Mask strip offset compensation method

Abstract

The invention discloses a mask strip offset compensation method, which comprises the following steps: S01, before scanning a current strip and stepping to a next strip, sequentially and circularly querying the previous scanned strip, stopping circulation until the queried strip has offset, and returning an X-direction offset value LX and a Y-direction offset value LY of the offset strip; s02, obtaining an X value X1 and a Y value Y1 of a strip overlapping area between the current strip and the next strip, comparing X1 and LX according to a formula (1) and comparing Y1 and LY according to a formula (2), calculating absolute values of difference values, and calculating an X offset reference value LX1 and a Y offset reference value LY1; and S03, when LX1 is larger than the set X-direction offset threshold value, the X-direction offset distance X is calculated according to a formula (3). The pattern deviation caused by downward deformation of the mask under the influence of gravity is improved, the pattern deviation is ensured to be within an adjustable range, and the occurrence of pseudo defects is reduced to a great extent.

Description

Technical Field

[0001] The invention relates to a method for compensating mask stripe offset, belonging to the technical field of semiconductor defect detection. Background Art

[0002] At present, mask defect detection is performed using a mask defect detection system. The mask defect detection system contains a camera and a motion platform. The mask is loaded on the motion platform. The motion platform is used to move the mask in a serpentine manner, and the mask is scanned by the camera, thereby realizing serpentine scanning of the mask. The mask defect detection system can be specifically referred to in a mask defect detection method based on a BINNING mode disclosed in a Chinese patent application publication number CN118090734A. The system; during mask defect detection, the mask is affected by gravity, and the middle position will deform downward. The larger the size of the mask, the more serious the deformation, resulting in a greater pattern offset as the detection is made further back. In the case of pattern offset, the following problems will arise in mask detection:

[0003] 1. The further back the detection is, the more serious the graphic position shift is, resulting in a large deviation between the actual shot and the filled design layout.

[0004] 2. Many false defects will be generated during detection. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for compensating mask strip offset, which improves the graphic offset caused by the downward deformation of the mask due to the influence of gravity, ensures that the graphic deviation is within an adjustable range, and greatly reduces the occurrence of pseudo defects.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a method for compensating for mask strip offset, the mask defect detection adopts a mask defect detection system, the mask defect detection system comprises a camera and a motion platform, the mask is loaded on the motion platform, the motion platform is used to perform serpentine movement on the mask, and the mask is scanned by the camera, so as to realize serpentine scanning of the mask, and each vertical scanning pattern in the serpentine scanning process is a strip, and the steps of the method include:

[0007] S01: After scanning the current strip and before stepping to the next strip, the previously scanned strips are cyclically queried in sequence until the queried strip has an offset, and the loop is stopped, and the X-direction offset value L of the offset strip is returned. X and Y offset value L Y ;

[0008] S02: Get the X value X of the overlapping area between the current strip and the next strip. 1and Y value Y 1 , respectively according to formula (1) for X 1 and L X And according to formula (2) 1 and L Y Make a comparison, calculate the absolute value of the difference, and calculate the X offset reference value L X1 and Y offset reference value L Y1 ;

[0009] S03: When L X1 > The set X-direction offset threshold, then the X-direction offset distance X is calculated according to formula (3) 距 ; When L Y1 > The Y-direction offset threshold is set, then the Y-direction offset distance Y is calculated according to formula (4): 距 ;

[0010] S04: According to X 距 and Y 距 According to formula (5) and formula (6), the X-direction step value X of the motion platform is 步 and Y direction step value Y 步 Make compensation adjustments, and the next strip will follow X 步 and Y 步 Move to the corresponding position for scanning;

[0011] Formula (1) is L X1 =Math.Abs(X 1 -L X );

[0012] Formula (2) is L Y1 =Math.Abs(Y 1 -L Y );

[0013] Formula (3) is X 距 =L X1 *P 1 ;

[0014] Formula (4) is Y 距 =L Y1 *P 2 ;

[0015] Formula (5) is X 步 =X 原步 -X 距 ;

[0016] Formula (6) is Y 步 =Y 原步 -Y 距 ; Among them, P 1 is the pixel width in the X direction of the camera, P 2is the pixel width of the camera in the Y direction, in um / pixel; L X , L Y , X 1 , Y 1 , L X1 and L Y1 The unit is pixel, X 距 , Y 距 , X 原步 , X 步 , Y 原步 and Y 步 The unit is um.

[0017] Further, in step S01, the previously scanned strips are queried in turn in a loop until all strips are queried and there is no offset in the strips, then the process directly jumps to step S04 and sets X 距 and Y 距 All are 0, the next band is X 原步 and Y 原步 Move to the corresponding position to scan.

[0018] Further, in step S03, when L X1 ≤ the set X-direction offset threshold, then set X 距 is 0; when L Y1 ≤ the set Y offset threshold, then set Y 距 is 0.

[0019] After adopting the above technical solution, the method of the present invention improves the pattern deviation caused by the downward deformation of the mask due to the influence of gravity, ensures that the pattern deviation is within an adjustable range, and greatly reduces the occurrence of pseudo defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the serpentine scanning of the mask of the present invention. DETAILED DESCRIPTION

[0021] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments in conjunction with the accompanying drawings.

