Pattern length measurement and defect inspection method, image data processing system, and computer-readable recording medium.

Abstract

To rapidly correct periodic misalignment by using periodic information and coordinate correction of design data, the present disclosure proposes a method for performing length measurement or defect inspection of a pattern existing in a pattern formation region formed on a sample by performing first alignment processing between design information relating to the pattern formation region and a first image obtained by capturing at least a part of the pattern formation region to identify first position information relating to the first image, the method comprising acquiring periodic information that relates to the pattern formation region and is based on a result of autocorrelation processing using the design information, and, on the basis of the periodic information, outputting or correcting the first position information relating to the first image, or determining whether or not the first alignment processing is good (see FIG. 2).

Description

Technical Field

[0004] , , , , , , , , , , , , , , , , , , ,

[0005] ,

[0001] The present disclosure relates to a pattern length measurement and defect inspection method, an image data processing system, and a computer-readable recording medium.

Background Art

[0002] In the semiconductor manufacturing process, generally, measurement, inspection, and analysis of circuit patterns on a semiconductor integrated circuit are performed. As one of the methods for measuring, inspecting, and analyzing circuit patterns, there is a method of using CAD (Computer Aided Design) data, which is design data of the circuit pattern, as a reference pattern. In this method, the circuit pattern is evaluated and the cell to be analyzed is specified by comparing the SEM image obtained by imaging the actually formed pattern with the CAD data.

[0003] Regarding the evaluation of the circuit pattern and the specification of the cell to be analyzed, alignment between the SEM image and the design data is performed using the design data. Regarding this alignment process, there are many known examples as shown in Patent Documents 1 to 4 below, for example.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] In semiconductor patterns with characteristic repeating patterns (hereinafter referred to as "periodic patterns"), a periodic misalignment can occur between the circuit pattern actually formed on the semiconductor integrated circuit and the pattern in the design data during pattern alignment, resulting in a decrease in alignment accuracy. In other words, although pattern correlation is maintained between the SEM image and the design data, in the case of periodic patterns, a positional misalignment of one or more periods may occur. If alignment is deemed complete while this periodic misalignment exists, it will affect the accuracy of subsequent length measurement and defect inspection results.

[0006] In light of these circumstances, this disclosure proposes a technology for rapidly correcting periodic deviations using periodicity information and coordinate correction in design data. [Means for solving the problem]

[0007] To solve the above problems, this disclosure proposes a method for determining first position information of a first image by performing a first alignment process between design information of a pattern-forming region formed on a sample and a first image obtained by imaging at least a part of the pattern-forming region, and for measuring the length of a pattern present in the pattern-forming region or inspecting for defects, the method comprising: obtaining periodicity information in the pattern-forming region based on the results of autocorrelation processing using the design information; and outputting or correcting the first position information of the first image based on the periodicity information, or determining the quality of the first alignment process.

[0008] Further features relating to this disclosure will become apparent from the description herein and the accompanying drawings. Furthermore, aspects of this disclosure are achieved and realized by elements and various combinations of elements and the modes of the claims described herein in detail thereafter.

[0009] The descriptions herein are typical examples only and do not limit in any way the claims or applications of this disclosure. [Effects of the Invention]

[0010] The technology disclosed herein makes it possible to correct periodic misalignment at high speed or to determine the quality of the alignment process. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows a schematic configuration example of the semiconductor measurement and inspection system 100 according to this embodiment. [Figure 2] Figure 1 is a flowchart illustrating the overall overview of the period shift correction process using the semiconductor measurement and inspection system 100. [Figure 3] Figure 2 is a flowchart illustrating the details of the periodicity information acquisition process in step 204. [Figure 4] This figure shows design data template 401, first template 402, and SEM image 403. [Figure 5] This figure shows the periodicity search in the X direction and the periodicity search in the Y direction. [Figure 6] This figure shows the periodicity search in the diagonal direction. [Figure 7] This is a flowchart illustrating the details of the periodic shift correction process in step 208 of Figure 2 according to the first embodiment. [Figure 8] This is a flowchart illustrating the details of the periodic shift correction process in step 208 of Figure 2, according to the second embodiment. [Figure 9] This figure shows an example of the imaging location in SEM images. [Figure 10] This diagram illustrates periodicity information and periodic position (alignment candidate 1). [Figure 11] This diagram illustrates periodicity information and periodic position (alignment candidate 2). [Figure 12] This diagram illustrates a specific example of calculating coordinate errors. [Figure 13] This figure illustrates the periodic position after the alignment results of the second SEM images have been added together. [Figure 14]This is a diagram for explaining the periodic position and coordinate error after adding the alignment results of the second SEM image.

Embodiments for Carrying Out the Invention

[0012] Embodiments of the present disclosure relate to a pattern measurement inspection apparatus (including a FIB apparatus and a probe apparatus), obtain periodic information using design data representing a shape serving as a reference for inspection or measurement of a semiconductor pattern, analysis such as internal wiring or electrical property measurement of a semiconductor device, and correct a periodic shift using a SEM image and the periodic information acquired by the pattern measurement inspection apparatus.

[0013] Hereinafter, a method for obtaining periodic information from a pattern on design data and a specific example of a semiconductor measurement / inspection system that corrects a periodic shift by coordinate correction using the periodic information will be described with reference to the accompanying drawings. In the embodiments of the present disclosure, it is assumed that the wafer position imaged by the semiconductor measurement / inspection apparatus is only the defect position, and the sampled positions within the wafer are imaged.

