A method for mask defect detection based on a circular detection area

Abstract

The application discloses a kind of mask defect detection methods based on circular detection area, is realized using a mask defect detection system, and mask defect detection system contains detection camera and motion platform of loading mask, the steps of method contain: setting the feature pattern of alignment on mask design drawing and selecting circular detection area by the way of specifying center (gx0,gy0) and radius r;After loading mask on motion platform, the mapping relationship of motion platform coordinates and the coordinates of mask design drawing is established by detecting camera on motion platform based on feature pattern to mask and mask design drawing alignment, so that the detection efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of mask defect detection method based on circular detection area. BACKGROUND

[0002] At present, in the process of semiconductor lithography / defect detection, the general mask detection method can only detect square mask, and the detection area can only select square detection area;Such detection mode has the following problems: 1, cannot detect the circular mask;2, for square mask, the distribution of layout on mask is circular, and according to square detection area detection, some areas that do not need to be detected will be detected, resulting in the reduction of production efficiency. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the defects of the prior art, and to provide a mask defect detection method based on circular detection area, which can detect circular mask or square mask circular detection area, and improve the detection efficiency.

[0004] In order to solve the above technical problems, the technical scheme of the present application is as follows: a mask defect detection method based on circular detection area is realized by using a mask defect detection system, the mask defect detection system contains a detection camera and a motion platform loaded with mask, and the steps of the method contain:

[0005] Setting the feature pattern for alignment on the mask design map and selecting the circular detection area by specifying the center (gx0, gy0) and the radius r;

[0006] After loading the mask on the motion platform, the mask on the motion platform and the mask design map are aligned based on the feature pattern by the detection camera, so as to establish the mapping relationship between the motion platform coordinates and the coordinates of the mask design map;

[0007] According to the width pixel number w of the detection camera, the pixel size p of the detection camera, the center coordinates (gx0, gy0) of the circular detection area, the radius r of the circular detection area and the mapping relationship between the motion platform coordinates and the coordinates of the mask design map, the scanning row number row and the starting motion platform coordinates and the terminal motion platform coordinates of each scanning row are calculated;

[0008] Based on the calculated scanning row number row and the starting motion platform coordinates and the terminal motion platform coordinates of each scanning row, the motion platform is triggered to perform serpentine scanning, and the scanning of the entire circular detection area is finally realized by the detection camera;Wherein,

[0009] The calculation method of scanning row number is as follows: row=2*r / (w*p);

[0010] The starting motion platform coordinates and the ending motion platform coordinates of each scanning line are calculated as follows:

[0011] The starting layout coordinates of the i-th scanning line are (gxi_begin, gyi_begin) and the ending layout coordinates are (gxi_end, gyi_end);

[0012] gxi_begin = gx0 - r + w * p * (i - 1);

[0013] gyi_begin = gy0 + pow(-1, i - 1) * sqrt(pow(r, 2) - pow(r - 2 * w * p, 2));

[0014] gxi_end = gx0 - r + w * p * (i - 1);

[0015] gyi_end = gy0 - pow(-1, i - 1) * sqrt(pow(r, 2) - pow(r - 2 * w * p, 2));

[0016] According to the mapping relationship between the motion platform coordinates and the coordinates of the mask design diagram, the starting motion platform coordinates (xi_begin, yi_begin) and the ending motion platform coordinates (xi_end, yi_end) of the corresponding i-th scanning line are calculated.

[0017] i is a natural number from 1 to row.

[0018] Further, the method further has the following steps:

[0019] In the scanning process of the circular detection area, the picture taken by the detection camera is compared with the corresponding picture rendered after segmentation on the mask design diagram to detect defects therein.

[0020] Further, the specific steps of segmenting the corresponding picture on the mask design diagram are as follows:

[0021] According to the starting motion platform coordinates (xi_begin, yi_begin) of the i-th scanning line, the width pixel number w and the height pixel number h of the detection camera, and the pixel size p of the detection camera, the mask design diagram is cut to render a picture of each row and column (i, j); the layout coordinates of the picture corresponding to each row and column (i, j) are: starting coordinates (xi_begin, yi_begin - (j - 1) * h * p) and ending coordinates (xi_begin + w * p, yi_begin - (j - 1) * h * p); wherein the starting coordinates are the coordinates of the top left corner of the picture, and the ending coordinates are the coordinates of the bottom right corner of the picture.

