Pattern measurement method and pattern measurement device

Abstract

The pattern measurement method connects an extension line (105) of a prescribed length to an end of a first CAD edge (101a) of a first CAD pattern (101), determines a second CAD pattern (102) having a second CAD edge (102a) existing within a prescribed search range in a normal direction from the extension line (105), acquires first pattern information including a number of a layer to which the first CAD pattern (101) belongs and second pattern information including a number of a layer to which the second CAD pattern (102) belongs from design data, detects a first actual edge (201a) and a second actual edge (202a) on an image (200) using edge detection parameters, and measures a distance (L) in the normal direction of the first actual edge (201a) and the second actual edge (202a).

Description

Technical Field

[0001] This invention relates to a technique for measuring the distance between patterns formed on workpieces such as wafers, masks, panels, and substrates, and particularly to a technique for measuring the distance between patterns on images generated by an image generating device such as a scanning electron microscope. Background Technology

[0002] Wafers, masks, panels, substrates, and other workpieces have multi-layered surface structures, with multiple patterns formed in the multiple layers within these structures. To inspect the patterns formed on the workpieces, images of the patterns are generated using a scanning electron microscope, and the distances between the patterns in the images are measured.

[0003] Recently, the accelerating voltage of the electron beam in a scanning electron microscope has sometimes been increased, generating images not only of the outermost layer but also of the layers beneath it. Images generated under such high accelerating voltage conditions, such as... Figure 10 As shown, multiple patterns overlap within multiple layers. Figure 10 In the image 500 shown, pattern 501 is located in the first layer, pattern 502 is located in the second layer below the first layer, and pattern 503 is located in the third layer below the second layer.

[0004] Pattern 501 in the first layer is made of a material that does not transmit electron beams, while pattern 502 in the second layer is made of a material that transmits electron beams. Therefore, part of pattern 503 in the third layer is obscured by pattern 501 and cannot be seen, but another part of pattern 503 is visible through pattern 502.

[0005] When measuring the distance between patterns on image 500, several ROIs (regions of interest) are defined on image 500. Figure 10 In this context, ROI1 is set to measure the length of the portion of pattern 501 that protrudes from pattern 503. ROI2 is set to measure the distance between pattern 501 and pattern 502.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2009-243993 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] In ROI1, the distance between edge 501a of pattern 501 and edge 503a of pattern 503 is measured. Therefore, before distance measurement, edges 501a and 503a on image 500 are first detected based on brightness variations within image 500. Since pattern 501 is composed of a non-transmissive material, edge 503a of pattern 503 will not appear on image 500 in the overlapping portion of pattern 501 and pattern 503. Therefore, as... Figure 10 As shown, the edge 503a of pattern 503 located outside pattern 501 is detected.

[0011] Figure 11 This diagram illustrates an example of a method for measuring the distance between edges 501a and 503a on image 500. The position of the intersection point P501 of the brightness profile BP501 of edge 501a and the edge threshold represents the position of edge 501a. The position of the intersection point P503 of the brightness profile BP503 of edge 503a and the edge threshold represents the position of edge 503a. The distance L between edges 501a and 503a can be calculated based on the positions of the intersection points P501 and P503.

[0012] However, the position of the edge 503a of pattern 503 is easily affected by the brightness of adjacent patterns 501 within ROI1. For example, Figure 12 This shows pattern 501 within ROI1 and Figure 11 The example is compared to a coarser example. In this example, the brightness profile BP503 of edge 503a varies due to the brightness of pattern 501. The position of the intersection point P503 of the brightness profile BP503 of edge 503a and the edge threshold also changes due to the variation of the brightness profile BP503. As a result, the distance L between edge 501a and edge 503a is not measured correctly.

[0013] exist Figure 10 In the shown ROI2, the distance between edge 501b of pattern 501 and edge 502a of pattern 502 is measured. Therefore, before distance measurement, edges 501b and 502a on image 500 are first detected based on brightness changes within image 500. Specifically, as... Figure 13 As shown, a brightness profile traversing ROI2 is generated, and the positions P1 of edge 501b and P2 of edge 502a are determined as the intersection of the edge detection threshold and the brightness profile.

[0014] On image 500, it's impossible to distinguish that patterns 501 and 502 belong to different layers, so the same edge detection threshold is used. However, the edge detection threshold suitable for the first layer to which pattern 501 belongs is usually different from the edge detection threshold suitable for the second layer to which pattern 502 belongs. Therefore, if the same edge detection threshold is used, sometimes the position P1 of edge 501b or the position P2 of edge 502a cannot be detected correctly. As a result, the distance between edges 501b and 502a may not be measured correctly.