[0014] In this embodiment, although the description is made in sufficient detail for those skilled in the art to implement the present disclosure, other implementation forms are also possible, and it is necessary to understand that changes in configuration and structure and replacement of various elements can be made without departing from the scope and spirit of the technical idea of the present disclosure. Therefore, the following description should not be construed as being limited thereto.

[0015] (1) First Embodiment <System Configuration Example> Figure 1 shows a schematic configuration example of the semiconductor measurement and inspection system 100 according to this embodiment. The semiconductor measurement and inspection system 100 includes a scanning electron microscope (SEM) 101 for measuring and inspecting circuit patterns formed on a wafer, a computer system 1_111, a computer system 2_116, a design information database 120, and an input / output device 121 such as a user PC. The scanning electron microscope 101 and computer 1_111 are connected via network 1_110. Computer 1_111, computer 2_116, the design information database 120, and the input / output device 121 are connected via network 2_115.

[0016] SEM101 integrates the basic components of a SEM: an electron beam column 102, a vacuum sample chamber 105, and a sample stage (XY stage) 106. During pattern inspection, an electron beam 104 is irradiated from an electron source 103 onto a sample 107, such as a wafer on which a device has been manufactured. The irradiated electron beam is focused using multiple lenses and deflected and scanned using a scanning deflector. This causes the electron beam to scan the sample surface in one or two dimensions. Secondary electrons or backscattered electrons 108 emitted from the sample by the electron beam scanning are detected by a detector and converted into a digital signal by an A / D converter 109. The digital signal is input to a computer system 1_111 via a network 1_110 and stored in a memory unit 114.

[0017] The computer system 1_111 controls various modules of the apparatus, including the electron beam column, stage, and vacuum sample chamber, via the control unit 113. During pattern inspection, the computer system 1_111 also reads the digital signals stored in the memory unit 114 via the calculation processing unit 112, performs various calculations including signal processing (SEM image generation) and image processing for acquiring measurement target information, and stores and manages the generated SEM images and various calculation results in the memory unit 114.

[0018] The arithmetic processing unit 112 of the computer system 1_111 has the function of creating a program (recipe) to control the operation of the SEM 101 based on the design data of the semiconductor device, and also functions as a recipe setting unit. Specifically, the arithmetic processing unit 112 sets position information (e.g., design data, pattern contour data, desired measurement points on the simulated design data, autofocus points, autostigma points, addressing points, etc.) for the SEM 101 to perform the necessary processing in response to the operator's input instructions. Then, the arithmetic processing unit 112 creates a program to automatically control the sample stage 106 and deflector of the SEM 101 based on these settings.

[0019] The computer system 2_116 uses the arithmetic processing unit 117 to perform measurement and defect inspection processing (generating measurement and inspection result information) and statistical processing, and stores the processing results in the storage unit 119. In addition, the computer system 2_116 uses the image processing unit 118 to perform image processing and output processing, as well as saving and managing the image processing results in the storage unit 119.

[0020] The design information database 120 stores design information (design data) for semiconductor circuit patterns. The design data consists of, for example, layer information, which is information about each layer of the stacked circuit pattern, and shape information of the circuit pattern of each layer.

[0021] The input / output device 121, such as a user PC, is connected to network 2_115 and used by the operator to perform various operations on the SEM 101, including executing and creating recipes on computer system 1_111. Furthermore, by connecting the input / output device 121 to computer system 2_116, measurement processing and statistical processing can be performed remotely. In addition, the operator can access the design information database 120 from the input / output device 121 to query, acquire, save, and create design data.

[0022] Although the semiconductor measurement and inspection system 100 shown in Figure 1 includes multiple computers, such as computer 1_111 and computer 2_116, each handling different processes, it may also include only one computer and have it perform all the processing. Alternatively, computer system 2_116, design information database 120, and input / output device 121 may be configured as a single system, and this system may be connected to computer system 1_111 via a network.

[0023] <Periodic shift correction process: Overall process overview> Figure 2 is a flowchart illustrating the overall overview of the periodic shift correction process using the semiconductor measurement and inspection system 100 shown in Figure 1. Details of the periodicity information acquisition process (step 204) and the periodic shift correction process using the periodicity information (step 207), which are included in the overall overview of the periodic shift correction process, will be described later.

[0024] (i) Step 201 The arithmetic processing unit 112 of the computer system 1_111 creates an SEM image acquisition recipe using a recipe creation function based on the design data of the semiconductor device. The SEM 101 performs the imaging operation according to the created recipe. At this time, the control unit 113 of the computer system 1_111 performs stage movement according to the recipe. The arithmetic processing unit 112 also performs pattern inspection of the sample on the SEM 101 using signal processing, etc., acquires an acquired image (hereinafter referred to as the SEM image), and acquires supplementary information including acquisition condition information during imaging (for example, information on current and voltage values ​​during imaging, coordinate positions of wafers and chips, etc.), and stores it in the storage unit 114 of the computer system 1_111.

