing according to the present embodiment uses a transmission spot (Direct) in the diffraction pattern 2 and intensity files 3 and 4 indicating the intensity of the luminance of the diffraction spot, depending on the presence of an amorphized layer. Two-gradation is performed by setting the skirt of the distribution less than the intensity 3c deviating from the Gaussian distribution to 0 and setting the intensity 3c or more to 1. The intensity profiles 3 and 4 are included in diffraction data described later. The Gaussian distribution may be a two-dimensional Gaussian distribution.

  Then, the fitting process according to the present embodiment generates a definition circle having the same area as the two-level transmission spot, and sets the definition circle so that the sum of squares of differences between the transmission spot, the definition circle, and each pixel is minimized. Fitting by slightly scaling up or down by value to get an approximate circle. The center coordinates of the obtained approximate circle are defined as the coordinates of the transmission spot.

  Similarly, coordinates can be defined for each diffraction spot using intensity files 3, 4 and the like.

  A functional configuration for defining the spot coordinates of the NBD pattern will be described. FIG. 3 is a diagram illustrating an example of a functional configuration of the information processing apparatus according to the present embodiment. 3, the information processing apparatus 100 according to the embodiment includes a two-gradation processing unit 31, a definition circle creation processing unit 32, a fitting processing unit 33, and a distance calculation processing unit 34. When the CPU 11 executes a corresponding program, it functions as a two-gradation processing unit 31, a definition circle creation processing unit 32, a fitting processing unit 33, and a distance calculation processing unit 34. In addition, the information processing apparatus 100 includes data such as diffraction data 41, two-level gradation data 42, result data 43, and distance data 44 in the storage area 40 of the memory unit 12 or the storage device 17.

  The two-gradation processing unit 31 performs two-gradation on the diffraction data 41 that is image data representing the diffraction pattern 2. The two-gradation processing unit 31 converts the diffraction data 41 into two gradations with reference to the luminance intensity of each spot. In the Gaussian distribution representing the intensity of the luminance, the two-gradation data 42 in which the intensity less than the intensity deviating from the Gaussian distribution is set to 0 and the intensity above 1 is stored in the storage area 40.

  The definition circle creation processing unit 32 creates a circular definition circle serving as the area of the transmission spot using the two-gradation data 42 generated by the two-gradation processing unit 31. Similarly, a definition circle is created for the selected diffraction spot.

  The fitting processing unit 33 performs fitting to the transmission spot by slightly enlarging or reducing the definition circle created by the definition circle creation processing unit 32 by a predetermined value, and acquires an approximate circle. The fitting processing unit 33 stores the result data 43 including the size indicating the radius or diameter of the approximate circle and the coordinates indicating the center of the approximate circle in the storage area 40.

  The distance calculation processing unit 34 uses the result data 43 to calculate the distance between the transmission spot and each diffraction spot, and stores the distance data 44 in the storage area 40. Then, the NBD pattern generated based on the two-gradation data 42, the result data 43, and the distance data 44 is displayed on the display unit 13 of the information processing apparatus 100.

  FIG. 4 is a flowchart for explaining a first example of spot coordinate definition processing. In FIG. 4, the information processing apparatus 100 reads NBD diffraction data 41 (step S11), and the two-gradation processing unit 31 performs two-gradation of the diffraction data 41 (step S12). The two-gradation processing unit 31 stores in the storage area 40 the two-gradation data 42 in which less than a predetermined intensity of the Gaussian distribution representing the intensity of brightness of each spot is set to 0 and the specified intensity is 1 or more.

  Then, the information processing apparatus 100 sets the transmission spot in the two-gradation data 42 as the processing spot, and the definition circle creation processing unit 32 obtains the average coordinates and area from the pixels constituting the processing spot, A circle with the same area centered on the average coordinates is created and set as a definition circle (step S14).

  Next, the information processing apparatus 100 uses the fitting processing unit 33 to fit the definition circle to the spot being processed to obtain an approximate circle of the spot being processed (step S15). In step S15, processing from step S151 to S158 described below is performed.

