Mask inspection machine precision calibration sample

Abstract

The application discloses a mask inspection machine precision calibration sample, which comprises a substrate, a position calibration area and a precision calibration area are arranged on the substrate; a contrast pattern unit and a defect pattern unit are arranged in the precision calibration area; a plurality of mask sample contrast patterns are arranged in a horizontal and vertical array in the contrast pattern unit, the mask sample contrast patterns in the same row in the contrast pattern unit are consistent, and only the size is increased or decreased; a plurality of mask sample defect patterns are arranged in a horizontal and vertical array in the defect pattern unit, the mask sample defect patterns in the same row in the defect pattern unit are consistent, and only the size is increased or decreased; the mask sample contrast patterns and the mask sample defect patterns in the same row and column position in the contrast pattern unit and the defect pattern unit are consistent, and the sizes are the same, and only a defect feature is additionally arranged in the mask sample defect pattern; the mask inspection machine precision calibration sample solves the problem of full inspection of calibration and defects of the mask inspection machine precision.

Description

Technical Field

[0001] This invention belongs to the field of photomask processing equipment, and more specifically relates to a photomask inspection machine for calibrating a sample. Background Technology

[0002] In the production process of our G8.5 generation photomasks, we use the world's mainstream 0.35μm sensitivity automated optical inspection (AOI) machine for defect control.

[0003] These mask inspection machines are equipped with two different magnifications (high magnification and low magnification). The minimum inspection accuracy with high magnification is 0.35μm, and with low magnification it is 0.75μm. Due to the complexity of product models and patterns in the mask industry, the inspection capabilities of automated optical inspection (AOI) machines pose a significant challenge. Currently, our company's automated optical inspection systems are divided into Die-to-Die and Die-to-DB inspection methods. Die-to-Die can be understood as comparing two identical parts of a pattern, with the machine calculating defects. Die-to-DB can be understood as performing a data difference analysis between the actual product and the design GDS data, ultimately calculating and outputting defects.

[0004] Considering the complexity and diversity of product defects, and to ensure the inspection capabilities of automated optical inspection machines (AOIs), it is particularly important to design and develop a dedicated calibration sample for the inspection machine. This sample design can, on the one hand, satisfy the user's control over the machine's precision and allow for the correction of sensitivity files according to customer specifications. On the other hand, it can effectively prevent customer malfunctions caused by AOIs missing defects, thereby improving the production yield and ensuring quality. Summary of the Invention

[0005] The purpose of this invention is to provide a precision calibration sample for a mask inspection machine, which solves the problem of satisfying the calibration of the precision of the mask inspection machine and the full inspection of defects as proposed in the background art.

[0006] The present invention provides a precision calibration sample for a mask inspection machine, comprising a substrate, wherein a position calibration area and a precision calibration area are provided on the substrate;

[0007] The precision calibration area is provided with a comparison graphic unit and a defect graphic unit, and the comparison graphic unit area and the defect graphic unit area are arranged in an axisymmetric manner about the central axis of the precision calibration area.

[0008] The comparison graphic unit contains several mask sample comparison graphics arranged horizontally and vertically. The mask sample comparison graphics in the same row of the comparison graphic unit are identical, with only the size increasing or decreasing; the mask sample comparison graphics in the same column of the comparison graphic unit are different, but the size is the same.

[0009] The defect pattern unit contains several mask sample defect patterns arranged horizontally and vertically. The defect patterns of each mask sample in the same row of the defect pattern unit are the same, with only the size increasing or decreasing. The defect patterns of each mask sample in the same column of the defect pattern unit are different, but the size is the same.

[0010] The mask sample comparison pattern and the mask sample defect pattern in the same row and column position of the comparison pattern unit and the defect pattern unit are consistent, except that defect features are added to the mask sample defect pattern, but the size is the same.

[0011] Preferably, the comparison patterns of each mask sample in the same row within the comparison pattern unit are consistent, with only the size increasing sequentially; the defect patterns of each mask sample in the same row within the defect pattern unit are consistent, with only the size increasing sequentially.