[0015] Therefore, the present invention provides a technique for obtaining pattern information from design data and accurately measuring the distance between patterns on an image based on that information.

[0016] Problem-solving methods

[0017] In one approach, a pattern measurement method is provided for measuring the distance between multiple patterns on an image. This involves connecting an extension line of a predetermined length to the end of a first CAD edge of a first CAD pattern, determining a second CAD pattern having a second CAD edge existing within a predetermined search range along the normal direction from the extension line, obtaining first pattern information containing the layer number to which the first CAD pattern belongs and second pattern information containing the layer number to which the second CAD pattern belongs from design data, detecting a first actual edge and a second actual edge on the image corresponding to the first CAD edge and the second CAD edge using edge detection parameters, and measuring the distance between the first actual edge and the second actual edge in the normal direction.

[0018] In one embodiment, the layer to which the second CAD pattern belongs is different from the layer to which the first CAD pattern belongs.

[0019] In one embodiment, the second CAD pattern belongs to the same layer as the first CAD pattern.

[0020] In one embodiment, the edge detection parameters include a first edge detection parameter pre-set for the layer to which the first CAD pattern belongs, and a second edge detection parameter pre-set for the layer to which the second CAD pattern belongs.

[0021] In one approach, the edge detection parameters include the peak search range and valley search range of the brightness profile of the actual pattern, and the edge detection threshold on the brightness profile.

[0022] In one embodiment, the pattern measurement method further includes: assigning direction information to a plurality of CAD edges constituting the first CAD pattern and the second CAD pattern according to a prescribed rule; and assigning a line width, spacing, or pitch to a group of the first actual edges and the second actual edges based on the direction information indicating the direction of the first CAD edge and the direction of the second CAD edge.

[0023] In one approach, when the direction of the first CAD edge is a first direction and the direction of the second CAD edge is a second direction opposite to the first direction, a line width attribute is assigned to the group of the first actual edge and the second actual edge; when the direction of the first CAD edge is the second direction and the direction of the second CAD edge is the first direction, a spacing attribute is assigned to the group of the first actual edge and the second actual edge; and when both the direction of the first CAD edge and the direction of the second CAD edge are either the first direction or the second direction, a pitch attribute is assigned to the group of the first actual edge and the second actual edge.

[0024] In one embodiment, the layer to which the second CAD pattern belongs is located below the layer to which the first CAD pattern belongs, and the pattern measurement method further includes: designating the first CAD pattern and the second CAD pattern as either a transmissive pattern or a non-transmissive pattern.

[0025] In one embodiment, a pattern measuring apparatus is provided for measuring the distance between multiple patterns on an image. This apparatus includes a storage device storing a program and design data, and a computing device that performs calculations according to commands contained in the program. The program is configured to cause the computing device to perform the following actions: connecting an extension line of a predetermined length to the end of a first CAD edge of a first CAD pattern; determining a second CAD pattern having a second CAD edge, the second CAD edge existing within a predetermined search range along the normal direction from the extension line; obtaining first pattern information containing the layer number to which the first CAD pattern belongs and second pattern information containing the layer number to which the second CAD pattern belongs from the design data; detecting a first actual edge and a second actual edge on the image corresponding to the first CAD edge and the second CAD edge using edge detection parameters; and measuring the distance between the first actual edge and the second actual edge in the normal direction.

[0026] In one embodiment, the layer to which the second CAD pattern belongs is different from the layer to which the first CAD pattern belongs.

[0027] In one embodiment, the second CAD pattern belongs to the same layer as the first CAD pattern.

[0028] In one embodiment, the edge detection parameters include a first edge detection parameter pre-set for the layer to which the first CAD pattern belongs, and a second edge detection parameter pre-set for the layer to which the second CAD pattern belongs.

[0029] In one approach, the edge detection parameters include the peak search range and valley search range of the brightness profile of the actual pattern, and the edge detection threshold on the brightness profile.

[0030] In one embodiment, the program is configured to cause the computing device to perform the following actions: assigning direction information to a plurality of CAD edges constituting the first CAD pattern and the second CAD pattern according to a predetermined rule, and assigning a line width, spacing, or pitch to a group of the first actual edges and the second actual edges based on the direction information of the first CAD edge and the direction of the second CAD edge.