[0025] (ii) Step 202 Computer system 2_116 acquires the captured image (SEM image) and associated information stored in the memory unit 114 of computer system 1_111 via network 2_115, and reads the associated information. During the process of reading the associated information, imaging position information such as wafer coordinates and chip coordinates, which will be used in step 702 (see Figure 7) described later, is acquired.

[0026] (iii) Step 203 Computer system 2_116 reads a pre-created design data template from the design information database 120. The design data template is design data corresponding to the acquired SEM image (image set). This design data template can be configured so that the FOV (Field of View) is twice the area of ​​the SEM image's FOV (twice is just one example).

[0027] (iv) Step 204 Computer system 2_116 performs autocorrelation processing using the loaded design data to obtain periodicity information. For example, computer system 2_116 obtains periodicity information of the target FOV using a first template that corresponds to the central part of the design data template within the target FOV. The area to be used as the first template may be set by the operator using a GUI or the like from an area within the design data (design data template). Alternatively, for example, the first template can be an area within the target FOV that corresponds to the central part of the design data template. Details of obtaining periodicity information by autocorrelation processing will be described later (see Figure 3).

[0028] (v) Step 205 Computer system 2_116 performs pattern matching using template matching and normalized cross-correlation methods with the loaded SEM images and design data to align the SEM images and design data.

[0029] (vi) Step 206 Computer system 2_116 performs pattern measurement and defect inspection based on the design data. Note that this pattern measurement and defect inspection may also be performed by computer system 1_111.

[0030] (vii) Step 207 The computer system 2_116 performs periodic shift correction processing using the periodicity information acquired in step 204, the alignment results of the SEM image and design data acquired in step 205, and the imaging position information. Details of the periodic shift correction processing will be described later (see Figure 7).

[0031] (viii) Step 208 The computer system 2_116 determines, based on predetermined operations, whether or not to provide the design data coordinates (periodic shift correction results) identified by periodic shift correction to the downstream system. Here, "operations" refers to cases where, for example, an FIB device or probe device is connected downstream of the semiconductor measurement and inspection system 100, and it is specified that the downstream device use the design data identified by periodic shift correction. In this case, the downstream system (FIB device or probe device) uses the periodic shift correction results to determine the deposit film formation area during cross-sectional analysis and to determine the position to apply the probe.

[0032] If the period shift correction result is to be provided to the downstream system (if the answer is Yes in step 208), the process proceeds to step 209. On the other hand, if the period shift correction result is not to be provided to the downstream system (if the answer is No in step 208), the process proceeds to step 210.

[0033] (ix) Step 209 Computer system 2_116 provides the downstream system with the design data coordinates (periodic shift correction results) identified by periodic shift correction.

[0034] (x) Step 210 The computer system 2_116 transmits the periodic shift correction results to the input / output device 121. The input / output device 121 visualizes the periodic shift correction results (for example, an image in which the periodic shift-corrected SEM image and the design data are superimposed, or SEM images before and after periodic shift correction) (for example, by displaying them on a screen).

[0035] <Details of the periodic information acquisition process> The periodicity information acquisition process will be explained with reference to Figures 3 to 6. Figure 3 is a flowchart illustrating the details of the periodicity information acquisition process in step 204 of Figure 2. Figure 4 shows the design data template 401, the first template 402, and the SEM image 403. Figure 5 shows the periodicity search in the X direction and the periodicity search in the Y direction. Figure 6 shows the periodicity search in the diagonal direction.

[0036] (i) Step 301 Computer system 2_116 performs autocorrelation processing using design data (design data template) 401 stored in the design information database 120.

[0037] (ii) Step 302 The computer system 2_116 uses the autocorrelation processing results (map, distribution, etc.) from step 301 and the first template 402 within the predetermined target FOV to search for the presence of the first template 402 in the first direction (e.g., the X direction) 501 (see Figure 5) and acquire periodicity information. If two or more periodicities cannot be confirmed, the search is terminated at that point. The first template may be determined to have the same FOV as the SEM image 403 of the object being measured and inspected. The periodicity information includes information indicating the presence or absence of periodicity in the first template in the search direction, information on the number of periodicity matching points (the presence or absence of periodicity can be determined depending on the presence or absence of matching points), and information on the periodic interval.

[0038] (iii) Step 303 The computer system 2_116 uses the autocorrelation processing results from step 301 and the first template to search for the presence of the first template in the second direction (e.g., the Y direction) 502 (see Figure 5) and obtain periodicity information. At this time, as in step 302, if two or more periodicities cannot be confirmed, the search is terminated at that point.

[0039] (iv) Step 304 The computer system 2_116 uses the autocorrelation processing results from step 301 and the first template to search for the presence of the first template in the third direction (diagonal direction) 601 (see Figure 6) and obtain periodicity information. At this time, as with steps 302 and 303, if two or more periodicities cannot be confirmed, the search is terminated at that point.

[0040] (v) Step 305 The computer system 2_116 outputs the periodicity information acquired in steps 302 to 304 as periodicity information (file data) for each SEM image and design data, or attaches it to the relevant SEM image.

[0041] <Details of period shift correction process> Figure 7 is a flowchart illustrating the details of the periodic shift correction process in step 208 of Figure 2.

[0042] (i) Step 701 The computer system 2_116 (for example, the arithmetic processing unit 117) uses the periodicity information acquired in step 204 (based on the information regarding the presence or absence of periodicity) to classify each SEM image into a group of SEM images having a periodic pattern or a group of SEM images having a non-periodic pattern.