  The fitting processing unit 33 moves the center coordinates of the definition circle so that the sum of squares of the difference between each spot between the spot being processed and the definition circle is minimized (step S151). Then, the fitting processing unit 33 slightly enlarges the definition circle (step S152), and moves the center coordinates of the definition circle so that the sum of squares of the difference between each pixel in the spot being processed and the definition circle is minimized (step S152). Step S153).

  The fitting processing unit 33 compares the square sum of the previous difference in step S151 with the square sum of the difference in step S152, and determines whether or not it is smaller than the square sum of the previous difference (step S154). If smaller than the sum of squares of the previous difference, the fitting processing unit 33 sets the sum of squares of the difference in step S152 to the sum of squares of the previous difference, returns to step S152, slightly increases the definition circle, The center coordinates of the definition circle are moved so that the sum of squares of the difference between each spot between the spot being processed and the definition circle is minimized (steps S152 and S153). The fitting processing unit 33 again compares the sum of squares of the previous difference and the sum of squares of the current difference (step S154), and if the sum of squares of the current difference is smaller than the sum of squares of the previous difference, The difference sum of squares is set to the previous difference sum of squares, the process returns to step S152, and the same processing is repeated until the current difference square sum is equal to or greater than the previous difference square sum.

  If it is determined in step S154 that the current sum of squares is equal to or greater than the sum of squares of the previous difference, the fitting processing unit 33 sets the sum of squares of the current difference to the sum of squares of the previous difference, and then the definition circle Is slightly reduced (step S155), and the center coordinates of the definition circle are moved so that the sum of squares of the difference between each spot between the spot being processed and the definition circle is minimized (step S156).

  Then, the fitting processing unit 33 compares the square sum of the previous difference with the square sum of the current difference, and determines whether or not the square sum of the current difference is smaller than the square sum of the previous difference ( Step S157). If the sum of squares of the previous differences is smaller than the previous sum of squares, the fitting processing unit 33 sets the current sum of squares of the previous differences to the sum of squares of the previous differences, and then returns to step S155. The same processing as described above is repeated until the sum of squares becomes equal to or greater.

  If it is determined in step S157 that the current sum of squares of the differences is greater than or equal to the previous sum of squares of the differences, the fitting processing unit 33 stores the size of the defined circle and the center coordinates in the result data 43 in the storage area 40. Recording is performed (step S158). The size of the definition circle is a radius or a diameter.

  Next, the information processing apparatus 100 determines whether there is an unprocessed diffraction spot selected by the user (step S16). If there is an unprocessed diffraction spot, the diffraction spot is set as a spot being processed (step S16-2), the process returns to step S14, and the same process as described above is repeated until the process is completed for all the diffraction spots.

  If it is determined in step S16 that the processing has been completed for all the diffraction spots, the information processing apparatus 100 calculates the distance from the transmission spot to each diffraction spot by the distance calculation processing unit 34 to obtain the lattice plane interval. The distance data 44 including the result is stored in the storage area 40 (step S17).

  The information processing apparatus 100 displays the result on the display unit 13 with reference to the two-gradation data 42, the result data 43, and the distance data 44 stored in the storage area 40 (step 18), and this processing Exit.

  In the processing in step S15 described above, the fitting processing unit 33 determines the optimum center coordinates of the definition circle while increasing or decreasing the radius of the definition circle at predetermined intervals.

  FIG. 5 is a diagram for explaining an example of spot coordinate definition processing. FIG. 5A shows an example of diffraction data 41 acquired from the NBD measurement device 21. FIG. 5B shows an example of the two-gradation data 42 in which the diffraction data 41 is two-gradated by the two-gradation processing unit 31. FIG. 5C shows an example of the definition circle 6 having the same area as the transmission spot 5 created by the definition circle creation processing unit 32 using the two-gradation data 42.

  The user may create the definition circle 6 from the two-gradation data 42 displayed on the display unit 13 by operating the mouse or the like. The size (radius or diameter) and area of the circle are acquired from the definition circle 6 created by the user.

  Next, the diffraction spot selected by the user and the diffraction spot located symmetrically through the transmission spot are analyzed simultaneously, and the distance X1 between the selected diffraction spot and transmission spot and the diffraction spot and transmission spot located symmetrically are analyzed. A case where fitting with a limiting condition that minimizes the difference from the distance X2 is performed will be described.

