Photomask manufacturing method for solving stripe and chromatic aberration defects
By exposing multiple times and adjusting the exposure starting point, the subtle stripes and chromatic aberration problems on the photomask plate are solved, and the quality and production efficiency of the photomask plate are improved.
Patent Information
- Application Number
- CN202411470955.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-07-29
Smart Images
Figure CN120386138A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photomasks, and particularly to a method for manufacturing a photomask for solving stripe and color difference defects. Background Art
[0002] A photomask is a graphic master used in the lithography process of microelectronics and integrated optoelectronics manufacturing. It is a high-precision tool for transferring graphic "negative films" during the manufacturing process of downstream industry products, and its quality directly affects the accuracy and quality of downstream products. A photomask forms a mask graphic structure on a transparent substrate with an opaque light-shielding film, and then transfers the graphic information to the product substrate through the exposure process. The existing methods for manufacturing photomasks generally include the following steps: (1) fabricating and generating a photomask layout file according to the circuit design; (2) coating a photoresist on a clean substrate, where the substrate usually consists of a glass / quartz substrate and a chromium layer; (3) importing the photomask layout file into a lithography machine, and the lithography machine exposes the substrate coated with the photoresist through an ultraviolet light spot; (4) after exposure, developing, etching, and cleaning are performed to obtain a photomask with the required graphic structure. However, during the exposure process, the light spot in the lithography machine is a circular spot with a fixed size. To ensure that the light spot covers the entire graphic during exposure, there is an overlapping area between adjacent light spots, as Figure 1 shown, resulting in multiple exposures in the overlapping area. After developing and etching the multiple-exposure area, fine stripes and color differences will be generated on the photomask, as Figure 2 shown, affecting the quality of the photomask. Summary of the Invention
[0003] The present invention provides a method for manufacturing a photomask for solving stripe and color difference defects. This method solves the problems of fine stripes and color difference defects in the existing photomask manufacturing method by means of multiple exposures and changing the exposure starting point, thereby improving the quality of the photomask.
[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows: A method for manufacturing a photomask for solving stripe and color difference defects, comprising the following steps: (1) Fabricating and generating a photomask layout file according to the circuit design; (2) Coating a photoresist on a clean substrate; (3) Import the photomask layout file into the lithography machine. The lithography machine performs N exposures (N≥3) on the substrate coated with photoresist through an ultraviolet light spot. The specific steps for N exposures are as follows: First exposure: Import the photomask layout file into the lithography machine. The outer frame size of the photomask layout file is X*Y. The lithography machine performs the first exposure on the substrate coated with photoresist through an ultraviolet light spot. Second exposure: Enlarge or reduce the outer frame size of the photomask layout file. The enlarged outer frame size is (X + 1 / N of the light spot diameter) * (Y + 1 / N of the light spot diameter), or the reduced outer frame size is (X - 1 / N of the light spot diameter) * (Y - 1 / N of the light spot diameter). Then import the photomask layout file with the enlarged or reduced outer frame size into the lithography machine. The lithography machine performs the second exposure on the substrate coated with photoresist through an ultraviolet light spot... Nth exposure: Enlarge or reduce the outer frame size of the photomask layout file. The enlarged outer frame size is [X + (N - 1) / N of the light spot diameter] * [Y + (N - 1) / N of the light spot diameter], or the reduced outer frame size is [X - (N - 1) / N of the light spot diameter] * [Y - (N - 1) / N of the light spot diameter]. Then import the photomask layout file with the enlarged or reduced outer frame size into the lithography machine. The lithography machine performs the Nth exposure on the substrate coated with photoresist through an ultraviolet light spot. When enlarging or reducing the outer frame size during the process from the second exposure to the Nth exposure, all steps are to enlarge the outer frame size simultaneously or reduce the outer frame size simultaneously. (4) After N exposures, perform development, etching, and cleaning to obtain the photomask with the desired graphic structure.
[0005] Preferably, 3≤N≤6.
