A method for manufacturing a metal mask plate
By setting the width of the inner edge of the transition zone to be greater than the width of the outer edge in the photomask design, the inner edge is etched preferentially during etching, which solves the problem of scratching the effective area by the transition zone during etching and improves the yield of metal photomasks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MAGIC STAR TECHNOLOGY (NINGBO) CO LTD
- Filing Date
- 2023-05-19
- Publication Date
- 2026-05-29
AI Technical Summary
When making metal photomasks by etching, the transition area of the metal foil is prone to wobbling during the etching process, which can scratch the effective area and reduce the yield of the metal photomask.
The photomask design makes the inner edge of the transition area wider than the outer edge. During etching, the inner edge is etched first to avoid contact between the transition area and the effective area. The transition area is removed by etching to separate the metal foil and prevent damage to the effective area.
This improved the yield of metal photomasks, reduced scratches in the effective area, and enhanced the quality of the finished product during the preparation process.
Smart Images
Figure CN116736628B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photomask preparation technology, and specifically to a method for preparing a metal photomask. Background Technology
[0002] OLED, or Organic Light Emitting Diode, offers advantages over LCDs such as lighter weight, wider viewing angle, faster response time, lower temperature resistance, and higher luminous efficiency, making it a next-generation display technology. Organic electroluminescent thin films are typically fabricated using vacuum thermal evaporation, where organic semiconductor materials are heated in a vacuum environment, causing them to sublimate. This sublimation is then achieved by depositing a multilayered OLED structure onto a substrate using a metal mask with a specific pixel pattern. This process involves the continuous deposition of multiple materials, with an anode and cathode deposited at each end of the stack. During the evaporation process, a metal mask is used to deposit the emitting layer of the OLED device.
[0003] Currently, photomasks are manufactured using methods such as etching and electroforming. Among these, etching is the most widely used method for manufacturing precision metal photomasks. When using this method, the pattern on the photomask is transferred onto a metal foil through an etching process. Therefore, the photomask is an important tool in the etching process for manufacturing photomasks.
[0004] The effective area of the photomask contains the pattern to be generated onto the metal foil. After the pattern is generated onto the metal foil (i.e., forming the effective area of the metal foil), the patterned portion of the metal foil needs to be separated to obtain the finished metal photomask. To facilitate the separation of the metal photomask and the metal foil, a transition zone is typically formed outside the effective area of the photomask in related technologies. This transition zone is also formed outside the effective area of the metal foil during the fabrication of the metal photomask. After etching away the transition zone of the metal foil, the metal foil and the patterned metal photomask can be separated. However, during the etching process of the transition zone of the metal foil, the transition zone will oscillate due to the flow of the etching solution. During this oscillation, the side of the transition zone closest to the effective area of the metal foil is easily scratched, resulting in a low yield of the finished metal photomask. Summary of the Invention
[0005] This invention aims to address one of the technical problems in related technologies to a certain extent. To this end, this invention provides a method for preparing a metal mask template, which has the advantage of high yield.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for preparing a metal photomask includes the following steps:
[0008] S100, Select a metal foil; Treat the surface of the metal foil to obtain a clean metal foil;
[0009] S101, Apply photoresist; apply photoresist to both sides of the surface-treated metal foil, or apply photoresist to one side of the metal foil;
[0010] S102, Exposure; The metal foil is placed on an exposure machine, and the photoresist on the metal foil is exposed using a patterned photomask. The light irradiated by the exposure machine is projected onto the photoresist through the photomask described in this application, and the pattern on the photomask is transferred to the photoresist. The pattern includes an effective area and a transition area disposed outside the effective area, and the width of the inner edge of the transition area is greater than the width of the outer edge.
[0011] S103, Development; The exposed metal foil with photoresist is developed to remove some of the photoresist and precisely fabricate the desired pattern on the photoresist. When a negative photoresist is used, the exposed metal foil with negative photoresist is immersed in the developer. The parts that have been exposed to light will solidify and remain, while the parts that have not been exposed to light will be dissolved by the developer. The projected pattern will appear on the remaining negative photoresist. When a positive photoresist is used, the exposed metal foil with positive photoresist is immersed in the developer. The parts that have not been exposed to light will solidify and remain, while the parts that have been exposed to light will be dissolved by the developer. The projected pattern will appear on the remaining positive photoresist.
[0012] S104, wet etching; after development, some photoresist is removed, and the part of the metal foil not covered by photoresist will be etched when it comes into contact with the etching solution. The effective area and transition area on the photoresist are etched onto the metal foil, and the transition area formed on the metal foil is removed by etching to separate the effective area and the metal foil.