[0031] In one embodiment, the program is configured to cause the computing device to perform the following actions: when the direction of the first CAD edge is a first direction and the direction of the second CAD edge is a second direction opposite to the first direction, assigning a line width attribute to the group of the first actual edge and the second actual edge; when the direction of the first CAD edge is the second direction and the direction of the second CAD edge is the first direction, assigning a spacing attribute to the group of the first actual edge and the second actual edge; and when both the direction of the first CAD edge and the direction of the second CAD edge are the first direction or the second direction, assigning a pitch attribute to the group of the first actual edge and the second actual edge.

[0032] In one embodiment, the layer to which the second CAD pattern belongs is located below the layer to which the first CAD pattern belongs, and the program is configured to cause the computing device to perform the following action: designate the first CAD pattern and the second CAD pattern as either a transmissive pattern or a non-transmissive pattern.

[0033] Invention Effects

[0034] According to the present invention, information (relative positions between edges, layers, etc.) of a first CAD pattern and a second CAD pattern corresponding to the actual pattern to be measured can be obtained from the design data. Based on this information, the distance between the patterns can be measured correctly. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating one embodiment of an image generation apparatus.

[0036] Figure 2 This is a schematic diagram illustrating an example of a CAD pattern included in design data.

[0037] Figure 3 This is a schematic diagram illustrating an example of an image showing a first actual pattern and a second actual pattern corresponding to a first CAD pattern and a second CAD pattern.

[0038] Figure 4 This is a diagram illustrating one implementation of the process for detecting the first actual edge.

[0039] Figure 5 This is a schematic diagram illustrating an example of an image showing a third actual pattern existing between a first actual pattern and a second actual pattern.

[0040] Figure 6 This is a schematic diagram illustrating an example of multiple CAD patterns belonging to the same layer arranged in an interlaced manner.

[0041] Figure 7 This is a schematic diagram illustrating the action of assigning directional information to the multiple CAD edges that constitute the first CAD pattern and the second CAD pattern, respectively.

[0042] Figure 8 It is a diagram illustrating the attributes of line width, spacing, and pitch.

[0043] Figure 9 This is a schematic diagram illustrating an example of an image of an actual pattern formed within three layers.

[0044] Figure 10 This is a schematic diagram illustrating an example of an image in which multiple patterns overlap within multiple layers.

[0045] Figure 11 This is a diagram illustrating an example of a conventional method for measuring the distance between two edges on an image.

[0046] Figure 12 This is a diagram illustrating an example of how the distance between two edges changes depending on the shape of the pattern.

[0047] Figure 13 It is shown Figure 10 An example of the brightness profile within ROI2 is shown in the figure. Detailed Implementation

[0048] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1This is a schematic diagram illustrating one embodiment of the image generation apparatus. The image generation apparatus includes a scanning electron microscope 1 for generating an image of a workpiece W, and a pattern measuring device 5 for measuring the distance between patterns on the image generated by the scanning electron microscope 1. Examples of workpiece W include wafers, masks, panels, substrates, etc., used in the manufacture of semiconductor devices.

[0049] The pattern measuring device 5 comprises at least one computer. The pattern measuring device 5 includes a storage device 5a storing a program and a processing device 5b executing operations according to commands contained in the program. The storage device 5a includes a main storage device such as RAM and an auxiliary storage device such as a hard disk drive (HDD) or a solid-state drive (SSD). Examples of the processing device 5b include a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). However, the specific configuration of the pattern measuring device 5 is not limited to these examples.

[0050] The pattern measuring device 5 can be an edge server connected to the scanning electron microscope 1 via a communication line, a cloud server connected to the scanning electron microscope 1 via a communication network such as the Internet or a local area network, or a fog computing device (gateway, fog server, router, etc.) set up in a network connected to the scanning electron microscope 1. The pattern measuring device 5 can also be a combination of multiple servers. For example, the pattern measuring device 5 can be a combination of edge servers and cloud servers interconnected via a communication network such as the Internet or a local area network.

[0051] The scanning electron microscope 1 includes an electron gun 15 that emits an electron beam, a converging lens 16 that converges the electron beam emitted from the electron gun 15, an X-deflector 17 that deflects the electron beam in the X direction, a Y-deflector 18 that deflects the electron beam in the Y direction, an objective lens 20 that focuses the electron beam onto a workpiece W, which is an example of a sample, and a stage 31 that supports the workpiece W. The configuration of the electron gun 15 is not particularly limited. For example, a field emission type electron gun or a semiconductor photocathode type electron gun can be used as the electron gun 15.