[0006] Compared with the prior art, the beneficial effects of the present invention are as follows: By performing multiple exposures and changing the exposure starting point, the problems of fine stripes and color difference defects in the existing photomask manufacturing method are solved, and the quality of the photomask is improved. Description of the Drawings
[0007] Figure 1 It is a schematic diagram of the overlapping of exposure light spots during the manufacturing of the photomask in the prior art; Figure 2 It is a schematic diagram of the physical object of the stripes and color difference in the photomask in the prior art; Figure 3 It is a schematic diagram of the outer frame size of the photomask layout file during the first exposure in this embodiment; Figure 4 It is a schematic diagram of the outer frame size of the photomask layout file during the second exposure in this embodiment; Figure 5 It is a schematic diagram of the outer frame size of the photomask layout file during the third exposure in this embodiment; Figure 6Schematic diagram of the exposure circuit of the lithography machine in this embodiment; Figure 7 Schematic diagram of the overlap of the exposure spots in three exposures in this embodiment; Figure 8 Physical schematic diagram of the photomask manufactured by three exposures according to the manufacturing method in this embodiment; In the figure, 1 - graphic area, 2 - outer frame area, 3 - exposure starting point. Detailed implementation manners
[0008] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0009] A method for manufacturing a photomask to solve the defects of stripes and chromatic aberration, comprising the following steps: (1) Fabricate and generate a photomask layout file according to the circuit design; (2) Coat a photoresist on a clean substrate; (3) Import the photomask layout file into a lithography machine, and the lithography machine performs N exposures on the substrate coated with the photoresist through an ultraviolet light spot, where N≥3; considering efficiency and cost issues, preferably, 3≤N≤6, while solving the defects of stripes and chromatic aberration, ensuring the manufacturing efficiency of the photomask.
[0010] The specific steps of N - time exposure are as follows: First - time exposure: Import the layout file of the photomask into the lithography machine. The outer - frame size of the photomask layout file is X*Y. The lithography machine performs the first - time exposure on the substrate coated with photoresist through the ultraviolet light spot. Second - time exposure: Enlarge or reduce the outer - frame size of the photomask layout file. The enlarged outer - frame size is (X + 1 / N light - spot diameters)*(Y + 1 / N light - spot diameters) or the reduced outer - frame size is (X - 1 / N light - spot diameters)*(Y - 1 / N light - spot diameters). Then import the photomask layout file with the enlarged or reduced outer - frame size into the lithography machine. The lithography machine performs the second - time exposure on the substrate coated with photoresist through the ultraviolet light spot... N - th time exposure: Enlarge or reduce the outer - frame size of the photomask layout file. The enlarged outer - frame size is [X+(N - 1) / N light - spot diameters]*[Y+(N - 1) / N light - spot diameters] or the reduced outer - frame size is [X-(N - 1) / N light - spot diameters]*[Y-(N - 1) / N light - spot diameters]. Then import the photomask layout file with the enlarged or reduced outer - frame size into the lithography machine. The lithography machine performs the N - th time exposure on the substrate coated with photoresist through the ultraviolet light spot. During the process of enlarging or reducing the outer - frame size from the second - time exposure to the N - th time exposure, all steps are to enlarge the outer - frame size simultaneously or reduce the outer - frame size simultaneously. That is, when the enlarged outer - frame size at the second - time exposure is (X + 1 / N light - spot diameters)*(Y + 1 / N light - spot diameters), the enlarged outer - frame size at the N - th time exposure is [X+(N - 1) / N light - spot diameters]*[Y+(N - 1) / N light - spot diameters]; if the reduced outer - frame size at the second - time exposure is (X - 1 / N light - spot diameters)*(Y - 1 / N light - spot diameters), the reduced outer - frame size at the N - th time exposure is [X-(N - 1) / N light - spot diameters]*[Y-(N - 1) / N light - spot diameters].
[0011] After N - time exposure, develop, etch, and clean to obtain the photomask with the desired graphic structure.