[0013] S105, Remove photoresist; Remove photoresist after etching is complete;
[0014] S106, obtain the effective area with the desired pattern, i.e., the metal mask.
[0015] In this invention, during the exposure step, light from the exposure machine passes through a photomask and projects the pattern on the photomask onto photoresist. The photomask pattern includes an effective area and a transition area located outside the effective area. After etching, the effective area and transition area on the photomask are formed on a metal foil coated with photoresist. The effective area of the metal foil is the metal photomask to be manufactured. The size of the metal foil is larger than the size of the metal photomask to be manufactured, so in addition to the effective area and transition area, the metal foil also includes excess ineffective area. The ineffective area is formed outside the transition area. After the transition area is separated from the metal foil by etching, the effective area is naturally separated from the metal foil as well, thus obtaining the finished metal photomask.
[0016] In the photomask used in this invention, the inner edge width of the transition region is greater than the outer edge width. Therefore, after the photomask pattern is projected onto the metal foil, a transition region with an inner edge width greater than the outer edge width will also be formed on the metal foil. The inner edge of the transition region connects to the effective area of the metal foil, and the outer edge of the transition region connects to the ineffective area of the metal foil. The transition region is constructed such that after its inner and outer edges are etched, the entire transition region detaches from the metal foil, thereby obtaining the desired effective area (i.e., the metal photomask). Specifically, as... Figure 2 As shown, the portion of the metal foil where the transition zone meets the effective zone is defined as the inner edge, and the portion of the metal foil where the transition zone meets the ineffective zone is defined as the outer edge.
[0017] Furthermore, the width of the inner edge of the transition zone in the photomask is greater than the width of the outer edge. Therefore, the transition zone formed on the metal foil also has a wider inner edge than the outer edge. During etching of the metal foil, because the inner edge is wider than the outer edge, the inner edge region is more open than the outer edge region. The exchange ratio of ions in the etching solution with the inner edge is greater than the exchange ratio with the outer edge, and the wider inner edge will be etched preferentially. Therefore, one side of the inner edge of the transition zone will separate from the effective region first, while the outer edge remains connected to the ineffective region of the metal foil. The transition zone is separated from the effective region but not from the ineffective region. Under the interference of the ineffective region, the transition zone will not scrape against the effective region due to the flow of the etching solution, preventing damage to the edge of the effective region. Moreover, the wide inner edge results in a large gap between the transition zone and the effective region after the inner edge is etched, further preventing the edge of the transition zone from contacting the edge of the effective region, thus improving the yield of metal photomask production.
[0018] Optionally, in step S102, the width of the inner edge of the transition region is 80–150 μm, and the width of the outer edge is 10–50 μm. The width of the outer edge is smaller than the width of the inner edge, so the inner edge will be etched first. This also increases the gap between the transition region and the effective region after etching, making the effective region less likely to be scratched by the transition region and improving the yield of the prepared metal mask.
[0019] Optionally, several dividing lines are also formed within the transition area, with each end of the dividing line connecting to the outer and inner edges of the transition area, respectively. These dividing lines divide the transition area into several smaller regions. Only the dividing lines need to be etched to separate all of these smaller regions from the metal foil, eliminating the need to etch the entire transition area and allowing for faster separation. It should be noted that dividing lines refer to etched lines that intersect both the outer and inner edges, not just etched lines along a single direction. Any etched line that connects the outer and inner edges and divides the transition area into multiple smaller regions should be included within the scope of this application.
[0020] Optionally, the transition zone can be constructed as a runway ring, with its inner and outer edges forming the transition zone. The two ends of the runway ring have arc-shaped structures, while the middle portion is straight. The inner and outer edges intersect at both ends of the transition zone, forming a closed transition zone. Alternatively, the transition zone can be constructed as a rectangle, in which case its two ends have rectangular structures, and the ends of the inner and outer edges are connected by longitudinal etching lines to form a closed transition zone, with the inner and outer edges arranged parallel to each other. Furthermore, when the length of the transition zone is equal to that of the metal foil, only parallel inner and outer edges may exist, without the need to form a closed area to be etched.
[0021] Optionally, the effective area and transition area of the photomask can be integrally molded, and both areas can be made of the same material. Of course, the transition area can also be fixed to the outside of the effective area by welding or other methods.
[0022] Optionally, the effective area is constructed as a rectangle, with transition areas distributed on both sides of the effective area. When this photomask is used to fabricate a metal mask, a rectangular effective area is also formed on the metal foil with photoresist, and transition areas are arranged on both sides of the effective area. After etching away the transition areas, a rectangular metal mask is obtained.