[0012] Preferably, the sizes of the mask sample comparison patterns in the same row within the comparison pattern unit are sequentially 0.1μm, 0.2μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.75μm, 1.0μm, 1.5μm, 1.75μm, 2.0μm, 3.0μm, 4.0μm, and 5.0μm; the mask samples in the same row within the defect pattern unit... The defect pattern sizes of the sample templates are 0.1μm, 0.2μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.75μm, 1.0μm, 1.5μm, 1.75μm, 2.0μm, 3.0μm, 4.0μm, and 5.0μm, respectively; the center distance between the comparison patterns of two adjacent mask templates in the same row within the comparison pattern unit is 20μm.

[0013] Preferably, the defect graphic unit has 26 rows, each row including a defect type, the defect type including line edge defects, corner defects, pinhole defects and point defects at different angles; the line edge defects at different angles include line edge defects at 0°, 45°, 90° and 135°.

[0014] Preferably, the comparison graphic unit and the defect graphic unit are arranged in a left-right position, and the size of the mask sample comparison graphic and the mask sample defect graphic both increase sequentially from left to right.

[0015] Preferably, two horizontal alignment lines are provided in the position calibration area. The two horizontal alignment lines are arranged symmetrically about the central axis of the precision calibration area and are respectively located at the bottom of the comparison pattern unit and the defect pattern unit. The length of the horizontal alignment line is 10 mm and the width is 2 mm. The horizontal alignment lines are obtained by sputtering pure chromium on the substrate.

[0016] Preferably, the position calibration area is further provided with four cross-shaped limit marks. The four cross-shaped limit marks are respectively located outside the four vertices of the comparison graphic unit and the defect graphic unit. The distance between the cross-shaped limit marks and the edge of the substrate is 20mm. The outer contour size of the cross-shaped limit marks is 200*200um. The single line width of the cross-shaped limit marks is 20um. Except for the four cross-shaped limit marks and the two horizontal alignment lines, the rest of the position calibration area is a supplementary lighting blank area.

[0017] Preferably, the substrate is a glass substrate, and a dustproof film is coated on the glass substrate. The dustproof film covers the outside of the comparison pattern unit, the defect pattern unit, the horizontal alignment line and the four "+" limit marks.

[0018] The beneficial effects of the mask inspection machine precision calibration sample of the present invention are as follows:

[0019] 1. It can quickly calibrate the accuracy and defect inspection of the mask inspection machine, and the calibration time can generally be controlled within 10 minutes, which is highly efficient.

[0020] 2. The defects covered are comprehensive and highly targeted at defects encountered in production.

[0021] 3. The design of the comparison graphic unit and the defect graphic unit is reasonable, and it can simultaneously verify the Die To Die and Die To DB inspection logic of the equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a sample for calibrating the precision of a mask inspection machine, which is a technical solution of the present invention.

[0023] Figure 2 This invention relates to a schematic diagram showing the arrangement of a mask plate sample comparison image and a mask plate sample defect image on a mask plate inspection machine precision calibration sample.

[0024] Figure 3 This is a schematic diagram illustrating the types of defect patterns on a mask sample for a mask inspection machine precision calibration sample, which is part of the technical solution of this invention. Detailed Implementation

[0025] To facilitate understanding of the technical solution of the present invention by those skilled in the art, the technical solution of the present invention will now be further described in conjunction with specific embodiments and the accompanying drawings.

[0026] The present invention provides a precision calibration sample for a mask inspection machine, comprising a substrate 1, on which a position calibration area 2 and a precision calibration area 3 are provided. When the substrate 1 is mounted onto the mask inspection machine, the position calibration area 2 is used to align the mounting position of the substrate 1, ensuring that all patterns within the precision calibration area 3 are within the inspection field of view of the inspection machine. In other words, the position calibration area 2 enables rapid alignment of the substrate 1 during mounting.