[0022] Further, two feature patterns are set on the mask design graph for alignment, denoted as A and B, wherein A and B are spaced apart and on the same horizontal line;

[0023] The mask and the mask design graph on the motion platform are aligned by the detection camera based on the feature patterns, specifically as follows:

[0024] The corresponding feature patterns on the mask are found, denoted as A' and B';

[0025] A' is moved to the center of the field of view of the detection camera, and the motion platform coordinates (x1, y1) of A' are recorded;

[0026] B' is moved to the center of the field of view of the detection camera, and the motion platform coordinates (x2, y2) of B' are recorded;

[0027] The angle atan((y2-y1) / (x2-x1)) of the mask is calculated, and the mask is rotated horizontally within the motion platform to adjust A' and B' to the same horizontal line;

[0028] After rotation, A' is moved to the center of the field of view, and the coordinates (x, y) of A' are taken as the reference point coordinates;

[0029] According to the coordinates (gx1, gy1) of A on the mask design graph and the reference point coordinates (x, y), the mapping relationship between the motion platform coordinates and the coordinates of the mask design graph is established.

[0030] After the above technical scheme is adopted, the method can not only detect the circular mask, but also detect the square mask with circular distribution of the layout, thereby improving the detection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic diagram of a circular detection area of the present application;

[0032] Figure 2 is a schematic diagram of the motion trajectory of the center detection area of the present application. DETAILED DESCRIPTION

[0033] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments and in conjunction with the drawings.

[0034] As shown in Figure 1 , 2 , a mask defect detection method based on a circular detection area is adopted, which is implemented by a mask defect detection system containing a detection camera and a motion platform loaded with a mask, and the steps of the method contain:

[0035] Setting a feature pattern for alignment on a mask design drawing and selecting a circular detection area by specifying a center (gx0, gy0) and a radius r;

[0036] After loading the mask on the motion platform, the mask on the motion platform and the mask design drawing are aligned by the detection camera based on the feature pattern, so as to establish a mapping relationship between the motion platform coordinates and the coordinates of the mask design drawing;

[0037] According to the width pixel number w of the detection camera, the pixel size p of the detection camera, the center coordinates (gx0, gy0) of the circular detection area, the radius r of the circular detection area, and the mapping relationship between the motion platform coordinates and the coordinates of the mask design drawing, the number of scanning rows row and the starting and ending motion platform coordinates of each scanning row are calculated;

[0038] Based on the calculated number of scanning rows row and the starting and ending motion platform coordinates of each scanning row, the motion platform is triggered to perform a serpentine scan, and the detection camera finally realizes scanning of the entire circular detection area; wherein,

[0039] The calculation method of the number of scanning rows is as follows: row = 2*r / (w*p);

[0040] The calculation method of the starting and ending motion platform coordinates of each scanning row is as follows:

[0041] The starting and ending layout coordinates of the i-th scanning row are (gxi_begin, gyi_begin) and (gxi_end, gyi_end);

[0042] gxi_begin = gx0 - r + w*p*(i-1);

[0043] gyi_begin = gy0 + pow(-1, i-1)*sqrt(pow(r, 2) - pow(r-2*w*p, 2));

[0044] gxi_end = gx0 - r + w*p*(i-1);

[0045] gyi_end = gy0 - pow(-1, i-1)*sqrt(pow(r, 2) - pow(r-2*w*p, 2));

[0046] According to the established mapping relationship between the motion platform coordinates and the coordinates of the mask design drawing, the corresponding starting and ending motion platform coordinates (xi_begin, yi_begin) and (xi_end, yi_end) of the i-th scanning row are calculated;

[0047] i is a natural number from 1 to row.

[0048] In the present embodiment, the mask defect detection system is a prior art, which can be specifically referred to the mask defect detection system disclosed in a method for mask defect detection based on BINNING mode disclosed in a Chinese patent with the application publication number CN 118090734A, and the present embodiment will not be described in detail.

[0049] Specifically, the method further has the following steps in the steps:

[0050] In the scanning process of the circular detection area, the picture taken by the detection camera is compared with the corresponding picture rendered after segmentation on the mask design diagram to detect defects therein.

[0051] Specifically, the specific steps of segmenting the corresponding picture on the mask design diagram are as follows:

[0052] According to the starting motion platform coordinates (xi_begin, yi_begin) of the i-th scanning row, the number of width pixels w and the number of height pixels h of the detection camera, and the pixel size p of the detection camera, the mask design diagram is cut to render a picture of each row and column (i, j); the layout coordinates of the picture corresponding to each row and column (i, j) are: the starting coordinates: (xi_begin, yi_begin-(j-1)*h*p), and the ending coordinates: (xi_begin+w*p, yi_begin-(j-1)*h*p); wherein the starting coordinates are the coordinates of the top left corner of the picture, and the ending coordinates are the coordinates of the bottom right corner of the picture.

[0053] Specifically, two feature patterns are set on the mask design diagram for alignment, denoted as A and B, wherein A and B are spaced apart and on the same horizontal line.