[0052] The electron beam emitted from the electron gun 15 is focused by the converging lens 16, deflected by the X deflector 17 and Y deflector 18, and then focused by the objective lens 20 to irradiate the surface of the workpiece W. When the workpiece W is irradiated with primary electrons from the electron beam, secondary electrons and reflected electrons are emitted from the workpiece W. The emitted electrons are detected by the electron detector 26. The electron detection signal from the electron detector 26 is input to the image acquisition device 28 and converted into an image. Thus, the scanning electron microscope 1 generates an image of the surface of the workpiece W. The image acquisition device 28 is connected to the pattern measuring device 5, and the image of the workpiece W is sent to the pattern measuring device 5.

[0053] The following describes a method for measuring the distance between patterns on an image generated by a scanning electron microscope 1. In the following description, the patterns on the workpiece W are formed based on design data (also known as CAD data). CAD is an abbreviation for computer-aided design.

[0054] The design data of the pattern formed on the workpiece W is pre-stored in the storage device 5a. The design data includes information about the pattern, such as the coordinates of the vertices of the pattern formed on the workpiece W, the position, shape, and size of the pattern, and the layer number to which the pattern belongs. The motion control unit 5 can read the design data of the pattern from the storage device 5a.

[0055] The CAD patterns included in the design data described below are virtual patterns defined by the information contained in the design data and have polygonal shapes. In the following description, the pattern that is actually formed on the workpiece W and appears in the image is sometimes referred to as the actual pattern.

[0056] Figure 2 This is a schematic diagram illustrating an example of CAD patterns included in design data. First CAD pattern 101 belongs to the first layer, and second CAD pattern 102 belongs to the second layer. The first and second layers are different layers; the second layer exists below the first layer. The second layer can also exist above the first layer.

[0057] The pattern measuring device 5 connects an extension line 105 of a predetermined length to the end of the first CAD edge 101a of the first CAD pattern 101. The length direction of the extension line 105 is consistent with the length direction of the first CAD edge 101a. The length of the extension line 105 is not particularly limited, but the length of the extension line 105 is sometimes less than the length of the first CAD edge 101a, or sometimes more than the length of the first CAD edge 101a.

[0058] The pattern measuring device 5 determines a defined search range S centered on the extension line 105. The search direction of the search range S is a normal direction relative to the extension line 105 and the first CAD edge 101a (i.e., perpendicular to the extension line 105 and the first CAD edge 101a). The pattern measuring device 5 searches within the search range S from the extension line 105 along the normal direction and determines a second CAD pattern 102 having a second CAD edge 102a present within the search range S.

[0059] The pattern measuring device 5 obtains first pattern information, including the layer number to which the first CAD pattern 101 belongs, and second pattern information, including the layer number to which the second CAD pattern 102 belongs, from the design data. The first pattern information includes the coordinates of the vertices of the first CAD pattern 101, the position, shape, and size of the first CAD pattern 101, and the layer number to which the first CAD pattern 101 belongs. The second pattern information includes the coordinates of the vertices of the second CAD pattern 102, the position, shape, and size of the second CAD pattern 102, and the layer number to which the second CAD pattern 102 belongs.

[0060] Figure 3 This is a schematic diagram illustrating an example of an image 200 showing a first actual pattern 201 and a second actual pattern 202 corresponding to a first CAD pattern 101 and a second CAD pattern 102. The scanning electron microscope 1 generates an image 200 of the first actual pattern 201 and the second actual pattern 202 corresponding to the first CAD pattern 101 and the second CAD pattern 102, and the pattern measuring device 5 acquires the image 200 from the scanning electron microscope 1.

[0061] The pattern measuring device 5 uses edge detection parameters to detect the first actual edge 201a and the second actual edge 202a on the image 200 corresponding to the first CAD edge 101a and the second CAD edge 102a, and measures the distance L between the first actual edge 201a and the second actual edge 202a in the normal direction. This normal direction is perpendicular to... Figure 2 The direction of the extension line 105 (and the first CAD edge 101a) shown.

[0062] According to this embodiment, even when the first actual edge 201a and the second actual edge 202a are not opposite to each other, the pattern measuring device 5 can still be used as described above. Figure 2 As explained, based on pattern information (relative position between edges, layer number, etc.) about the first CAD pattern 101 and the second CAD pattern 102, the distance L between the first actual edge 201a and the second actual edge 202a in the normal direction is measured.

[0063] Next, an implementation of detecting a first actual edge 201a and a second actual edge 202a on image 200 using edge detection parameters will be described. Since the first actual edge 201a and the second actual edge 202a are detected using the same edge detection method (algorithm), the detection of the first actual edge 201a will be described below.