[0027] In this invention, a comparison pattern unit 31 and a defect pattern unit 32 are provided within the precision calibration area 3. The areas of the comparison pattern unit 31 and the defect pattern unit 32 are arranged axially symmetrically about the central axis of the precision calibration area. Here, axial symmetry refers to the entire area of ​​the comparison pattern unit 31 and the defect pattern unit 32, not just the mask sample comparison pattern and the mask sample defect pattern within the comparison pattern unit 31 and the defect pattern unit 32 being symmetrically arranged about the central axis of the precision calibration area. This arrangement ensures that the precision calibration sample of this mask inspection machine meets the inspection requirements of the mask inspection machine in Die To Die mode.

[0028] In the technical solution of this invention, several mask sample comparison patterns P10 are arranged horizontally and vertically within the comparison pattern unit 31. The mask sample comparison patterns P10 in the same row within the comparison pattern unit 31 are identical, differing only in size. That is, as... Figure 1 In the comparison graphic unit 31, within row V1, the comparison graphics P10 of each mask sample are identical, differing only in size; for example... Figure 2 All graphics in the same row as graphic A1 are identical to graphic A1, such as graphic A16, which is identical to graphic A1. Comparison graphics P10 in the same column within graphic unit 31 differ in appearance but have the same size. That is, as shown... Figure 1 In the comparison graphic unit 31, within column Ma, the comparison graphics P10 of each mask sample are the same size, but each graphic is different; for example... Figure 2 In the column containing graphic A1, all graphics are the same size as graphic A1, but the graphics are different. That is, graphic A1 and graphic C1 are the same size but different graphics, and graphic A16 and graphic C16 are the same size but different graphics.

[0029] In the technical solution of this invention, a plurality of mask sample defect patterns P20 are arranged horizontally and vertically within the defect pattern unit 32. The mask sample defect patterns P20 in the same row within the defect pattern unit 32 are identical, differing only in size. That is, as... Figure 1In the middle, within the defect pattern unit 32, in row W1, the defect patterns P20 of each mask sample are the same, only the size is different; Figure 2 In the table, all graphics within the same row as graphic B1 are identical to graphic B1, but differ in size; that is, graphic B1 and graphic B16 are identical in shape but different in size. Within defect graphic unit 32, the defect graphics P20 of each mask sample are different, but have the same size. That is, as shown... Figure 1 In the defect pattern unit 32, within column La, the defect patterns P20 of each mask sample are the same size, but the patterns of the defect patterns P20 of each mask sample are different; for example... Figure 2 In the column containing graphic B1, all the graphics have the same dimensions as graphic B1, but the graphics themselves are different. That is, graphic B1 and graphic D1 have different graphics but the same dimensions, and graphic B16 and graphic D16 have different graphics but the same dimensions.

[0030] In the technical solution of this invention, the mask sample comparison pattern and the mask sample defect pattern at the same row and column position in the comparison pattern unit 31 and the defect pattern unit 32 are consistent, except that defect features are added to the mask sample defect pattern, but the size is the same. That is, as Figure 1 In the comparison graphic unit 31, row V1, the graphic is consistent with the graphic in the defect graphic unit 32, row W1. More specifically, column Ma in row V1 of comparison graphic unit 31 is consistent with column La in row W1 of defect graphic unit 32. However, the mask sample defect graphic P20 in column La of row W1 of defect graphic unit 32, compared to the mask sample comparison graphic P10 in column Ma of row V1 of comparison graphic unit 31, only has added defect features; otherwise, there is no difference. That is... Figure 2 In the diagram, the graphics in the row containing graphic B1 are identical to those in the row containing graphic A1, but graphic B1 adds defect features to each graphic compared to those in graphic A1. For example... Figure 2 As shown, the small white areas existing within the black areas in Figures B1 to D16 are the aforementioned defect features.

[0031] The term "consistency" here refers to the consistency of information contained in the graphics. Each graphic is formed on substrate 1 through processes such as exposure, development, etching, and stripping, and each graphic is an independent, mature mask. Comparing the graphic information in each row of graphic unit 31 and defect graphic unit 32, which are consistent, although the graphic dimensions within each row vary, the term "consistency" is used. "Consistency" means that a thing or item is arranged according to a certain predictable pattern. Things or items that maintain "consistency" have similar or identical characteristics, or characteristics that change according to a predictable pattern. Therefore, in the description of the above scheme, "graphic consistency" means that the graphics are identical in all aspects except for differences in size or defect characteristics. The description of the above scheme also uses the term "identical," which means completely identical, with no different characteristics appearing, such as "identical size."