[0054] The alignment of the mask on the motion platform and the mask design diagram by the detection camera based on the feature patterns is specifically:

[0055] Find the corresponding feature patterns on the mask, denoted as A' and B';

[0056] Move A' to the center of the field of view of the detection camera, and record the motion platform coordinates (x1, y1) of A';

[0057] Move B' to the center of the field of view of the detection camera, and record the motion platform coordinates (x2, y2) of B';

[0058] Calculate the angle atan((y2-y1) / (x2-x1)) of the mask plate, and rotate the mask horizontally through the action of the motion platform to adjust A' and B' to the same horizontal line.

[0059] After rotating, A' is moved to the center of the field of view, and the coordinates (x, y) of A' are taken as the reference point coordinates;

[0060] According to the coordinates (gx1, gy1) of A on the mask design graph and the reference point coordinates (x, y), a mapping relationship between the motion platform coordinates and the coordinates of the mask design graph is established.

[0061] By using this method, not only the detection of the circular mask can be realized, but also the square mask with circular distribution of the layout can be detected, and the detection efficiency is improved.

[0062] The above-described specific embodiments further illustrate the technical problems solved by the present application, technical solutions and beneficial effects. It should be understood that the above-described specific embodiments are merely specific embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting defects on a mask based on a circular detection area, implemented by a mask defect detection system, the mask defect detection system comprising a detection camera and a moving platform for loading a mask, characterized in that The steps of the method comprise: Setting a feature pattern for alignment on a mask design map and selecting a circular detection area by specifying a center (gx0, gy0) and a radius r; After loading the mask on the motion platform, the mask on the motion platform and the mask design map are aligned by a detection camera based on the feature pattern, so as to establish a mapping relationship between the motion platform coordinates and the coordinates of the mask design map; The number of scanning rows row and the starting and ending motion platform coordinates of each scanning row are calculated according to the width pixel number w of the detection camera, the pixel size p of the detection camera, the center coordinates (gx0, gy0) of the circular detection area, the radius r of the circular detection area, and the mapping relationship between the motion platform coordinates and the coordinates of the mask design map; Based on the calculated number of scanning rows row and the starting and ending motion platform coordinates of each scanning row, the motion platform is triggered to perform a snake-shaped scan, and the detection camera finally realizes scanning of the entire circular detection area; wherein, The calculation method of the number of scanning rows is as follows: row = 2*r / (w*p); The calculation method of the starting and ending motion platform coordinates of each scanning row is as follows: The starting and ending map coordinates of the i-th scanning row are (gxi_begin, gyi_begin) and (gxi_end, gyi_end); gxi_begin = gx0-r+w*p*(i-1); gyi_begin = gy0+pow(-1,i-1)*sqrt(pow(r,2)-pow(r-2*w*p,2)); gxi_end = gx0-r+w*p*(i-1); gyi_end = gy0-pow(-1,i-1)*sqrt(pow(r,2)-pow(r-2*w*p,2)); According to the established mapping relationship between the motion platform coordinates and the coordinates of the mask design map, the starting and ending motion platform coordinates (xi_begin, yi_begin) and (xi_end, yi_end) of the corresponding i-th scanning row are calculated; i is a natural number from 1 to row.

2. The method of claim 1, wherein, The steps of the method further comprise: During the scanning process of the circular detection area, the picture taken by the detection camera is compared with the corresponding picture rendered after segmentation on the mask design map to detect defects therein.

3. The method of claim 2, wherein: The specific steps of segmenting the corresponding picture on the mask design map are as follows: Cutting the mask design according to the starting motion platform coordinates (xi_begin, yi_begin) of the ith scanning line, the number of width pixels w and the number of height pixels h of the detection camera, and the pixel size p of the detection camera, and rendering a picture of each row and column (i, j); the layout coordinates of the picture corresponding to each row and column (i, j) are: starting coordinates: (xi_begin, yi_begin-(j-1)*h*p), and ending coordinates: (xi_begin+w*p, yi_begin-(j-1)*h*p); wherein the starting coordinates are the coordinates of the top-left corner of the picture, and the ending coordinates are the coordinates of the bottom-right corner of the picture.

4. The method of claim 1, wherein, Two feature patterns are set on the mask design for alignment, denoted as A and B, wherein A and B are spaced apart and on the same horizontal line; The mask and the mask design on the motion platform are aligned based on the feature patterns by using the detection camera, specifically as follows: Find the corresponding feature patterns on the mask, denoted as A' and B'; Move A' to the center of the field of view of the detection camera, and record the motion platform coordinates (x1, y1) of A'; Move B' to the center of the field of view of the detection camera, and record the motion platform coordinates (x2, y2) of B'; Calculate the angle of the mask on the board atan((y2-y1) / (x2-x1)), and rotate the mask horizontally on the motion platform to adjust A' and B' to the same horizontal line; After rotation, move A' to the center of the field of view, and the coordinates (x, y) of A' are taken as the reference point coordinates; According to the coordinates (gx1, gy1) of A on the mask design and the reference point coordinates (x, y), a mapping relationship between the motion platform coordinates and the coordinates of the mask design is established.

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