  FIG. 6 is a flowchart for explaining a second example of the spot coordinate definition process. In FIG. 6, steps that perform the same processing as the steps shown in FIG. 4 are given the same reference numerals, and descriptions thereof are omitted. In FIG. 6, with respect to the transmitted spot, the same processing described in FIG. 4 is performed from step S11 to step S16. In step S 15, the transmission spot size 0 and center coordinate 0 are recorded in the result data 43.

  If it is determined in step S16 that there is an unprocessed selected diffraction spot, the information processing apparatus 100 sets the diffraction spot selected by the user as the first processing spot, and transmits the first processing spot and the transmission spot. A diffraction spot positioned symmetrically through the spot is set as a spot in the second process (step S16-4).

  Then, the information processing apparatus 100 uses the definition circle creation processing unit 32 to create a definition circle from the pixels constituting the first processing spot and from the pixels constituting the second processing spot (step S19).

  The information processing apparatus 100 has a limiting condition that minimizes the difference between the distance X1 between the first processing spot and the transmission spot and the distance X2 between the second processing spot and the transmission spot. Fitting to the corresponding spot being processed is performed to obtain an approximate circle of the spot being processed (step S20), the process returns to step S16, and the same process is repeated until there is no unprocessed selected diffraction spot. In the process at step S20, the fitting processing unit 33 performs the fitting to the corresponding processing spot of each defined circle with a limiting condition while calculating the distance X1 and the distance X2 by the distance calculation processing unit 34.

  As a result of the processing in step S20, the size 1 and center coordinate 1 of the diffraction spot selected by the user and the size 2 and center coordinate 2 of the diffraction spot positioned symmetrically are added and recorded in the result data 43. Further, the distance X1 and the distance X2 that minimize the difference are recorded in the distance data 44.

  On the other hand, if it is determined in step S16 that there is no unprocessed selected diffraction spot, the information processing apparatus 100 stores the two-level gradation data 42, the result data 43, and the distance data 44 stored in the storage area 40. With reference to the result, the result is displayed on the display unit 13 (step 18), and this process is terminated.

  Next, fitting is performed with respect to the diffraction spot positioned symmetrically via the diffraction spot selected by the user and the transmission spot, and the distance D1 (= A case where distance X1 + distance X2) is calculated will be described.

  FIG. 7 is a flowchart for explaining a third example of the spot coordinate definition process. In FIG. 7, steps that perform the same processing as the steps shown in FIGS. 4 and 6 are given the same reference numerals, and descriptions thereof are omitted. In FIG. 7, the same processing described in FIG. 4 is performed for steps S11 to S16 regarding the transmitted spot. In step S 15, the transmission spot size 0 and center coordinate 0 are recorded in the result data 43.

  If it is determined in step S16 that there is an unprocessed selected diffraction spot, the information processing apparatus 100 sets the diffraction spot selected by the user as the first processing spot, and transmits the first processing spot and the transmission spot. A diffraction spot positioned symmetrically through the spot is set as a spot in the second process (step S16-4).

  Then, the information processing apparatus 100 uses the definition circle creation processing unit 32 to create a definition circle from the pixels constituting the first processing spot and from the pixels constituting the second processing spot (step S19). Unlike the second example of the spot coordinate definition process of FIG. 6, each definition circle is fitted without giving a limiting condition.

  In the information processing apparatus 100, the fitting processing unit 33 performs fitting to the corresponding spot in process of each definition circle to obtain an approximate circle of the spot being processed (step S20-4), and the process returns to step S16 and is unprocessed. The same process is repeated until the selected diffraction spot disappears.

  As a result of the processing in step S20-4, the size 1 and center coordinate 1 of the diffraction spot selected by the user and the size 2 and center coordinate 2 of the diffraction spot positioned symmetrically are added and recorded in the result data 43. However, unlike the second example of the spot coordinate definition process of FIG. 6, the distance data 44 is not recorded.