[0043] (ii) Step 702 Computer system 2_116 searches (identifies) the SEM image with a non-periodic pattern (hereinafter referred to as the second SEM image) that is closest to each image in the SEM image group with a periodic pattern (hereinafter referred to as the first SEM image) from among the SEM image group with a non-periodic pattern. Imaging position information 901 such as the wafer coordinates and chip coordinates of the SEM images is used for the search. Computer system 2_116 then calculates the distance (two-point distance) between the first SEM image and each SEM image with a non-periodic pattern. For example, in Figure 9, the two-point distance between the first SEM image 902 and the second SEM image 903, and the two-point distance between the first SEM image 902 and the second SEM image 904 are calculated. Furthermore, computer system 2_116 identifies the combination that has the shortest two-point distance and uses the SEM image with a non-periodic pattern as the second SEM image to be used for periodic shift correction. Note that the method for calculating the two-point distance at this time may be any.

[0044] (iii) Step 703 Computer system 2_116 determines whether it is necessary to correct for detailed coordinate errors between the first SEM image and the second SEM image. Here, detailed coordinate errors refer to the design data (design data This refers to coordinate errors other than those caused by alignment with template 401). Detailed coordinate error correction is performed, for example, in the following three cases: (iii-1) When the operator instructs the execution of periodic shift correction via a GUI (such as a GUI displayed on the screen of the input / output device 121) according to the required coordinate accuracy; (iii-2) When there is a stage movement between the acquisition of the first SEM image and the acquisition of the second SEM image; (iii-3) When the distance between two points in the first SEM image and the second SEM image exceeds a predetermined threshold (an arbitrary threshold specified by the operator via a GUI, etc.). Periodic shift correction may be performed when at least one of these three conditions is met, or when two or more conditions are met.

[0045] If the operator wants to correct the positional misalignment with high precision, if there is a stage movement, or if the distance between two points exceeds a predetermined threshold (if the answer is Yes in step 703), the process proceeds to step 705. If high-precision positional misalignment correction is not required, if there is no stage movement, or if the distance between two points does not exceed a predetermined threshold (if the answer is No in step 703), the process proceeds to step 704. Here, coordinate error refers to the amount of misalignment when the first SEM image and the second SEM image are aligned to an ideal position without periodic shift.

[0046] (iv) Step 704 Computer system 2_116 uses the alignment result (alignment shift amount) between the second SEM image and the design data template as the periodic shift-corrected coordinate of the first SEM image. In other words, the amount of shift between the second SEM image and the design data is used directly as the correction amount for the first SEM image.

[0047] (v) Step 705 Computer system 2_116 calculates the coordinate error. To do this, computer system 2_116 first calculates all periodic positions from the periodicity information of the first SEM image. For example, consider a design data template 1001 with a periodic template 1004 (corresponding to the first template mentioned above), where the periodic width 1002, periodic height 1003, and one periodic point in each direction (X, Y, and diagonal directions). In this case, nine periodic positions (matching positions) can be calculated from this information (nine is just an example; 1005 to 1009: see Figure 10, and 1101 to 1104: see Figure 11). Next, the computer system 2_116 adds the alignment result (the above alignment shift amount) 1201 with the design data of the second SEM image to the centroid position of the periodic position (1202 to 1206: see Figure 12, 1301 to 1304: see Figure 13), and identifies the periodic position 1306 that is closest to the alignment result 1305 of the first SEM image. Then, the computer system 2_116 takes the difference 1307 between the identified periodic position 1306 and the alignment result 1305 of the first SEM image as the coordinate error.

[0048] To make it easier to understand, a specific example will be explained with reference to Figure 14. Figure 14 is a diagram illustrating a specific example of coordinate error calculation. As an example, the amount of deviation (amount of deviation of the center position) between the first SEM image (periodic pattern) 1401 and the design data (design data template) will be defined as the detected position (14,15), and the amount of deviation between the second SEM image (non-periodic pattern) 1402 and the design data will be defined as the correct position (2,3). Furthermore, as described above, it is assumed that there is one periodic point (periodic position) in the X direction, Y direction, and diagonal direction, and as shown in Figures 10 and 11, a periodic position list 1403 is obtained as a result of searching for periodic positions, such as (-10,10), (0,10), (10,10), (-10,0), (0,0), (10,0), (-10,-10), (0,-10), (10,-10). At this point, adding the correct position (2,3) obtained from the non-periodic pattern to each periodic position yields (-8,13), (2,13), (12,13), (-8,3), (2,3), (12,3), (-8,-7), (2,-7), and (12,-7). From this added periodic position 1404, the nearest periodic position (12,13) ​​to the detected position (14,15) is identified, so the offset 1405 between (14,15) and (12,13) ​​is found to be (2,2). This offset 1405 is the coordinate error.

[0049] (vi) Step 706 Computer system 2_116 calculates the corrected coordinates by adding the coordinate error obtained in step 705 to the alignment result of the second SEM image. In the specific example in Figure 12, the correct position 1406=(4,5) of the first SEM image is obtained by adding the offset 1405 and the correct position (2,3). This correct position 1406 becomes the corrected coordinates. In this specific example, the periodic shift amount 1407 is the amount of shift from the correct position 1406 to the detected position, and is (4,5)-(14,15)=(-10,-10).