[0023] Optionally, the photomask has transparent and opaque areas. Light from the exposure machine shines onto the photomask through the transparent areas, while the opaque areas block the light, thus forming a pattern on the metal foil with photoresist.
[0024] Optionally, in step S104, the metal foil also includes an invalid region located outside the transition region. The invalid region is excess material, and it needs to be removed during the etching process to separate the required effective region.
[0025] Optionally, the metal mask obtained in step S106 has several through holes. The through holes are formed by etching, and when the metal mask is subsequently used to produce devices such as displays, the evaporated light-emitting material is deposited through the through holes to form a light-emitting layer.
[0026] Optionally, the photomask is prepared using a process including the following steps:
[0027] S200: Select a light-transmitting substrate and clean the surface of the substrate;
[0028] S201, a chromium metal layer is plated on the substrate;
[0029] S202, a pattern with an effective area and a transition area is formed on a chromium metal layer, and the chromium metal layer covers part of the substrate;
[0030] S203, Obtain the required photomask.
[0031] Specifically, the substrate is made of quartz glass or soda glass, etc. This method for preparing the photomask is simple, low-cost, and produces a high yield of photomasks.
[0032] Optionally, in step S202, a pattern having an effective area and a transition area is drawn on the chromium metal layer using a drawing machine. Of course, a pattern having an effective area and a transition area can also be formed on the chromium metal layer by means of etching or the like.
[0033] 1. The photomask used in this invention has an effective region and a transition region. During the production of the metal photomask, the effective region and transition region can also be formed on the metal foil with photoresist. Since the size of the metal foil is larger than the size of the metal photomask to be manufactured, the metal foil also has an ineffective region located outside the transition region. That is, the transition region on the metal foil is located between the effective region and the ineffective region. Etching away the transition region in the middle separates the effective region and the ineffective region of the metal foil. The effective region is the metal photomask to be manufactured.
[0034] 2. The transition area on the photomask has inner and outer edges, so the transition area on the metal foil also has inner and outer edges. The inner edge of the transition area on the metal foil connects to the effective area of the metal foil, while the outer edge connects to the ineffective area. Etching away the inner and outer edges will detach the transition area from the metal foil.
[0035] 3. Since the width of the inner edge is greater than that of the outer edge, the inner edge is more likely to react with the ions in the etching solution. Therefore, the inner edge is preferentially etched. When one side of the inner edge of the transition region separates from the effective region, the other side of the outer edge remains connected to the ineffective region. Under the interference of the ineffective region, the transition region will not come into contact with the effective region, thus improving the yield of the prepared metal mask.
[0036] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. The preferred embodiments or means of the present invention will be shown in detail in conjunction with the accompanying drawings, but are not intended to limit the technical solutions of the present invention. In addition, each of these features, elements and components appearing in the following text and drawings is a plurality of, and different symbols or numbers are used for convenience of representation, but all represent parts with the same or similar construction or function. Attached Figure Description
[0037] The present invention will be further described below with reference to the accompanying drawings:
[0038] Figure 1 This is a process flow diagram for manufacturing the metal mask template in this invention;
[0039] Figure 2 This is a diagram showing the fit between the photomask and the metal foil in this invention;
[0040] Figure 3This is a schematic diagram of the photomask structure in this invention;
[0041] Figure 4 for Figure 3 A schematic diagram of the structure at point A in the middle.
[0042] Among them, 1. Photomask; 11. Body; 111. Effective area; 112. Transition area; 1121. Inner edge; 1122. Outer edge; 1123. Separator line; 2. Metal foil. Detailed Implementation
[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described are intended to explain the present invention and should not be construed as limiting the invention.
[0044] The terms "an embodiment," "example," or "trademark" used in this specification refer to a particular feature, structure, or characteristic described in connection with the embodiment itself that may be included in at least one embodiment disclosed in this patent. The phrase "in an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.