[0022] A method for compensating for mask strip offset, wherein the mask defect detection adopts a mask defect detection system, the mask defect detection system comprises a camera and a motion platform, the mask is loaded on the motion platform, the motion platform is used to perform serpentine movement on the mask, and the mask is scanned by the camera, thereby realizing serpentine scanning of the mask. For details, please refer to Figure 1, scanning from top to bottom or from bottom to top, stepping horizontally, wherein A is a strip, and each vertical scanning pattern in the serpentine scanning process is a strip. The mask defect detection system can specifically refer to the mask defect detection system disclosed in a method for mask defect detection based on a BINNING mode disclosed in a Chinese patent application publication number CN118090734A. This embodiment will not be described in detail. The steps of the method include:

[0023] S01: After scanning the current strip and before stepping to the next strip, the previously scanned strips are cyclically queried in sequence until the queried strip has an offset, and the loop is stopped, and the X-direction offset value L of the offset strip is returned. X and Y offset value L Y ; The strip with offset here is the strip that is closest to the next strip to be scanned and has offset;

[0024] S02: Get the X value X of the overlapping area between the current strip and the next strip. 1 and Y value Y 1 , respectively according to formula (1) for X 1 and L X And according to formula (2) 1 and L Y Make a comparison, calculate the absolute value of the difference, and calculate the X offset reference value L X1 and Y offset reference value L Y1 ; The overlapping area of ​​the strips here is to prevent missing shots. When the camera takes pictures, it will take more pictures that have been taken, that is, the motion platform steps by a value smaller than the step value of the next strip, and the camera scans the pictures;

[0025] S03: When L X1 > The set X-direction offset threshold, then the X-direction offset distance X is calculated according to formula (3) 距 ; When L Y1 > The Y-direction offset threshold is set, then the Y-direction offset distance Y is calculated according to formula (4): 距 ;

[0026] S04: According to X 距 and Y 距 According to formula (5) and formula (6), the X-direction step value X of the motion platform is 步 and Y direction step value Y 步 Make compensation adjustments, and the next strip will follow X 步 and Y 步 Move to the corresponding position for scanning;

[0027] Formula (1) is L X1 =Math.Abs(X 1 -L X );

[0028] Formula (2) is L Y1 =Math.Abs(Y 1 -L Y );

[0029] Formula (3) is X 距 =L X1 *P 1 ;

[0030] Formula (4) is Y 距 =L Y1 *P 2 ;

[0031] Formula (5) is X 步 =X 原步 -X 距 ;

[0032] Formula (6) is Y 步 =Y 原步 -Y 距 ; Among them, P 1 is the pixel width in the X direction of the camera, P 2 is the pixel width of the camera in the Y direction, in um / pixel; L X , L Y , X 1 , Y 1 , L X1 and L Y1 The unit is pixel, X 距 , Y 距 , X 原步 , X 步 , Y 原步 and Y 步 The unit is um.

[0033] In this embodiment, P 1 The value of can be = P 2 The value of .

[0034] Specifically, in step S01, the previously scanned strips are queried in sequence until all strips are queried and there is no offset in the strips, then the process directly jumps to step S04 and sets X 距 and Y 距 All are 0, the next band is X 原步 and Y 原步 Move to the corresponding position to scan.

[0035] Specifically, in step S03, when L X1 ≤ the set X-direction offset threshold, then set X 距 is 0; when L Y1 ≤ the set Y offset threshold, then set Y距 is 0.

[0036] After stepping dynamic adjustment, the image captured by the camera is closer to the mask design layout, thereby improving the matching degree between the two, so that smaller defects can be detected and the number of false defects is effectively reduced, thus improving the detection accuracy of the detection equipment.

[0037] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for compensating for mask strip offset, wherein a mask defect detection system is used for mask defect detection, and the mask defect detection system comprises a camera and a motion platform, the mask is loaded on the motion platform, the motion platform is used to perform serpentine movement on the mask, and the mask is scanned by the camera, thereby realizing serpentine scanning of the mask, and each vertical scanning pattern in the serpentine scanning process is a strip, characterized in that: The steps of the method include: S01: After scanning the current strip and before stepping to the next strip, the previously scanned strips are cyclically queried in sequence until the queried strip has an offset, and the loop is stopped, and the X-direction offset value L of the offset strip is returned. X and Y offset value L Y ; S02: Obtain the X value X1 and Y value Y1 of the overlapping area between the current strip and the next strip, and calculate X1 and L according to formula (1) respectively. X And according to formula (2), Y1 and L Y Make a comparison, calculate the absolute value of the difference, and calculate the X offset reference value L X1 and Y offset reference value L Y1 ; S03: When L X1 > The set X-direction offset threshold, then the X-direction offset distance X is calculated according to formula (3) 距 ; When L Y1 > The Y-direction offset threshold is set, then the Y-direction offset distance Y is calculated according to formula (4): 距 ; S04: According to X 距 and Y 距 According to formula (5) and formula (6), the X-direction step value X of the motion platform is 步 and Y direction step value Y 步 Make compensation adjustments, and the next strip will follow X 步 and Y 步 Move to the corresponding position for scanning; Formula (1) is L X1 =Math.Abs(X1-L X ); Formula (2) is L Y1 =Math.Abs(Y1-L Y ); Formula (3) is X 距 =L X1 *P1; Formula (4) is Y 距 =L Y1 *P2; Formula (5) is X 步 =X 原步 -X 距 ; Formula (6) is Y 步 =Y 原步 -Y 距 ; Where P1 is the pixel width in the X direction of the camera, P2 is the pixel width in the Y direction of the camera, and the unit is um / pixel; L X , L Y , X1, Y1, L X1 and L Y1 The unit is pixel, X 距 , Y 距 , X 原步 , X 步 , Y 原步 and Y 步 The unit is um.

2. The method according to claim 1, characterized in that In step S01, the previously scanned strips are queried in turn until all strips are queried and there is no offset in the strips, then the process directly jumps to step S04 and sets X 距 and Y 距 All are 0, the next band is X 原步 and Y 原步 Move to the corresponding position to scan.

3. The method according to claim 1, characterized in that In step S03, When L X1 ≤ the set X-direction offset threshold, then set X 距 is 0; when L Y1 ≤ the set Y offset threshold, then set Y 距 is 0.

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