Small-size mask splicing method

Abstract

The invention belongs to a small-size mask splicing method in the technical field of display panels. When the blank distance A is greater than or equal to 2X + Y, adopting a splicing step of a conventional method: directly setting a splicing overlapping region F in the region A; when the blank distance A is smaller than 2X + Y, the splicing step of a shielding method is adopted, specifically, the width F of a splicing overlapping area is set to be larger than or equal to 2X + B, B is equal to the overall width of the glass product pattern, and in other words, the glass product pattern is wrapped in a fourth exposure area; the four-time exposure areas correspond to four corners of the same main exposure area (1), the upper left corner area is taken to maintain the original pattern, and the other upper right corner, the lower left corner and the lower right corner are all provided with shielding blocks. According to the small-size mask splicing method, the final exposure effect of the multiple exposure areas in splicing exposure is equivalent to the normal one-time exposure effect through splicing area design under different conditions, and the phenomena of splicing graph retraction and CD abnormal reduction caused by multiple exposure are avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of display panels, and more particularly, relates to a small-size mask splicing method. Background Art

[0002] With the rapid development of the display panel industry and the actual development of consumer demand, the panel size requirements are getting larger and larger. There is currently a problem that the size of the mask does not match the size of the panel glass that needs to be produced. In order to break through the size limit of the mask and produce larger panels, splicing exposure technology has been widely used in the panel manufacturing industry. Due to the limitations of small-size masks, there are many factors that need to be considered when designing the masks required for the production of different products. In particular, the design of the splicing area is more complicated. For example Figure 6a 、 6b As shown, because the overlapping stitching area involves two or even multiple exposures, this is unavoidable. Otherwise, process variations such as exposure can cause defects such as pattern residue or missing patterns. Therefore, special design is often required for the stitching area. Exposure compensation involves expanding the effective pattern within the multiple exposure area by a certain amount to compensate for the CD loss caused by multiple exposures and process drift. Two or more full exposures within the stitching area will result in overexposure, shrinking the photoresist pattern there. The resulting CD value will be abnormally smaller than that of a normal single-exposure area, and the degree of reduction is positively correlated with the number of exposures. Furthermore, process drift in the stitching area can further exacerbate this shrinkage. In particular, traces within the stitching area may be subject to drift and breakage. Therefore, during mask design, additional CD compensation design is required for the patterns in the stitching area. When designing a mask for stitching exposure, it is generally important to avoid the presence of effective patterns within the double or multiple exposure areas. This can mitigate all process risks associated with multiple exposures. To achieve this goal, appropriately selecting the stitching location and range is crucial in stitching design. However, in actual operations, there are often situations where effective graphics cannot be avoided, and the above-mentioned purpose is difficult to achieve or even impossible to achieve. Or in order to achieve the above-mentioned purpose, other aspects need to be sacrificed, such as changing the tight layout of the panel to the spaced layout. However, this method will not only reduce the utilization rate of the large panel, but also increase the number of subsequent large panel cutting times, thereby increasing production time and cost. On the other hand, the number of exposures in the splicing area directly affects the degree of reduction in the actual process CD value there. Therefore, the CD compensation design required for areas with different exposure times is different. This requires multi-faceted verification of the production process to guide the design of different compensation designs. This will undoubtedly increase the difficulty of design and process and reduce the stability and reliability of the process. Therefore, there is a need for improvement in the existing technology.

[0003] In the prior art, there is a technology named "Mask, Mask-Based Stitching Exposure Method" and the publication (announcement) number is "CN109541883A". This technology provides a mask and a mask-based stitching exposure method. The mask is used for stitching exposure of multiple consecutively arranged unit areas on an array substrate. The mask includes a transparent substrate, on which a main light shielding portion and two side light shielding portions are provided. One side light shielding portion, the main light shielding portion, and the other side light shielding portion are connected in sequence along a first direction. A light-transmitting area is provided in each side light shielding portion. The size of the light-transmitting area in the second direction is larger than the size of the main light shielding portion in the second direction, and a specified angle is formed between the first direction and the second direction. The main light-shielding part and the side light-shielding part of the mask are respectively opposite to the corresponding unit areas. Before the exposure machine performs exposure, the light-shielding plate of the exposure machine is set not to block the light-transmitting area of ​​the side light-shielding part. The sub-area in the unit area opposite the light-transmitting area can be irradiated by the exposure machine, and the photoresist and metal layer in the sub-area can be removed. The wiring of the array substrate is cut off in the sub-area, forming a fracture in the wiring.