  On the other hand, if it is determined in step S16 that there is no unprocessed selected diffraction spot, the information processing apparatus 100 causes the distance calculation processing unit 34 to reduce the distance between diffraction spots that are symmetrical to each other through the transmission spot. Is calculated (step S17-4). A value that is ½ of the distance D1 from the diffraction spot selected by the user to the diffraction spot located symmetrically through the transmission spot is recorded in the distance data 44. When the user selects two diffraction spots, a value that is ½ of the distance D2 from the second diffraction spot to the diffraction spot located symmetrically through the transmission spot is recorded in the distance data 44.

  The information processing apparatus 100 displays the result on the display unit 13 with reference to the two-gradation data 42, the result data 43, and the distance data 44 stored in the storage area 40 (step 18), and this processing Exit.

  FIG. 8 is a diagram showing an example of selecting diffraction spots. In the diffraction pattern 8 shown in FIG. 8 displayed on the display unit 13, the information processing apparatus 100 is selected by the user in both of the spot coordinate definition processing in the second example of FIG. 6 and the third example of FIG. The diffraction spot 8b located symmetrically with respect to the {002} plane diffraction spot via the transmission spot 8a is specified. Further, when the user has selected a diffraction spot on the {022} plane, the information processing apparatus 100 specifies a diffraction spot 8c positioned symmetrically via the transmission spot 8a with respect to the diffraction spot on the {022} plane. .

  In the second example of the spot coordinate definition process of FIG. 6, the distance X1 between the diffraction spot of the {002} plane selected by the user and the transmission spot 8a and the distance X2 between the transmission spot 8a and the specified diffraction spot 8b are as follows. , And calculated based on the center coordinates of each spot. Similarly, for the selected diffraction spot of the {022} plane, a distance X1 ′ between the diffraction spot of the {022} plane and the transmission spot 8a, and a distance X2 ′ between the transmission spot 8a and the specified diffraction spot 8c Is calculated based on the center coordinates of each spot.

  In the third example of the spot coordinate definition process of FIG. 7, the distance D1 between the diffraction spot of the {002} plane selected by the user and the identified diffraction spot 8b is calculated based on the center coordinates of each spot. Similarly, the distance D2 between the diffraction spot on the {022} plane and the identified diffraction spot 8c is calculated based on the center coordinates of each spot. Half of each distance D1, D2 is displayed on the display unit 13 as the distance between the spots.

  Further, in the first example of the spot coordinate definition process of FIG. 4 in the case where the user selects each diffraction spot, the distances X1, X1 ′, X2, and X2 ′ between the diffraction spots and the transmission spot 8a are as follows. It is calculated individually based on the center coordinates.

  Since the plane spacing is equivalent, the distance X1 = X2 and the distance X1 ′ = X2 ′ are inherently established. Therefore, the distance corresponding to each surface is

It can be said that the accuracy is higher as indicated by.

  FIG. 9 is a diagram for explaining a difference in accuracy depending on whether or not the present embodiment is applied. FIG. 9A shows a display example of the result of measuring the end of the spot using the data obtained by making the diffraction data into two gradations. In FIG. 9B, a result display example in the case where processing such as fitting using a definition circle for obtaining the center coordinates of the spot according to the present embodiment is performed on the data obtained by converting the diffraction data into two gradations. Show.

In the result display example of FIG. 9A, processing such as fitting using a definition circle is not performed in order to obtain the center coordinates of the spot according to the present embodiment. Therefore, as described above, the distance between spots that should be the same distance to each surface is
Distance between diffraction spot 91 and transmission spot 90 = 3.78 cm
Distance between diffraction spot 92 and transmission spot 90 = 3.72 cm
Thus, the accuracy of the distance applying the above formula 2 is “0.016”. Also,
Distance between diffraction spot 93 and transmission spot 90 = 5.57 cm
Distance between diffraction spot 94 and transmission spot 90 = 5.20 cm
Thus, the accuracy of the distance to which the above formula 2 is applied is “0.096”.

  On the other hand, in the result display example of FIG. 9B, by applying this embodiment, an approximate circle fitted at each spot is shown, and the distance between the spots is determined using the center coordinates of each defined circle. Calculated.