[0050] (vii) Step 707 Computer system 2_116 outputs the correction result or period shift correction result of the first SEM image calculated in step 704 or step 706.

[0051] (2) Second embodiment The first embodiment described above describes periodic shift correction processing using images of non-contiguous regions on a wafer or chip (images of randomly selected regions). The second embodiment describes periodic shift correction using images of continuous regions on a wafer or chip.

[0052] <System Configuration> The system used in the second embodiment can employ the same configuration as the semiconductor measurement and inspection system 100 shown in Figure 1, as in the first embodiment. Therefore, a detailed explanation is omitted here.

[0053] <Periodic shift correction process: Overall process overview> The overall outline of the periodic shift correction process and the periodicity information acquisition process according to the second embodiment are the same as those of the first embodiment (see Figure 2 for the overall outline of the periodic shift correction process and Figure 3 for the periodicity information acquisition process). Therefore, a detailed explanation is omitted here.

[0054] <Details of period shift correction process> Figure 8 is a flowchart illustrating the details of the periodic shift correction process according to the second embodiment. The difference from the first embodiment (Figure 7) lies in the process in step 802. This difference stems from the fact that the second embodiment performs periodic shift correction using captured images of a continuous region on the wafer or chip.

[0055] (i) Step 801 The computer system 2_116 (for example, the arithmetic processing unit 117) uses the periodicity information acquired in step 204 (based on the information regarding the presence or absence of periodicity) to classify each SEM image into a group of SEM images having a periodic pattern or a group of SEM images having a non-periodic pattern.

[0056] (ii) Step 802 Computer system 2_116 searches (identifies) the SEM image with a non-periodic pattern (hereinafter referred to as the second SEM image) that is closest to each image in the SEM image group with a periodic pattern (hereinafter referred to as the first SEM image) from among the SEM image group with a non-periodic pattern. Specifically, continuous regions are imaged according to the image acquisition method (imaging conditions) on the device side. Therefore, computer system 2_116 designates the image acquired before the first SEM image and classified in step 801 as the SEM image group with a non-periodic pattern as the second SEM image. On the other hand, if there is an image in the nearest vicinity that has already undergone period shift correction, computer system 2_116 sets this image as the second SEM image (for period shift correction). In the second embodiment, since images are acquired in a continuous region, there is no need to search for non-periodic patterns (unique patterns) in the vicinity of the periodic pattern. Also, the second SEM image may be an image within the same chip.

[0057] (iii) Step 803 Computer system 2_116 determines whether it is necessary to correct for detailed coordinate errors between the first SEM image and the second SEM image. Here, detailed coordinate errors refer to the design data (design data This refers to coordinate errors other than those caused by alignment with template 401). Detailed coordinate error correction is performed, for example, in the following three cases: (iii-1) When the operator instructs the execution of periodic shift correction via a GUI (such as a GUI displayed on the screen of the input / output device 121) according to the required coordinate accuracy; (iii-2) When there is a stage movement between the acquisition of the first SEM image and the acquisition of the second SEM image; (iii-3) When the distance between two points in the first SEM image and the second SEM image exceeds a predetermined threshold (an arbitrary threshold specified by the operator via a GUI, etc.). Periodic shift correction may be performed when at least one of these three conditions is met, or when two or more conditions are met.

[0058] If the operator wants to correct the positional misalignment with high precision, if there is a stage movement, or if the distance between two points exceeds a predetermined threshold (if the answer is Yes in step 803), the process proceeds to step 805. If high-precision positional misalignment correction is not required, if there is no stage movement, or if the distance between two points does not exceed a predetermined threshold (if the answer is No in step 803), the process proceeds to step 804. Here, coordinate error refers to the amount of misalignment when the first SEM image and the second SEM image are aligned to an ideal position without periodic shift.

[0059] (iv) Step 804 Computer system 2_116 uses the alignment result (alignment shift amount) between the second SEM image and the design data template as the periodic shift-corrected coordinate of the first SEM image. In other words, the amount of shift between the second SEM image and the design data is used directly as the correction amount for the first SEM image.

[0060] (v) Step 805 Computer system 2_116 calculates the coordinate error. To do this, computer system 2_116 first calculates all periodic positions from the periodicity information of the first SEM image. For example, consider a design data template 1001 with a periodic template 1004 (corresponding to the first template mentioned above), where the periodic width is 1002, the periodic height is 1003, and there is one periodic point in each direction (X, Y, and diagonal directions). In this case, nine periodic positions (matching positions) can be calculated from this information (1005 to 1009: see Figure 10, and 1101 to 1104: see Figure 11). Next, the computer system 2_116 adds the alignment result (the above alignment shift amount) 1201 with the design data of the second SEM image to the centroid position of the periodic position (1202 to 1206: see Figure 12, 1301 to 1304: see Figure 13), and identifies the periodic position 1306 that is closest to the alignment result 1305 of the first SEM image. Then, the computer system 2_116 takes the difference 1307 between the identified periodic position 1306 and the alignment result 1305 of the first SEM image as the coordinate error.