[0004] However, this technology does not involve the technical problems and technical solutions of the present application. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a small-size mask splicing method is provided with simple steps. Through the design of splicing areas in different situations, the final exposure effect of multiple exposure areas in the splicing exposure is equivalent to the normal single exposure effect, avoiding the shrinkage of the splicing pattern and the abnormal reduction of CD caused by multiple exposures.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is:

[0007] The present invention provides a small-size mask splicing method, and the splicing steps of the small-size mask splicing method are as follows:

[0008] X = minimum line spacing that meets process requirements; Y = minimum overlap distance of shots that meets process requirements, splicing overlap area width F, blank distance A;

[0009] When the blank distance A≥2X+Y, the conventional splicing steps are adopted: directly set the splicing overlap area F in area A;

[0010] When the blank distance A is less than 2X+Y, the blocking method is used for the splicing steps: the splicing overlap area width F is set to be greater than or equal to 2X+B, where B is the overall width of the glass product pattern. That is, the four exposure areas wrap the glass product pattern. The four exposure areas correspond to the four corners of the same main exposure area. The upper left corner area maintains the original pattern, and the other upper right corners, lower left corners, and lower right corners are all set with blocking blocks.

[0011] When the blank distance A is less than 2X+Y and the stitching overlap area width F is limited to F<2X+B, the step-down exposure compensation method is used for stitching: valid graphics exist in both the overlapping second-exposure area and the fourth-exposure area. Conventional design requires separate second-exposure compensation and fourth-exposure compensation. In the step-down exposure compensation method, the fourth-exposure area is moved so that it is completely blank or completely filled with graphics.

[0012] When the conventional stitching method is used, the double-exposure and quadruple-exposure areas are blank areas with no valid graphics, and no additional compensation design is required.

[0013] When using the masking method for stitching, the masking blocks must cover the original pattern and extend beyond the set distance. The secondary exposure area is supplemented with the corresponding pattern or masking blocks in the overlapping area of ​​the stitching, and the placement pattern is consistent with the primary exposure area.

[0014] When the blocking method is used for the stitching step, the pattern in the multiple exposure area is only effectively exposed once, and the remaining exposure times are all blocked, so that the final exposure effect is equivalent to a full exposure.

[0015] When using the reduced exposure compensation method for stitching, the final exposure effect is independent of the number of exposures for areas with completely blank or completely filled graphics. Therefore, the four-exposure area no longer requires exposure compensation design. All graphics within the two-exposure area will have a two-exposure compensation block added.

[0016] The actual effective exposure area of ​​the small-size mask is smaller than the glass size. In the mask, the area used for exposure is called Shot. To fully expose the entire glass, multiple shot arrays of small-size masks need to be spliced ​​together; the main exposure area is used for exposing the product pattern; the secondary exposure area is used to supplement the integrity of the main exposure shot pattern and identify the alignment mark and test block exposure; there is a splicing overlap area width F between adjacent shots.

[0017] In the splicing mask, the four corners are the four exposure areas.

[0018] The splicing mask includes an X-axis and a Y-axis.

[0019] The technical solution of the present invention is adopted, and the working principle and beneficial effects are as follows:

[0020] The small-size mask splicing method described in this invention offers three specific design solutions for different situations. In actual production, the effective exposure area of ​​the mask is often much smaller than the actual glass size. The area within the mask used for exposure is called a shot. To fully expose an entire sheet of glass, the mask must be spliced ​​together into an array of shot patterns. The core design—the primary exposure shot—is used to expose the product pattern; the secondary exposure shot, also known as the side exposure shot, is used to complete the primary exposure pattern and expose various identification alignment marks, test blocks, and other patterns. A certain overlap width is required between the shots. Based on a unique design concept, this invention utilizes splicing area designs for different situations to ensure that the final exposure effect of multiple exposure areas in the spliced ​​exposure is equivalent to that of a normal single exposure, avoiding the shrinkage of the spliced ​​pattern and abnormal CD reduction caused by multiple exposures. When the splicing area cannot avoid the presence of effective patterns, exposure compensation is necessary, and exposure compensation must be considered separately for different exposure levels. When designing a mask for spliced ​​exposure, it is important to minimize the number of exposures of the effective pattern. In this case, the method proposed in this application achieves an optimal solution, ensuring that the effective pattern only has a second exposure, eliminating multiple exposures of more than two times and requiring only a second exposure compensation design. This allows the process to verify the compensation scheme only for the second exposure area, eliminating the need to verify the compensation scheme for each of the three, four, or other multiple exposure areas. This significantly reduces process requirements, while increasing process stability and reliability and improving production yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following is a brief description of the contents and symbols in the drawings of this specification:

[0022] Figure 1a Schematic diagram of a conventional method for splicing small-size masks according to the present invention;

[0023] Figure 1b Schematic diagram of a conventional method for splicing small-size masks according to the present invention;

[0024] Figure 1c Schematic diagram of a conventional method for splicing small-size masks according to the present invention;

[0025] Figure 2a A schematic diagram of the blocking method of the small-size mask splicing method of the present invention;

[0026] Figure 2b A schematic diagram of the blocking method of the small-size mask splicing method of the present invention;

[0027] Figure 2c A schematic diagram of the blocking method of the small-size mask splicing method of the present invention;

[0028] Figure 3 Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0029] Figure 4a Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0030] Figure 4b Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0031] Figure 4c Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0032] Figure 5a Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0033] Figure 5b Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0034] Figure 5c Schematic diagram of the down-exposure compensation method of the small-size mask splicing method of the present invention;

[0035] Figure 6a A simple schematic diagram designed for spliced ​​exposure;

[0036] Figure 6b Schematic diagram of exposure distribution in splicing exposure design (numbers represent exposure times);

[0037] Figure 7 is a schematic diagram of an example pattern located in the four-exposure area;

[0038] The marks in the accompanying drawings are: 1. Main exposure area (main exposure shot); 2. Secondary exposure area (secondary exposure shot, side exposure area, side exposure shot). DETAILED DESCRIPTION

[0039] The following describes the embodiments with reference to the accompanying drawings to further explain in detail the specific embodiments of the present invention, such as the shapes, structures, mutual positions and connection relationships between the various components involved, the functions and working principles of the various components.

[0040] As attached Figure 1a -Attached Figure 7 As shown, the present invention is a small-size mask splicing method.

[0041] The steps of the small-size mask splicing method are as follows:

[0042] X = minimum line spacing that meets process requirements; Y = minimum overlap distance of shots that meets process requirements, splicing overlap area width F, blank distance A;

[0043] like Figure 1a-Figure 1c As shown, when the blank distance A≥2X+Y, the conventional splicing steps are adopted: directly setting the splicing overlap area F in area A;

[0044] like Figure 2a-2c As shown, when the blank distance A is less than 2X+Y, the splicing steps of the blocking method are adopted: the splicing overlap area width F is set to be greater than or equal to 2X+B, where B is the overall width of the glass product pattern, that is, the four exposure areas wrap the glass product pattern; the four exposure areas correspond to the four corners of the same main exposure area 1, the upper left corner area is taken to maintain the original pattern, and the other upper right corner, lower left corner, and lower right corner are all set with blocking blocks.

[0045] like Figure 3 、 Figure 4a-4c 、 Figure 5a-5c As shown in the figure, when the blank distance A is less than 2X+Y and the width F of the stitching overlap area is limited to F<2X+B, the steps of the reduced exposure compensation method are adopted: there are valid patterns in the overlapping secondary exposure area and the fourth exposure area, and the conventional design requires secondary exposure compensation and fourth exposure compensation respectively; in the reduced exposure compensation method, the fourth exposure area is moved so that the fourth exposure area is completely blank or completely filled with patterns.