Distance between diffraction spot 91 and transmission spot 90 = 3.76 cm
Distance between diffraction spot 91 and transmission spot 90 = 3.78 cm
Thus, the accuracy of the distance to which the above equation 2 is applied is “0.005”. Also,
Distance between diffraction spot 93 and transmission spot 90 = 5.39 cm
Distance between diffraction spot 94 and transmission spot 90 = 5.39 cm
Thus, the accuracy of the distance obtained by applying the above formula 2 is “0.000”. Therefore, the distance between each spot is shown with the same distance with respect to each surface.

  As described above, when the present embodiment is applied, the coordinates of each spot in the nano-electron beam diffraction pattern can be appropriately defined, so that the distance can be calculated with high accuracy.

  Therefore, although distortion due to doping or heterogeneous (hetero) stress occurs in the semiconductor element substrate, it is possible to appropriately evaluate how much distortion has occurred. Although distortion also occurs in the patterns of the diffraction spot and the transmission spot that reflect the lattice spacing, application of this embodiment makes it possible to measure the distance between these spots more accurately.

  In addition, due to the NBD technological innovation, it can be applied to a parallel X-ray beam even if converged, and can also be applied to limited-field electron diffraction.

  The present invention is not limited to the specifically disclosed embodiments, and various modifications and changes can be made without departing from the scope of the claims. Further, the present invention is not limited to electron beam diffraction spots, and can be applied to X-ray diffraction patterns.

The following additional notes are further disclosed with respect to the embodiment including the above examples.
(Appendix 1)
Two-level gradation of electron beam or X-ray diffraction patterns representing a plurality of spots including diffraction spots and transmission spots, and generating two-level gradation data;
Creating a definition circle corresponding to the spot region using the two-gradation data;
An approximate circle of the spot is obtained by fitting to the spot by changing at least one of the size or coordinates of the definition circle so that the sum of squares of the differences between the spot and each pixel of the definition circle is minimized. And steps to
A method of evaluating a semiconductor device, wherein the computer executes a step of calculating a distance between spots and obtaining a lattice plane distance by defining the coordinates of the spots with the center coordinates of the approximate circle.
(Appendix 2)
2. The evaluation method of a semiconductor device according to appendix 1, wherein the two-gradation data indicates 0 less than an intensity deviating from a Gaussian distribution representing the intensity of brightness of each spot, and indicates 1 above the intensity.
(Appendix 3)
3. The semiconductor element evaluation method according to appendix 2, wherein the Gaussian distribution is a two-dimensional Gaussian distribution.
(Appendix 4)
3. The semiconductor element evaluation method according to appendix 1 or 2, wherein a definition circle corresponding to the spot region is created using an average coordinate of pixels of the spot.
(Appendix 5)
Identifying a diffraction spot selected by the user and a diffraction spot located symmetrically via the transmission spot;
When fitting to the spot, according to a limiting condition that minimizes the difference between the first distance between the selected diffraction spot and the transmission spot and the second distance between the symmetrical diffraction spot and the transmission spot. The semiconductor element evaluation method according to any one of appendices 1 to 3, wherein at least one of a size or a coordinate of a definition circle corresponding to each spot is changed to fit to each spot.
(Appendix 6)
Identifying a diffraction spot selected by the user and a diffraction spot located symmetrically via the transmission spot;
4. The calculation of the distance between the spots, wherein the distance between the selected diffraction spot and the symmetrical diffraction spot is halved to obtain the grating plane distance. The evaluation method of the semiconductor element of description.
(Appendix 7)
6. The semiconductor element evaluation method according to claim 1, wherein the defined circle is set by a user.
(Appendix 8)
Generation means for generating two-gradation data by two-grading an electron beam or an X-ray diffraction pattern representing a plurality of spots including a diffraction spot and a transmission spot;
Creating means for creating a definition circle corresponding to the spot area using the two-gradation data;
An approximate circle of the spot is obtained by fitting to the spot by changing at least one of the size or coordinates of the definition circle so that the sum of squares of the differences between the spot and each pixel of the definition circle is minimized. Approximating circle acquisition means to
An apparatus for evaluating a semiconductor device, comprising: distance acquisition means for calculating a distance between spots and acquiring a lattice plane distance by defining the coordinates of the spots with the center coordinates of the approximate circle.
(Appendix 9)
Two-level gradation of electron beam or X-ray diffraction patterns representing a plurality of spots including diffraction spots and transmission spots, and generating two-level gradation data;
Creating a definition circle corresponding to the spot region using the two-gradation data;
An approximate circle of the spot is obtained by fitting to the spot by changing at least one of the size or coordinates of the definition circle so that the sum of squares of the differences between the spot and each pixel of the definition circle is minimized. And steps to
A computer-executable evaluation of a semiconductor device, characterized in that a computer executes a step of calculating a distance between spots and obtaining a lattice plane distance by defining the coordinates of the spot with a center coordinate of the approximate circle program.
(Appendix 10)
Two-level gradation of electron beam or X-ray diffraction patterns representing a plurality of spots including diffraction spots and transmission spots, and generating two-level gradation data;
Creating a definition circle corresponding to the spot region using the two-gradation data;
An approximate circle of the spot is obtained by fitting to the spot by changing at least one of the size or coordinates of the definition circle so that the sum of squares of the differences between the spot and each pixel of the definition circle is minimized. And steps to
An evaluation program for a semiconductor device is stored, wherein a computer executes a step of calculating a distance between spots and obtaining a lattice plane distance by defining the coordinates of the spots with the center coordinates of the approximate circle A computer-readable storage medium.