[0032] Based on the above technical solution, when the inspection machine uses the mask inspection machine precision calibration sample for calibration, it uses Die To Die for precision calibration and Die To DB for defect calibration. The specific calibration operation is as follows: First, obtain the image information of the mask sample comparison image P10 in a certain row and column of the comparison image unit 31; then obtain the image information of the mask sample defect image P20 in the corresponding row and column position within the defect image unit 32; then compare the image information of the mask sample comparison image P10 with the image information of the mask sample defect image P20, where the compared information includes precision and defects. The precision and defects of the mask sample defect image P20 detected by the inspection machine at this time represent the precision and defect detection capability of the inspection machine. To further obtain or determine the precision of the inspection machine, the inspection machine needs to inspect the smaller-sized mask sample comparison image P10 and mask sample defect image P20. If the inspection machine continues to detect the precision of smaller dimensions, then the precision of this image is the precision of the inspection machine. If it is also necessary to judge the defect inspection capability of the inspection machine, the inspection machine needs to inspect the patterns in different rows. If a defect is found in the mask sample defect pattern P20, the inspection machine can detect the defect type corresponding to the mask sample defect pattern P20. By analogy, the inspection machine can sequentially inspect each mask sample defect pattern P20 in the defect pattern unit 32, and finally obtain the highest accuracy and defect inspection and judgment capability of the inspection machine.

[0033] In this invention, to facilitate inspection machine operation and improve inspection and calibration efficiency, the comparison graphics P10 of each mask sample in the same row of the comparison graphics unit 31 are identical, with their sizes increasing sequentially. Similarly, the defect graphics P20 of each mask sample in the same row of the defect graphics unit 32 are identical, with their sizes increasing sequentially. To further simplify the inspection machine operation and improve efficiency, while also satisfying the Die-to-Die inspection method, the comparison graphics unit 31 and the defect graphics unit 32 are positioned left-right, with the sizes of both the mask sample comparison graphics P10 and the mask sample defect graphics P20 increasing sequentially from left to right.

[0034] The size of the mask sample comparison graphics and the mask sample defect graphics in the same row and column position within the comparison graphics unit 31 and the defect graphics unit 32 are consistent. That is, the setting pattern of the mask sample comparison graphics P10 and the mask sample defect graphics P20 in the comparison graphics unit 31 and the defect graphics unit 32 is consistent, facilitating rapid inspection by the inspection machine and meeting the requirements of Die To Die and Die To DB inspection methods. Figure 1 In the comparison pattern unit 31, the mask sample comparison pattern P10 in column V1, section Ma is identical to the mask sample defect pattern P20 in column W1, section La of the defect pattern unit 32. However, the defect pattern P20 in column W1, section La of the defect pattern unit 32 has added defect features compared to the mask sample comparison pattern P10 in column V1, section Ma of the comparison pattern unit 31. This is all; otherwise, they remain the same. Similarly, the mask sample comparison pattern P10 in column Vn, section Mb of the comparison pattern unit 31 and the mask sample defect pattern P20 in column Wn, section Lb of the defect pattern unit 32 are identical. However, the defect pattern P20 in column Wn, section Lb of the defect pattern unit 32 has added defect features compared to the mask sample comparison pattern P10 in column Vn, section Mb of the comparison pattern unit 31. This is all; otherwise, they remain the same. In the comparison pattern unit 31, row Vn, the two mask sample comparison patterns P10 of columns Ma and Mb are identical, but their sizes are different; the size of the mask sample comparison pattern P10 of column Mb is larger than the size of the mask sample comparison pattern P10 of column Ma. Similarly, in the defect pattern unit 32, row Wn, the two mask sample defect patterns P20 of columns La and Lb are identical, but their sizes are different; the size of the mask sample defect pattern P20 of column Lb is larger than the size of the mask sample defect pattern P20 of column La.