[0061] To make it easier to understand, a specific example will be explained with reference to Figure 14. Figure 14 is a diagram illustrating a specific example of coordinate error calculation. As an example, the amount of deviation (amount of deviation of the center position) between the first SEM image (periodic pattern) 1401 and the design data (design data template) will be defined as the detected position (14,15), and the amount of deviation between the second SEM image (non-periodic pattern) 1402 and the design data will be defined as the correct position (2,3). Furthermore, as described above, it is assumed that there is one periodic point (periodic position) in the X direction, Y direction, and diagonal direction, and as shown in Figures 10 and 11, a periodic position list 1403 is obtained as a result of searching for periodic positions, such as (-10,10), (0,10), (10,10), (-10,0), (0,0), (10,0), (-10,-10), (0,-10), (10,-10). At this point, adding the correct position (2,3) obtained from the non-periodic pattern to each periodic position yields (-8,13), (2,13), (12,13), (-8,3), (2,3), (12,3), (-8,-7), (2,-7), and (12,-7). From this added periodic position 1404, the nearest periodic position (12,13) ​​to the detected position (14,15) is identified, so the offset 1405 between (14,15) and (12,13) ​​is found to be (2,2). This offset 1405 is the coordinate error.

[0062] (vi) Step 806 Computer system 2_116 calculates the corrected coordinates by adding the coordinate error obtained in step 805 to the alignment result of the second SEM image. In the specific example in Figure 14, the correct position 1406=(4,5) of the first SEM image is obtained by adding the offset 1405 and the correct position (2,3). This correct position 1406 becomes the corrected coordinates. In this specific example, the periodic shift amount 1407 is the amount of shift from the correct position 1406 to the detected position, and is (4,5)-(14,15)=(-10,-10).

[0063] (vii) Step 807 Computer system 2_116 is step 8Output the correction result or period shift correction result of the first SEM image calculated in step 04 or step 806.

[0064] (3) Summary (i) According to embodiments of the present disclosure, the image data processing system constituting the semiconductor measurement and inspection system 100 comprises a computer system 2_116, a design information database 120, and an input / output device 121. The system performs a first alignment process between the design information of a pattern formation region formed on a sample (wafer) and a first SEM image obtained by imaging at least a part of the pattern formation region to identify first position information of the first SEM image, and performs length measurement or defect inspection of patterns present in the pattern formation region. More specifically, the image data processing system performs a process to acquire periodicity information in the pattern formation region based on the results of autocorrelation processing (maps, distributions, etc.) using the design information, and a process to output or correct the first position information of the first SEM image based on the periodicity information, or to determine whether the first alignment process is successful or not. In this way, even periodic patterns can be aligned to an accurate position, and the design data coordinates corresponding to any location (measurement location or defect location) on the SEM image can be accurately identified. Furthermore, the present invention makes it possible to perform coordinate correction at the end of the measurement and inspection process, eliminating the need for rematching and enabling high-speed correction.

[0065] Computer system 2_116 extracts periodicity information by using a first template 402, which corresponds to part or all of the area of ​​the first SEM image, to search a target area (design data template 401: having an area twice the size of the first template 402) that corresponds to part or all of the area of ​​the autocorrelation processing results (maps, distributions, etc.). Because the search target area is larger than the first template but limited in size, periodicity information can be extracted efficiently, improving throughput. The periodicity information obtained through the above search process can be extracted by moving the first template in the first direction (X direction), the second direction (Y direction), and / or the third direction (diagonal direction). At this time, if the presence of two or more periodic patterns can be identified in the first SEM image, the first SEM image is classified as a periodic pattern. On the other hand, if two or more periodic patterns cannot be identified in the first SEM image, the first SEM image is classified as a non-periodic pattern. Based on the classification results of the first SEM image, the periodicity determination result and, in the case of a periodic pattern, at least one of the matching points or matching interval (period) will be included as parameters in the periodicity information.

[0066] (ii) In the first embodiment of the present disclosure, if the computer system 2_116 can identify the presence of two or more repeating patterns (periodic patterns) in the first SEM image through the search process of the search target area, it identifies the second position information (alignment information with design information) of a unique pattern (non-periodic pattern; second SEM image) that is in the vicinity of the repeating pattern, based on the first position information (alignment information with design information) of the first SEM image and the global position information (wafer coordinates or chip coordinates) attached to the first SEM image, and outputs or corrects the first position information of the first SEM image, or determines whether the first alignment process (alignment process with design information) is good or bad, based on the second position information and periodicity information. In this way, periodic misalignment can be corrected without performing a rematching process.

[0067] Here, global position information (wafer coordinates and chip coordinates) includes imaging position information attached by the imaging device that captured the first and second SEM images, or imaging position information identified by the optical inspection device.

[0068] When correcting the first position information (alignment with design information) of the first SEM image, the computer system 2_116 either uses the second position information (alignment information of the unique pattern) of the second SEM image as the corrected position information (steps 704 and 804), or it calculates a coordinate error from the second position information and the periodicity information of the first SEM image, and determines the corrected position information by adding the coordinate error calculated from the periodicity information to the second position information (see Figures 10 to 14).