2 Diffraction pattern 3, 4 Intensity file 5 Transmission spot 6 Definition circle 11 CPU
12 memory unit 13 display unit 14 output unit 15 input unit 16 communication unit 17 storage device 18 driver 19 storage medium 20 I / F
21 NBD measurement apparatus 31 Two-gradation processing unit 32 Definition circle creation processing unit 33 Fitting processing unit 34 Distance calculation processing unit 40 Storage area 41 Diffraction data 42 Two-gradation data 43 Result data 44 Distance data

Claims (6)

Two-level gradation of electron beam or X-ray diffraction patterns representing a plurality of spots including diffraction spots and transmission spots, and generating two-level gradation data;
Creating a definition circle corresponding to the spot region using the two-gradation data;
An approximate circle of the spot is obtained by fitting to the spot by changing at least one of the size or coordinates of the definition circle so that the sum of squares of the differences between the spot and each pixel of the definition circle is minimized. And steps to
A method of evaluating a semiconductor device, wherein the computer executes a step of calculating a distance between spots and obtaining a lattice plane distance by defining the coordinates of the spots with the center coordinates of the approximate circle.   2. The method for evaluating a semiconductor device according to claim 1, wherein the two-gradation data indicates less than an intensity deviating from a Gaussian distribution representing the intensity of brightness of each spot by 0, and indicates 1 or more by the intensity.   3. The method of evaluating a semiconductor device according to claim 2, wherein the Gaussian distribution is a two-dimensional Gaussian distribution.   4. The semiconductor element evaluation method according to claim 1, wherein a definition circle corresponding to the spot region is created using average coordinates of pixels of the spot. Identifying a diffraction spot selected by the user and a diffraction spot located symmetrically via the transmission spot;
When fitting to the spot, according to a limiting condition that minimizes the difference between the first distance between the selected diffraction spot and the transmission spot and the second distance between the symmetrical diffraction spot and the transmission spot. 5. The semiconductor element evaluation method according to claim 1, wherein at least one of a size or a coordinate of a definition circle corresponding to each spot is changed to fit to each spot. Generation means for generating two-gradation data by two-grading an electron beam or an X-ray diffraction pattern representing a plurality of spots including a diffraction spot and a transmission spot;
Creating means for creating a definition circle corresponding to the spot area using the two-gradation data;
An approximate circle of the spot is obtained by fitting to the spot by changing at least one of the size or coordinates of the definition circle so that the sum of squares of the differences between the spot and each pixel of the definition circle is minimized. Approximating circle acquisition means to
An apparatus for evaluating a semiconductor device, comprising: distance acquisition means for calculating a distance between spots and acquiring a lattice plane distance by defining the coordinates of the spots with the center coordinates of the approximate circle.