[0035] In the technical solution of this invention, the sizes of the mask sample comparison patterns P10 in the same row within the comparison pattern unit 31 are 0.1μm, 0.2μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.75μm, 1.0μm, 1.5μm, 1.75μm, 2.0μm, 3.0μm, 4.0μm, and 5.0μm, respectively. Similarly, within the defect pattern unit 32, the dimensions of the mask sample defect patterns P20 in the same row are 0.1μm, 0.2μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.75μm, 1.0μm, 1.5μm, 1.75μm, 2.0μm, 3.0μm, 4.0μm, and 5.0μm, respectively. The center distance between adjacent mask sample comparison patterns in the same row of the comparison pattern unit 31 is 20µm, and the center distance between adjacent mask sample defect patterns in the same row of the defect pattern unit is also 20µm. The step size between adjacent patterns is 20µm, facilitating inspection and calibration using the Die-to-Die method. During inspection, the image corresponding to the inspection machine's precision indicates the machine's precision. For example, if the machine starts by inspecting a 5.0μm image and sequentially inspects images of 4.0μm, 3.0μm...0.35μm, and 0.3μm sizes, but fails to detect defects in the next image of 0.2μm size, then the machine's precision is 0.3μm.

[0036] In the technical solution of this invention, such as Figure 1 As shown, the defect graphic unit 32 has 26 rows, such as... Figure 2 As shown, each row includes a defect type, which includes edge defects, corner defects, pinhole defects, and point defects at different angles; edge defects at different angles include 0°, 45°, 90°, and 135° edge defects. Figure 3 As shown, P1 represents a normal feature where a feature addition defect occurs within P3, and P2 represents a normal feature where a feature loss defect occurs within P4. In region Q1, defects are feature addition or loss defects occurring at the 45° and 135° line edges. In region Q2, defects are feature addition or loss defects occurring at the 0° and 90° line edges. In region Q3, defects are corner defects, meaning feature addition or loss defects occur at the apex or concave corner of the normal feature area. In region Q4, defects are pinhole defects and point defects. Pinhole defects are feature loss defects, and point defects are feature addition defects. The upper image in region Q4 represents point defects, and the lower image represents pinhole defects.

[0037] In this invention, two horizontal alignment lines 21 are provided within the position calibration area 2. These two horizontal alignment lines 21 are axially symmetrical about the central axis of the accuracy calibration area 3, and are respectively located at the bottom of the comparison graphic unit 31 and the defect graphic unit 32. The length (h3) of each horizontal alignment line 21 is 10 mm, and the width (h2) is 2 mm. The horizontal alignment lines 21 are obtained by sputtering pure chromium onto the substrate 1. The two horizontal alignment lines 21 ensure that the substrate 1 is level, i.e., they are used for alignment when the substrate is mounted on the inspection machine. This avoids false detections by the inspection machine due to insufficient substrate levelness, preventing the acquisition of priority data and affecting the accuracy of the inspection machine.

[0038] In this invention, the position calibration area 2 is further provided with four crosshair limit marks 22, which are located outside the four apex corners of the comparison graphic unit 31 and the defect graphic unit 32, respectively. The distance (h6) between the crosshair limit marks and the edge of the substrate is 20mm, ensuring that the graphics on the calibration sample are all within the inspection area of ​​the inspection machine. The outer contour dimension (h4) of the crosshair limit marks is 200*200um, and the single stroke width (h5) of the crosshair limit marks is 20um. Except for the four crosshair limit marks 22 and the two horizontal alignment lines 21, the rest of the position calibration area 2 is a supplementary lighting white space, used for light source compensation when calibrating the inspection machine using the calibration sample. The crosshair limit marks greatly facilitate the adjustment of the inspection machine's focus.

[0039] In this invention, substrate 1 is a glass substrate covered with a dustproof film. The dustproof film covers the outside of the comparison pattern unit, defect pattern unit, horizontal alignment line, and four "+" shaped limit marks. The dustproof film provides protection for this precision calibration sample, ensuring the cleanliness of the inspection and eliminating the time wasted by secondary cleaning before inspection.