[0064] The edge detection parameters include the peak search range and valley search range of the brightness profile of the first actual pattern 201, and the edge detection threshold on the brightness profile. In this embodiment, the edge detection parameters further include the number of multiple brightness profiles of the first actual pattern 201 used to create the brightness profile of the first actual pattern 201. In this embodiment, the brightness profile of the first actual pattern 201 is the average of multiple brightness profiles.

[0065] Figure 4 This diagram illustrates one embodiment of the process for detecting the first actual edge 201a of the first actual pattern 201. The pattern measuring device 5 generates multiple brightness profiles 300 on multiple edge search lines SR1 to SR5, including an edge search line SR3 perpendicular to the first actual edge 201a. The edge search line SR3 is located at the center of the multiple edge search lines SR1 to SR5. The multiple brightness profiles 300 represent the distribution of brightness values ​​of pixels on the multiple search lines SR1 to SR5 perpendicular to the first actual edge 201a. The pattern measuring device 5 generates an average brightness profile by accumulating the multiple brightness profiles 300 and dividing the resulting accumulated profile by the number of brightness profiles 300. This average brightness profile is the brightness profile on the edge search line SR3.

[0066] The number of brightness profiles 300 used to generate the average brightness profile is one of the edge detection parameters. Figure 4 In this embodiment, five brightness profiles 300 are used. However, the number of brightness profiles 300 is not limited to this embodiment. In one embodiment, the number of brightness profiles 300 used as one of the edge detection parameters may be one. In this case, the brightness profile on the edge search line SR3 is used directly, and an average brightness profile is not generated.

[0067] Next, the pattern measuring device 5 determines the peak search range RA1 and the valley search range RA2 of the brightness profile on the edge search line SR3. The peak search range RA1 defines the range for finding the peak point P on the brightness profile, and the valley search range RA2 defines the range for finding the valley point B on the brightness profile.

[0068] like Figure 4 As shown, the peak search range RA1 is determined based on the position C of the first CAD edge 101a of the first CAD pattern 101. Specifically, the peak search range RA1 is a range of a predetermined width centered on the position C of the first CAD edge 101a. The pattern measuring device 5 determines the point P, i.e., the peak point, on the luminance contour with the highest luminance value within the peak search range RA1. The valley search range RA2 is a range of a predetermined width with the position of the peak point P as the lower limit. The pattern measuring device 5 determines the point B, i.e., the valley point, on the luminance contour with the lowest luminance value within the valley search range RA2.

[0069] The pattern measuring device 5 reads a pre-set edge detection threshold for the first layer to which the first CAD pattern 101 belongs from the storage device 5a, and uses this edge detection threshold to determine the position of the first actual edge 201a on the edge search line SR3. That is, as Figure 4 As shown, the pattern measuring device 5 determines the position of the intersection point E of the brightness profile and the edge detection threshold, and uses the position of the intersection point E as the position of the first actual edge 201a on the edge search line SR3. The pattern measuring device 5 determines the overall position of the first actual edge 201a by repeating the same operation while changing the positions of the edge search lines SR1 to SR5 on the first actual edge 201a. The pattern measuring device 5 also detects... Figure 3 The second actual edge 202a of the second actual pattern 202 shown.

[0070] Because the pattern measuring device 5 is in reference Figure 2 During the pattern search process described, information about the layers to which the first actual pattern 201 and the second actual pattern 202 belong is obtained, allowing the use of pre-set optimal edge detection thresholds for each layer. Specifically, the detection of the first actual edge 201a belonging to the first layer uses the first edge detection threshold, and the detection of the second actual edge 202a belonging to the second layer uses the second edge detection threshold. Therefore, the pattern measuring device 5 can correctly detect the first actual edge 201a and the second actual edge 202a, resulting in the accurate measurement of the distance L between the first actual edge 201a and the second actual edge 202a.

[0071] Figure 5 This is a schematic diagram illustrating an example of an image showing a third actual pattern 203 existing between a first actual pattern 201 and a second actual pattern 202. The third actual pattern 203 is a pattern that is not the object being measured. The third actual pattern 203 is, for example, a pattern existing in a third layer below the second layer. The presence of such a third actual pattern 203 may constitute noise in the edge detection of the first actual pattern 201 and the second actual pattern 202.

[0072] That is, such as Figure 5 As shown, the brightness profile BP1 on search line SR11 includes not only the brightness of the first actual pattern 201, but also the brightness of the third actual pattern 203. Similarly, the brightness profile BP2 on search line SR12 includes not only the brightness of the second actual pattern 202, but also the brightness of the third actual pattern 203. The brightness of the third actual pattern 203 included in brightness profiles BP1 and BP2 may hinder the correct detection of the edges of the first and second actual patterns 201.