[0046] The above steps propose improved technical solutions to address the deficiencies in the existing technology. Specifically, a small-size mask (photomask) splicing design method is disclosed, and three specific design solutions are given for different situations. Because in actual production, there is often a situation where the actual effective exposure area of ​​the mask is much smaller than the actual production glass size. The area used for exposure in the mask is called a shot. In order to completely expose a whole piece of glass, the mask needs to be spliced ​​together into a shot array. Among them, the core design - the main exposure shot is used for exposing the product pattern; the secondary exposure shot is also called the side exposure shot, which is used to supplement the integrity of the main exposure shot pattern and expose various identification alignment marks, test blocks, etc.; there needs to be a certain splicing overlap width between shots. Based on a unique design concept, the present invention makes the final exposure effect of multiple exposure areas in the splicing exposure equivalent to the normal single exposure effect through the design of splicing areas under different circumstances, avoiding the shrinkage of the splicing pattern and the abnormal reduction of CD caused by multiple exposures. In the case where the splicing area cannot avoid the existence of effective patterns, exposure compensation design is inevitable. The exposure degree of the area is different, and exposure compensation also needs to be considered separately. When designing a mask for splicing exposures, it's important to minimize the number of exposures for the effective pattern. In this case, the method in this application achieves the optimal solution, ensuring only a second exposure for the effective pattern, eliminating multiple exposures beyond two and requiring only a second exposure compensation design. This allows the process to verify only the compensation scheme for the twice-exposure area, eliminating the need to verify compensation schemes for triple, quadruple, and other multiple exposure areas. This significantly reduces process requirements, while increasing process stability and reliability and improving production yield.

[0047] When the conventional stitching method is used, the double-exposure and quadruple-exposure areas are blank areas with no valid graphics, and no additional compensation design is required.

[0048] When using the masking method for the stitching step, the masking block is required to cover the original pattern and extend beyond the set distance (the larger the better, based on process capabilities and design limitations). The secondary exposure area 2 is supplemented with the corresponding pattern or masking block in the overlapping area of ​​the stitching, and the placement pattern is consistent with the primary exposure area.

[0049] When the blocking method is used for the stitching step, the pattern in the multiple exposure area is only effectively exposed once, and the remaining exposure times are all blocked, so that the final exposure effect is equivalent to a full exposure.

[0050] When using the reduced exposure compensation method for stitching, the final exposure effect is independent of the number of exposures for areas with completely blank or completely filled graphics. Therefore, the four-exposure area no longer requires exposure compensation design. All graphics within the two-exposure area will have a two-exposure compensation block added.

[0051] The actual effective exposure area of ​​the small-size mask is smaller than the glass size. In the mask, the area used for exposure is called a shot. To fully expose the entire glass, multiple shot arrays of small-size masks need to be spliced ​​together; the main exposure area 1 is used for exposing the product pattern; the secondary exposure area 2, also known as the side exposure area, is used to supplement the integrity of the main exposure shot pattern and identify the alignment mark and test block exposure; there is a splicing overlap area width F between adjacent shots.

[0052] In the splicing mask, the four corners are the four exposure areas. Figure 7 The example pattern in the four-exposure area is shown in FIG. The stitching mask includes an X-axis and a Y-axis.

[0053] Figure 6a A simple schematic diagram designed for stitched exposure. Figure 6b Exposure distribution in the spliced ​​exposure design. The numbers indicate the number of exposures.

[0054] Figures 1a-1c For Scheme I, Figure 1a To divide the overlapping areas for splicing; Figure 1b A brief schematic diagram of the overall splicing exposure design; Figure 1c The main exposure is the Shot, where the frame line is the Shot boundary line.

[0055] Figures 2a-2c For Scheme II, Figure 2a To divide the overlapping areas for splicing; Figure 2b A brief schematic diagram of the overall splicing exposure design; Figure 2c The main exposure shot. The frame line is the shot boundary line.

[0056] Figure 3 For analysis of overlapping areas of stitching.

[0057] Figure 4a-4c For Scheme III, Figure 4a To stitch the divisions of the overlapping areas, the four exposure areas are located in the blank space; Figure 4b This is a brief schematic diagram of the overall splicing exposure design scheme; Figure c is the main exposure shot, where the frame line is the shot boundary line; the color-filled figure is the secondary exposure compensation block.

[0058] Figures 5a-5c For Scheme III, Figure 5a To stitch the overlapping areas, the divisions are located in the blank space, and the four exposure areas are located within the pattern; Figure 5b A brief schematic diagram of the overall splicing exposure design; Figure 5c It is the main exposure Shot, where the frame line is the Shot boundary line; the color-filled graphic is the secondary exposure compensation block.