[0069] (iii) In a second embodiment of the present disclosure, if the computer system 2_116 identifies the presence of two or more repeating patterns (periodic patterns) in the first SEM image through a search process of the search target area, it identifies a second SEM image which is a non-periodic pattern located in the vicinity of the repeating pattern (periodic pattern) based on the acquisition conditions of the first SEM image and the periodicity information. The computer system 2_116 then identifies second position information which is the result of alignment with the design information of the second SEM image, and outputs or corrects the first position information of the first image, or determines whether the first alignment process is good or bad, based on the second position information and the periodicity information. Specifically, as in the first embodiment, when the computer system 2_116 corrects the first position information (alignment with design information) of the first SEM image, it uses the second position information (alignment information of the unique pattern) of the second SEM image as the corrected position information (steps 704 and 804), or it calculates a coordinate error from the second position information and the periodicity information of the first SEM image, and identifies the corrected position information by adding the coordinate error calculated from the periodicity information to the second position information (see Figures 10 to 14).

[0070] (iv) The functions of each embodiment of the present disclosure can also be realized by software program code. In this case, a storage medium on which the program code is recorded is provided to a system or device, and the computer (or CPU or MPU) of the system or device reads the program code stored on the storage medium. In this case, the program code read from the storage medium itself realizes the functions of the embodiments described above, and the program code itself and the storage medium on which it is stored constitute the present disclosure. Examples of storage media used to supply such program code include flexible disks, CD-ROMs, DVD-ROMs, hard disks, optical disks, magneto-optical disks, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, etc.

[0071] Furthermore, based on the instructions in the program code, the operating system (OS) running on the computer may perform some or all of the actual processing, thereby realizing the functions of the embodiment described above. In addition, after the program code read from the storage medium is written to the computer's memory, the computer's CPU may perform some or all of the actual processing based on the instructions in the program code, thereby realizing the functions of the embodiment described above.

[0072] Furthermore, the program code for the software that realizes the functions of each embodiment may be distributed via a network and stored in a storage means such as a hard disk or memory of the system or device, or in a storage medium such as a CD-RW or CD-R, so that when in use the system or device's computer (or CPU or MPU) reads and executes the program code stored in the storage means or storage medium.

[0073] The processes and technologies described herein are not inherently related to any specific device and can be implemented by combining the components. Various types of general-purpose devices can also be added. Dedicated devices may be constructed to perform the functions of this embodiment and each example. Furthermore, various functions can be formed by appropriately combining the multiple components disclosed in this embodiment and each example. For example, some components may be removed from all the components shown in the embodiment and each example, or components from different embodiments may be appropriately combined.

[0074] This disclosure includes specific examples, which are for illustrative purposes (to understand the technology of this disclosure) and not for limitation in any respect. A person with ordinary skill in the art will understand that there are many combinations of hardware, software, and firmware suitable for implementing the technology of this disclosure. For example, the described software can be implemented in a wide range of programming or scripting languages, such as assembler, C / C++, Perl, Shell, PHP, and Java®.

[0075] Furthermore, in the embodiments described above, the control lines and information lines shown are those deemed necessary for illustrative purposes, and not all control lines and information lines are necessarily shown in the actual product. All components may be interconnected.

[0076] In addition, any person with ordinary skill in the art can see from the consideration of these embodiments and examples that other implementations of this disclosure may be apparent. The specification and examples are typical, and the scope and spirit of the art of this disclosure are shown in the subsequent claims. [Explanation of Symbols]

[0077] 100 Semiconductor measurement and inspection system, 101 Scanning electron microscope, 102 Electron beam column, 103 Electron source, 104 Electron beam, 105 Vacuum sample chamber, 106 Sample stage (XY stage), 107 Sample, 108 Secondary electrons or backscattered electrons, 109 A / D converter, 110 Network 1, 111 Computer system 1, 112 Arithmetic processing unit of computer system 1, 113 Control unit of computer system 1, 114 Storage unit of computer system 1, 115 Network 2, 116 Computer system 2, 117 Arithmetic processing unit of computer system 2, 118 Image processing unit of computer system 2, 119 Storage unit of computer system 2, 120 Design information database, 121 Input / output device (user PC), 401 Design data (having an area twice the FOV of the SEM image), 402 First template used for periodicity determination (same FOV as the SEM image in 403), 403 SEM image for determining the first template used for periodicity determination, 501 Line segment representing the first search direction during periodic search (X direction), 502 Line segment representing the second search direction during periodic search (Y direction), 601 Line segment representing the third search direction during periodic search (diagonal direction), 901 Wafer coordinates, 902 Acquisition position of SEM image with periodic pattern, 903 Acquisition position of SEM image with non-periodic pattern (1), 904 Acquisition position of SEM image with non-periodic pattern (2), 1001 Design data, 1002 Periodicity information (period width), 1003 Periodicity information (period height), 1004 Periodic template, 1005 to 1009 Periodic position (alignment candidate), 1101 to 1104 Periodic position (alignment candidate), 1201 Alignment result, 1202 to 1206 Summarized periodic position, 1301 to 1304 Addition of periodic positions, 1305 Alignment result of identified periodic positions and first SEM image, 1306 Identified periodic positions, 1307 Difference between identified periodic positions 1306 and first SEM image alignment result 1305, 1401 First SEM image (periodic pattern), 1402 Second SEM image (non-periodic pattern), 1403 Periodic position (matching position) list, 1404 Addition of periodic positions (matching position) list, 1405 Offset, 1406 Ground truth position, 1407 Periodic shift amount

Claims

1. A pattern length measurement and defect inspection method, comprising: performing a first alignment process between design information of a pattern formation region formed on a sample and a first image which is a periodic pattern obtained by imaging at least a part of the pattern formation region to identify first position information which is the amount of positional misalignment between the design information and the first image; and performing length measurement or defect inspection of the pattern present in the pattern formation region, A first step is to obtain periodicity information in the pattern formation region based on a map or distribution which is the result of autocorrelation processing using the design information, The second step includes correcting the first position information of the first image based on the periodic information, The first step includes extracting the periodicity information by searching for a search target region corresponding to a part or all of the region of the autocorrelation result using the map or distribution which is the result of the autocorrelation process and a first template which corresponds to a part or all of the region of the first image. method.