[0073] Therefore, the pattern measuring device 5, based on the pattern information of the corresponding first CAD pattern 101 and the pattern information of the corresponding second CAD pattern 102, limits the search range of the edges 201a and 202a of the first actual pattern 201 and the second actual pattern 202. Specifically, the pattern measuring device 5 limits the search range of the edges 201a and 202a of the reference pattern 201. Figure 4 The lengths of search lines SR1 to SR5 are explained.

[0074] Pattern measuring device 5 at reference Figure 2 During the pattern search process described, the position information of the third CAD pattern corresponding to the third actual pattern 203 is acquired. Based on the position information of the first CAD pattern 101 and the third CAD pattern, the pattern measuring device 5 limits the search range of the edge 201a of the first actual pattern 201. Similarly, based on the position information of the second CAD pattern 102 and the third CAD pattern, the pattern measuring device 5 limits the edge search range of the edge 202a of the second actual pattern 202. As a result, the brightness contours BP1 and BP2 do not include the brightness of the third actual pattern 203. Therefore, the pattern measuring device 5 can correctly detect the edges 201a and 202a of the first actual pattern 201 and the second actual pattern 202.

[0075] In reference Figures 2 to 5 In the described embodiments, the first CAD pattern 101 (first actual pattern 201) and the second CAD pattern 102 (second actual pattern 202) belong to different layers. However, in one embodiment, the first CAD pattern 101 (first actual pattern 201) and the second CAD pattern 102 (second actual pattern 202) may belong to the same layer. For example, in Figure 6 In this configuration, multiple CAD patterns 301 and 302 belonging to the same layer are arranged in an alternating pattern. In this case, the pattern measuring device 5 can also measure according to a reference... Figure 2 The pattern search action described determines the CAD edges 301a and 302a of the measured object and correctly measures the distance between the corresponding actual edges on the image.

[0076] Typically, there are numerous measurement points for the distance between patterns set on a workpiece. Therefore, in order to easily manage the distance measurement results, in the embodiment described below, the pattern measuring device 5 classifies the actual edges of the measured object into one of line width, spacing, or pitch according to their attributes, and outputs the distance measurement value and one of the attributes of line width, spacing, or pitch. This embodiment will be described in detail below.

[0077] like Figure 7As shown, the pattern measuring device 5 assigns direction information to the plurality of CAD edges constituting the first CAD pattern 101 and the second CAD pattern 102, respectively. The direction information is assigned to the plurality of CAD edges according to a predetermined rule. In one embodiment, the predetermined rule is to assign the direction in a clockwise or counterclockwise direction. For example, as... Figure 7 As indicated by the arrows, the pattern measuring device 5 assigns a clockwise direction to the plurality of CAD edges constituting the first CAD pattern 101 and the second CAD pattern 102, respectively. In one embodiment, the rule is to assign either a clockwise or counterclockwise direction depending on the type of CAD pattern. For example, a clockwise direction is assigned to the CAD edges of a CAD island pattern, and a counterclockwise direction is assigned to the CAD edges of a CAD hole pattern.

[0078] The pattern measuring device 5 determines one of the attributes, such as line width, spacing, or pitch, based on the combination of the directions of the two CAD edges that are the objects of distance measurement, and assigns the attribute to the group of two actual edges corresponding to the two CAD edges.

[0079] Figure 8 This is a diagram illustrating the attributes of line width, spacing, and pitch. Line width is an attribute when the directions of the two CAD edges, which are the objects of distance measurement, are opposite. That is, when the direction of the CAD edge of the first CAD pattern 101 is a first direction and the direction of the CAD edge of the second CAD pattern 102 is a second direction opposite to the first direction, the pattern measuring device 5 assigns the attribute of line width to the group of two actual edges corresponding to these two CAD edges.

[0080] Spacing is an attribute that occurs when the directions of the two CAD edges of the distance measurement object are opposite to each other and are opposite to the row width attribute. That is, when the direction of the CAD edge of the first CAD pattern 101 is the second direction and the direction of the CAD edge of the second CAD pattern 102 is the first direction, the pattern measuring device 5 assigns the spacing attribute to the group of two actual edges corresponding to these two CAD edges.