[0059] The key points and points to be protected of the present invention are: 1. For areas that are completely blank or completely filled with graphics, the final exposure effect has nothing to do with the number of exposures and does not require any exposure compensation design. The conventional method (Scheme I) and the reduced exposure compensation method (Scheme III) of the present invention both take advantage of this point, and set the multiple exposure area in the above-mentioned area from a design perspective, so that its final exposure effect is equivalent to one exposure. 2. The blocking method (Scheme II) only retains one corner area in the multiple exposure areas at the four corners of the main exposure Shot to maintain the original pattern, and sets blocking blocks in the remaining triangles, so that the pattern in the area is only effectively exposed once, and the remaining exposure times are all blocked, and the final exposure effect is equivalent to one exposure. 3. In the case where multiple exposures of effective graphics in the splicing area cannot be avoided, Scheme III achieves the optimal solution, and only the compensation design for the secondary exposure needs to be considered. 4. To facilitate the description of the method of this application, the example pattern used is a centrally symmetrical figure, and the splicing conditions in the X-axis (horizontal direction) and Y-axis (vertical direction) are consistent; the figure in actual conditions can be an irregular figure, and the splicing method of the present invention is also applicable. The difference is that the splicing design in the X-axis and Y-axis directions needs to be considered separately, and the complexity is different.

[0060] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A small-size mask splicing method, characterized by: The steps of the small-size mask splicing method are as follows: X = minimum line spacing that meets process requirements; Y = minimum overlap distance of shots that meets process requirements, splicing overlap area width F, blank distance A; When the blank distance A≥2X+Y, the conventional splicing steps are adopted: directly set the splicing overlap area F in area A; When the blank distance A is less than 2X+Y, the splicing steps of the blocking method are adopted: the splicing overlap area width F is set to be greater than or equal to 2X+B, where B is the overall width of the glass product pattern, i.e., the four exposure areas wrap the glass product pattern; the four exposure areas correspond to the four corners of the same main exposure area (1), the upper left corner area is taken to maintain the original pattern, and the other upper right corners, lower left corners, and lower right corners are all set with blocking blocks.

2. The small-size mask splicing method according to claim 1, wherein: When the blank distance A is less than 2X+Y and the stitching overlap area width F is limited to F<2X+B, the step-down exposure compensation method is used for stitching: valid graphics exist in both the overlapping second-exposure area and the fourth-exposure area. Conventional design requires separate second-exposure compensation and fourth-exposure compensation. In the step-down exposure compensation method, the fourth-exposure area is moved so that it is completely blank or completely filled with graphics.

3. The small-size mask splicing method according to claim 1, wherein: When the conventional stitching method is used, the double-exposure and quadruple-exposure areas are blank areas with no valid graphics, and no additional compensation design is required.

4. The small-size mask splicing method according to claim 1, wherein: When the blocking method is used for the splicing step, the blocking block is required to cover the pattern of the glass product and exceed the set distance; the secondary exposure area (2) is supplemented with the corresponding pattern or blocking block in the splicing overlap area and maintains the same placement rule as the main exposure area.

5. The small-size mask splicing method according to claim 2, wherein: When the blocking method is used for the stitching step, the pattern in the multiple exposure area is only effectively exposed once, and the remaining exposure times are all blocked, so that the final exposure effect is equivalent to a full exposure.

6. The small-size mask splicing method according to claim 5, characterized in that: When using the reduced exposure compensation method for stitching, the final exposure effect is independent of the number of exposures for areas with completely blank or completely filled graphics. Therefore, the four-exposure area no longer requires exposure compensation design. All graphics within the two-exposure area will have a two-exposure compensation block added.

7. The small-size mask splicing method according to claim 1 or 2, characterized in that: The actual effective exposure area of ​​the small-size mask is smaller than the glass size. In the mask, the area used for exposure is called a shot. To fully expose the entire glass, multiple shot arrays of small-size masks need to be spliced ​​together. The main exposure area (1) is used for product pattern exposure; the secondary exposure area (2) is used to supplement the main exposure shot pattern integrity and identify the alignment mark and test block exposure. There is a splicing overlap area width F between adjacent Shots.

8. The small-size mask splicing method according to claim 1 or 2, characterized in that: In the splicing mask, the four corners are the four exposure areas.

9. The small-size mask splicing method according to claim 1 or 2, characterized in that: The splicing mask includes an X-axis and a Y-axis.

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