2. In claim 1, The second step is a method that, if the search identifies the presence of two or more repeating patterns in the first image, identifies a second position information, which is the amount of positional displacement between a second image, which is a non-periodic pattern in the nearest neighbor to the repeating pattern, and the design information, based on the first position information of the first image and the global position information attached to the first image; and outputs or corrects the first position information of the first image, or determines whether the first alignment process is good or bad, based on the second position information and the periodicity information.

3. In claim 1, The first step is a method comprising: calculating the result of autocorrelation processing using the design information of the first image to obtain a first template; and periodically searching the first template in a first direction and / or a second direction, and / or a third direction to extract periodicity information.

4. In claim 3, A method for extracting the periodic information, which includes setting or updating the periodicity determination result by setting the first image as a periodic pattern if the periodic search identifies the presence of two or more periodic patterns in the first image, and setting the first image as a non-periodic pattern if the two or more periodic patterns cannot be identified.

5. In claim 4, The method includes, for each of the first direction and / or the second direction and / or the third direction, the periodicity determination result and one or more parameters, either the number of matching points or the matching interval in the two or more periodic patterns.

6. In claim 1, A method for correcting the first position information of the first image, which includes correcting the periodic shift of the first image by correcting the first position information using a periodic search process and a coordinate correction process using the periodic information, without performing rematching.

7. In claim 2, The method wherein the global position information includes imaging position information associated with the imaging device that captured the first and second images, or imaging position information identified by an optical inspection device.

8. In claim 2, A method for correcting the first position information of the first image, comprising: setting the second position information as corrected position information; calculating a coordinate error from the second position information and the periodicity information of the first image; and identifying the corrected position information by adding the coordinate error calculated from the periodicity information to the second position information.

9. An image data processing system that performs a first alignment process between design information of a pattern formation region formed on a sample and a first image which is a periodic pattern obtained by imaging at least a part of the pattern formation region to identify first position information which is the amount of positional misalignment between the design information and the first image, and performs length measurement or defect inspection of a pattern present in the pattern formation region, A storage device for storing the aforementioned design information, The system includes a computer system that acquires the design information from the storage device and performs the first alignment process and the length measurement or defect inspection, The aforementioned computer system, A first process involves performing autocorrelation processing using the aforementioned design information and extracting periodicity information in the pattern formation region based on the map or distribution resulting from the autocorrelation processing. A second process is performed to correct the first position information of the first image based on the periodicity information, Execute, In the second process, if the computer system can identify the existence of two or more repeating patterns in the first image through the search process in the autocorrelation process, it performs the following processes: identifying second position information, which is the amount of positional displacement between the second image, which is a non-periodic pattern in the nearest neighbor to the repeating pattern, and the design information, based on the first position information of the first image and the global position information attached to the first image; and outputting or correcting the first position information of the first image, or determining whether the first alignment process is successful, based on the second position information and the periodicity information. Image data processing system.

10. In claim 9, The computer system is an image data processing system that, when correcting the first position information of the first image, performs the following processes: setting the second position information as corrected position information, or calculating a coordinate error from the second position information and the periodicity information of the first image, and identifying the corrected position information by adding the coordinate error calculated from the periodicity information to the second position information.

11. In claim 9, The computer system is an image data processing system that, when correcting the first position information of the first image, corrects the first position information by performing a periodic search process and a coordinate correction process using the periodic information, without rematching, thereby correcting the periodic shift of the first image.

12. In claim 9, The image data processing system includes, for example, global location information, imaging location information associated with an imaging device that captured the first and second images, or imaging location information identified by an optical inspection device.

13. A computer-readable recording medium for recording a program that causes a computer to perform a pattern length measurement or defect inspection method, The pattern length measurement or defect inspection method is a method for measuring the length of a pattern or inspecting defects in a pattern present within the pattern formation region by performing a first alignment process between design information of a pattern formation region formed on a sample and a first image which is a periodic pattern obtained by imaging at least a part of the pattern formation region, thereby identifying first position information which is the amount of positional misalignment between the design information and the first image, and performing a first alignment process between design information of a pattern formation region formed on a sample and a first image which is a periodic pattern obtained by imaging at least a part of the pattern formation region, To obtain periodicity information in the pattern formation region based on a map or distribution which is the result of autocorrelation processing using the aforementioned design information, Based on the periodicity information, the first position information of the first image is corrected, Includes, Acquiring the periodicity information includes extracting the periodicity information by searching for a search target region corresponding to a part or all of the region of the autocorrelation processing result using the map or distribution which is the result of the autocorrelation processing, and a first template which corresponds to a part or all of the region of the first image. A computer-readable recording medium.

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