[0081] Pitch is an attribute that occurs when the directions of the two CAD edges of the distance measurement object are the same. That is, when the direction of the CAD edge of the first CAD pattern 101 and the direction of the CAD edge of the second CAD pattern 102 are both the first direction or the second direction, the pattern measuring device 5 assigns the pitch attribute to the group of two actual edges corresponding to these two CAD edges.

[0082] The pattern measuring device 5 associates the attributes of a group of two actual edges of the object being measured with the measured value of the distance between these actual edges. The measured value of the distance between the actual edges, together with the associated attributes, is stored in the storage device 5a.

[0083] Figure 9 This is a schematic diagram illustrating an example of an actual pattern formed within three layers. Figure 9 In the example shown, a first actual pattern 401, a second actual pattern 402, and a third actual pattern 403 appear in image 400. The first actual pattern 401 is located in the first layer, the second actual pattern 402 is located in the second layer, and the third actual pattern 403 is located in the third layer. The first actual pattern 401 and the third actual pattern 403 are non-transmissive patterns made of non-transmissive material that does not allow electron beams to pass through, while the second actual pattern 402 is a transmissive pattern made of transmissive material that allows electron beams to pass through.

[0084] Whether a pattern allows an electron beam to pass through depends on the material constituting the pattern, the pattern thickness, and the accelerating voltage of the electron beam. For example, metals are difficult for electron beams to pass through, while polycrystalline silicon and insulating materials (such as SiO2) do. The pattern measuring device 5 designates one of the multiple CAD patterns included in the design data as either a transmissive or non-transmissive pattern based on factors such as the material constituting the pattern, the pattern thickness, and the accelerating voltage of the electron beam.

[0085] exist Figure 9 In the example shown, the CAD pattern corresponding to the first actual pattern 401 and the third actual pattern 403 is designated as a non-transparent pattern, while the CAD pattern corresponding to the second actual pattern 402 is designated as a transmissive pattern. In other examples, Figure 3 The first CAD pattern 101 shown is designated as a non-transparent pattern, and the second CAD pattern 102 is designated as a transmissive pattern.

[0086] To measure the distance between actual patterns, the actual patterns must appear in the image. Whether the actual pattern, which is the object of distance measurement, appears in the image can be determined based on the position, area, and whether it is a transmissive or non-transmissive pattern of the CAD pattern in each layer.

[0087] The above embodiments are described with the aim of enabling those skilled in the art to implement the present invention. Various modifications of the above embodiments can, of course, be made by those skilled in the art, and the technical concept of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be interpreted in the broadest sense according to the technical concept defined by the claims.

[0088] Industrial availability

[0089] This invention can be used to measure the distance between patterns formed on workpieces such as wafers, masks, panels, and substrates, and in particular, it can be used to measure the distance between patterns on images generated by image generation devices such as scanning electron microscopes.

[0090] Label Explanation

[0091] 1. Scanning electron microscope

[0092] 5. Motion Control Unit

[0093] 15 Electron Guns

[0094] 16 Converging Lenses

[0095] 17 X deflector

[0096] 18 Y deflector

[0097] 20 Objective lenses

[0098] 26 Electronic detectors

[0099] 31. Platform

[0100] 101 First CAD Pattern

[0101] 101a First CAD Edge

[0102] 102 Second CAD Pattern

[0103] 102a Second CAD Edge

[0104] 105 extension line

[0105] 200 images

[0106] 201 First Actual Pattern

[0107] 201a First Real Edge

[0108] 202 Second Actual Pattern

[0109] 202a Second Real Edge

[0110] CAD patterns 301 and 302

[0111] 400 images

[0112] 401 First Actual Pattern

[0113] 402 Second Actual Pattern

[0114] 403 Third Actual Pattern

[0115] SR1~SR5, SR11, SR12 Edge search lines

[0116] RA1 Peak Search Range

[0117] RA2 Valley search range.

Claims

1. A pattern measurement method for measuring the distance between multiple patterns on an image, characterized in that, Connect an extension line of a specified length to the end of the first CAD edge of the first CAD pattern. A second CAD pattern with a second CAD edge is determined, the second CAD edge existing within a specified search range from the extension line along the normal direction. Obtain first pattern information, which includes the layer number to which the first CAD pattern belongs, and second pattern information, which includes the layer number to which the second CAD pattern belongs, from the design data. Edge detection parameters are used to detect the first and second actual edges on the images corresponding to the first CAD edge and the second CAD edge. Measure the distance between the first actual edge and the second actual edge in the normal direction.

2. The pattern measurement method according to claim 1, characterized in that, The second CAD pattern belongs to a different layer than the first CAD pattern.