[0012] In this embodiment, a total of three exposures are performed, that is, N = 3. The size of the photomask layout file at the first - time exposure is X*Y, as Figure 3 shown. The outer - frame size of the enlarged mask layout file at the second - time exposure is (X + 1 / 3 light - spot diameters)*(Y + 1 / 3 light - spot diameters), as Figure 4 shown. The outer - frame size of the enlarged mask layout file at the third - time exposure is (X + 2 / 3 light - spot diameters)*(Y + 2 / 3 light - spot diameters), as Figure 5 shown.
[0013] The mask layout file usually includes a middle graphic area 1 and a frame area 2 located around the graphic area. When the existing lithography machine exposes, it always starts from the lower left corner of the layout file, that is, the lower left corner of the frame area of the layout file is the exposure starting point 3. After the exposure starts, the exposure platform moves from bottom to top and from left to right until the exposure ends, as Figure 6 shown. Therefore, when the frame size is reduced or enlarged, the position of the exposure starting point changes together with the frame size. In this embodiment, the frame size of the enlarged mask layout file during the second exposure is (X + 1 / 3 of the spot diameter) * (Y + 1 / 3 of the spot diameter). Therefore, the position of the exposure starting point is offset by 1 / 3 of the spot diameter relative to the first exposure; during the third exposure, the frame size of the enlarged mask layout file is (X + 2 / 3 of the spot diameter) * (Y + 2 / 3 of the spot diameter). Therefore, the position of the exposure starting point is offset by 2 / 3 of the spot diameter relative to the first exposure, as Figure 7 shown. At this time, except for the frame area, the areas on the graphic area are exposed more than twice, and the stripe color difference is relatively reduced. As the number of exposures increases, N > 3, the stripes and color difference become weaker, thus solving the problems of fine stripes and color difference during the production of the photomask and improving the production quality of the mask. According to the above method, the physical schematic diagram of the photomask obtained by three exposures is as Figure 8 shown. Three exposures can effectively solve the problems of fine stripes and color difference on the photomask.
Claims
1. A method for manufacturing a photomask for solving stripe and color difference defects, characterized in that It includes the following steps: (1) Fabricate and generate a photomask layout file according to the circuit design; (2) Coat a photoresist on a clean substrate; (3) Import the photomask layout file into a lithography machine. The lithography machine performs N exposures (N≥3) on the substrate coated with the photoresist through an ultraviolet light spot. The specific steps for the N exposures are as follows: The first exposure: Import the photomask layout file into the lithography machine. The outer frame size of the photomask layout file is X*Y. The lithography machine performs the first exposure on the substrate coated with the photoresist through the ultraviolet light spot. The second exposure: Enlarge or reduce the outer frame size of the photomask layout file. The enlarged outer frame size is (X + 1 / N of the light spot diameter) * (Y + 1 / N of the light spot diameter) or the reduced outer frame size is (X - 1 / N of the light spot diameter) * (Y - 1 / N of the light spot diameter). Then import the photomask layout file with the enlarged or reduced outer frame size into the lithography machine. The lithography machine performs the second exposure on the substrate coated with the photoresist through the ultraviolet light spot... The Nth exposure: Enlarge or reduce the outer frame size of the photomask layout file. The enlarged outer frame size is [X + (N - 1) / N of the light spot diameter] * [Y + (N - 1) / N of the light spot diameter] or the reduced outer frame size is [X - (N - 1) / N of the light spot diameter] * [Y - (N - 1) / N of the light spot diameter]. Then import the photomask layout file with the enlarged or reduced outer frame size into the lithography machine. The lithography machine performs the Nth exposure on the substrate coated with the photoresist through the ultraviolet light spot. When enlarging or reducing the outer frame size during the process from the second exposure to the Nth exposure, all steps enlarge the outer frame size or reduce the outer frame size simultaneously; (4) After the N exposures, perform development, etching, and cleaning to obtain a photomask with the required graphic structure.
2. The method for manufacturing a photomask for solving the defects of stripes and color difference according to claim 1, characterized in that: 3≤N≤6。