[0040] The technical solution of the present invention has been described above by way of example in conjunction with the embodiments and accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A sample for precision calibration of a mask inspection machine, characterized in that, Includes a substrate, on which a position calibration area and a precision calibration area are provided; The precision calibration area is provided with a comparison graphic unit and a defect graphic unit, and the comparison graphic unit area and the defect graphic unit area are arranged in an axisymmetric manner about the central axis of the precision calibration area. The comparison graphic unit contains several mask sample comparison graphics arranged horizontally and vertically. The mask sample comparison graphics in the same row of the comparison graphic unit are identical, with only size variations. The mask sample comparison graphics in the same column of the comparison graphic unit are different, but have the same size. The mask sample comparison graphics are composed of at least horizontal and vertical lines, or incorporate 45° / 135° diagonal lines to form more complex graphics. The defect pattern unit contains several mask sample defect patterns arranged horizontally and vertically. Within the same row of the defect pattern unit, the mask sample defect patterns are identical, differing only in size. Within the same column of the defect pattern unit, the mask sample defect patterns are different, but the sizes are the same. Each row of the defect pattern unit includes a defect type, which includes line edge defects, corner defects, pinhole defects, and point defects at different angles. The line edge defects at different angles include line edge defects at 0°, 45°, 90°, and 135°. The mask sample comparison pattern and the mask sample defect pattern in the same row and column position of the comparison pattern unit and the defect pattern unit are consistent, except that defect features are added to the mask sample defect pattern, but the size is the same.

2. The precision calibration sample for the mask inspection machine according to claim 1, characterized in that, Within the comparison graphic unit, the comparison graphics of each mask sample in the same row are consistent, with only the size increasing sequentially; within the defect graphic unit, the defect graphics of each mask sample in the same row are consistent, with only the size increasing sequentially.

3. The mask plate inspection machine precision calibration sample according to claim 2, characterized in that, The mask sample comparison patterns in the same row within the comparison pattern unit have the following sizes, sequentially: 0.1μm, 0.2μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.75μm, 1.0μm, 1.5μm, 1.75μm, 2.0μm, 3.0μm, 4.0μm, and 5.0μm; the mask samples in the same row within the defect pattern unit... The defect pattern sizes are 0.1μm, 0.2μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.75μm, 1.0μm, 1.5μm, 1.75μm, 2.0μm, 3.0μm, 4.0μm, and 5.0μm, respectively; the center distance between the comparison patterns of two adjacent mask samples in the same row within the comparison pattern unit is 20μm.

4. The mask plate inspection machine precision calibration sample according to claim 2, characterized in that, The defect graphic unit contains 26 rows.

5. The mask plate inspection machine precision calibration sample according to claim 1, characterized in that, The comparison graphic unit and the defect graphic unit are arranged in a left-right position, and the size of the mask sample comparison graphic and the mask sample defect graphic both increase sequentially from left to right.

6. The precision calibration sample for the mask inspection machine according to claim 1, characterized in that, Two horizontal alignment lines are provided in the position calibration area. The two horizontal alignment lines are arranged symmetrically about the central axis of the accuracy calibration area and are respectively located at the bottom of the comparison graphic unit and the defect graphic unit. The length of the horizontal alignment line is 10 mm and the width is 2 mm. The horizontal alignment lines are obtained by sputtering pure chromium onto a substrate.

7. The mask plate inspection machine precision calibration sample according to claim 6, characterized in that, The position calibration area is also provided with four cross-shaped limit marks. The four cross-shaped limit marks are located outside the four vertices of the comparison graphic unit and the defect graphic unit, respectively. The distance between the cross-shaped limit marks and the edge of the substrate is 20mm. The outer contour size of the cross-shaped limit marks is 200*200um. The single line width of the cross-shaped limit marks is 20um. Except for the four cross-shaped limit marks and the two horizontal alignment lines, the rest of the position calibration area is a fill light blank area.

8. The precision calibration sample for the mask inspection machine according to claim 1, characterized in that, The substrate is a glass substrate, and a dustproof film is coated on the glass substrate. The dustproof film covers the outside of the comparison pattern unit, the defect pattern unit, the horizontal alignment line and the forty-cross limit mark.

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