3. The pattern measurement method according to claim 1, characterized in that, The second CAD pattern belongs to the same layer as the first CAD pattern.

4. The pattern measurement method according to claim 2, characterized in that, The edge detection parameters include a first edge detection parameter preset for the layer to which the first CAD pattern belongs, and a second edge detection parameter preset for the layer to which the second CAD pattern belongs.

5. The pattern measurement method according to claim 1, characterized in that, The edge detection parameters include the peak search range and valley search range of the brightness contour of the actual pattern, and the edge detection threshold on the brightness contour.

6. The pattern measurement method according to claim 1, characterized in that, Further includes, According to the prescribed rules, directional information is assigned to the multiple CAD edges that constitute the first CAD pattern and the second CAD pattern, respectively. Based on the direction of the first CAD edge and the direction of the second CAD edge as indicated by the direction information, assign one of the following attributes to the group of the first actual edge and the second actual edge: line width, spacing, or pitch.

7. The pattern measurement method according to claim 6, characterized in that, When the direction of the first CAD edge is a first direction and the direction of the second CAD edge is a second direction opposite to the first direction, a line width attribute is assigned to the group of the first actual edge and the second actual edge. When the direction of the first CAD edge is the second direction, and the direction of the second CAD edge is the first direction, a spacing attribute is assigned to the group of the first actual edge and the second actual edge. When both the direction of the first CAD edge and the direction of the second CAD edge are either the first direction or the second direction, a pitch attribute is assigned to the group of the first actual edge and the second actual edge.

8. The pattern measurement method according to claim 2, characterized in that, The layer to which the second CAD pattern belongs is below the layer to which the first CAD pattern belongs. It further includes designating the first CAD pattern and the second CAD pattern as either a transmissive pattern or a non-transmissive pattern.

9. A pattern measuring device for measuring the distance between multiple patterns on an image, characterized in that, have: Storage devices that store program and design data; and An arithmetic device that performs calculations according to commands contained in the program. The program is configured to cause the computing device to perform the following actions: Connect an extension line of a specified length to the end of the first CAD edge of the first CAD pattern. A second CAD pattern with a second CAD edge is determined, which exists within a predetermined search range from the extension line along the normal direction. Obtain first pattern information containing the layer number to which the first CAD pattern belongs, and second pattern information containing the layer number to which the second CAD pattern belongs from the design data. Edge detection parameters are used to detect the first and second actual edges on the images corresponding to the first CAD edge and the second CAD edge. Measure the distance between the first actual edge and the second actual edge in the normal direction.

10. The pattern measuring device according to claim 9, characterized in that, The second CAD pattern belongs to a different layer than the first CAD pattern.

11. The pattern measuring device according to claim 9, characterized in that, The second CAD pattern belongs to the same layer as the first CAD pattern.

12. The pattern measuring device according to claim 10, characterized in that, The edge detection parameters include a first edge detection parameter preset for the layer to which the first CAD pattern belongs, and a second edge detection parameter preset for the layer to which the second CAD pattern belongs.

13. The pattern measuring device according to claim 9, characterized in that, The edge detection parameters include the peak search range and valley search range of the brightness contour of the actual pattern, and the edge detection threshold on the brightness contour.

14. The pattern measuring device according to claim 9, characterized in that, The program is configured to cause the computing device to perform the following actions: According to the prescribed rules, directional information is assigned to the multiple CAD edges that constitute the first CAD pattern and the second CAD pattern, respectively. Based on the direction of the first CAD edge and the direction of the second CAD edge as indicated by the direction information, assign one of the following attributes to the group of the first actual edge and the second actual edge: line width, spacing, or pitch.

15. The pattern measuring device according to claim 14, characterized in that, The program is configured to cause the computing device to perform the following actions: When the direction of the first CAD edge is a first direction and the direction of the second CAD edge is a second direction opposite to the first direction, a line width attribute is assigned to the group of the first actual edge and the second actual edge. When the direction of the first CAD edge is the second direction, and the direction of the second CAD edge is the first direction, a spacing attribute is assigned to the group of the first actual edge and the second actual edge. When both the direction of the first CAD edge and the direction of the second CAD edge are either the first direction or the second direction, a pitch attribute is assigned to the group of the first actual edge and the second actual edge.

16. The pattern measuring device according to claim 10, characterized in that, The layer to which the second CAD pattern belongs is below the layer to which the first CAD pattern belongs. The program is configured to cause the computing device to perform the following action: designate the first CAD pattern and the second CAD pattern as either a transmissive pattern or a non-transmissive pattern.

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