[0045] Example 1:
[0046] This embodiment provides, as follows: Figure 1 The method for preparing a metal mask template includes the following steps:
[0047] S100, Select a metal foil 2 with high flatness; Treat the surface of the metal foil 2 to obtain a clean metal foil 2;
[0048] S101, Apply photoresist; Apply photoresist to both sides of the surface-treated metal foil 2;
[0049] S102, Exposure; Place the metal foil 2 on the exposure machine, such as Figure 2 As shown, a patterned photomask 1 is used to expose photoresist on a metal foil 2. The photomask 1 includes a rectangular body 11. Light irradiated by the exposure machine passes through the body 11 and is projected onto the photoresist, transferring the pattern on the photomask 1 onto the photoresist; as shown... Figure 3 and Figure 4As shown, the pattern includes an effective area 111 and a transition area 112 disposed outside the effective area 111. The width of the inner edge 1121 of the transition area 112 is greater than the width of the outer edge 1122. Specifically, the width of the inner edge 1121 is 100 μm and the width of the outer edge 1122 is 10 μm. In addition, multiple dividing lines 1123 are formed between the inner edge 1121 and the outer edge 1122 of the transition area 112 of the photomask 1. The two ends of the dividing lines 1123 are connected to the inner edge 1121 and the outer edge 1122 respectively, dividing the transition area 112 into several small regions.
[0050] S103, Development; The exposed metal foil 2 with photoresist is developed to remove some of the photoresist and to accurately fabricate the desired pattern on the photoresist; Specifically, the photoresist used is a negative photoresist. The exposed metal foil 2 with negative photoresist is immersed in the developing solution. The parts that have been exposed to light will solidify and remain, while the parts that have not been exposed to light will be dissolved by the developing solution, and the projected pattern will appear on the remaining negative photoresist.
[0051] S104, wet etching; after development, part of the photoresist is removed, and the part of the metal foil 2 not covered by photoresist will be etched when it comes into contact with the etching solution. The effective area 111 and the transition area 112 on the photoresist are etched onto the metal foil 2, and the transition area 112 formed on the metal foil 2 is removed by etching to separate the effective area 111 and the metal foil 2. Since the width of the inner edge 1121 of the transition area 112 of the photomask 1 is greater than the width of the outer edge 1122, the width of the inner edge 1121 of the transition area 112 of the metal foil 2 is also greater than the width of the outer edge 1122. The inner edge 1121 is etched before the outer edge 1122. When the inner edge 1121 is etched, the outer edge 1122 is still connected to the ineffective area of the metal foil 2, which can prevent the transition area 112 from scratching the edge of the effective area 111 as the etching solution flows.
[0052] S105, Remove photoresist; Remove photoresist after etching is complete;
[0053] S106, Obtain a metal mask with the desired pattern.
[0054] The yield of the prepared metal mask was tested, and the test results are shown in Table 1.
[0055] Comparative Example 1:
[0056] This comparative example provides a method for preparing a metal photomask. The difference between this embodiment and Example 1 is that the structure of the photomask 1 used is different; the other steps are basically the same. This embodiment includes the following steps:
[0057] S100, Select metal foil 2; Treat the surface of metal foil 2 to obtain clean metal foil 2;
[0058] S101, Apply photoresist; Apply photoresist to both sides of the surface-treated metal foil 2;
[0059] S102, Exposure; The metal foil 2 is placed on an exposure machine, and the photoresist on the metal foil 2 is exposed using a patterned photomask 1. The photomask 1 includes a rectangular body 11. The light irradiated by the exposure machine passes through the body 11 and is projected onto the photoresist, and the pattern on the photomask 1 is transferred to the photoresist. The pattern includes an effective area 111 and a transition area 112 disposed outside the effective area 111. The width of the inner edge 1121 of the transition area 112 is equal to the width of the outer edge 1122. Specifically, the width of the inner edge 1121 is 10 μm, and the width of the outer edge 1122 is 10 μm. In addition, a plurality of dividing lines 1123 are formed between the inner edge 1121 and the outer edge 1122 of the transition area 112 of the photomask 1. The two ends of the dividing lines 1123 are connected to the inner edge 1121 and the outer edge 1122 respectively, dividing the transition area 112 into several small regions.
[0060] S103, Development; The exposed metal foil 2 with photoresist is developed to remove some of the photoresist and to accurately fabricate the desired pattern on the photoresist.
[0061] S104, wet etching; the effective area 111 and the transition area 112 on the photoresist are etched onto the metal foil 2, and the transition area 112 formed on the metal foil 2 is removed by etching to separate the effective area 111 and the metal foil 2; since the width of the inner edge 1121 of the transition area 112 of the photomask 1 is equal to the width of the outer edge 1122, the width of the inner edge 1121 of the transition area 112 of the metal foil 2 is also equal to the width of the outer edge 1122, and the inner edge 1121 and the outer edge 1122 are etched at the same time;
[0062] S105, Remove photoresist; Remove photoresist after etching is complete;
[0063] S106, Obtain a metal mask with the desired pattern.
[0064] The yield of the prepared metal mask was tested, and the test results are shown in Table 1.
[0065] Comparative Example 2:
[0066] This comparative example provides a method for preparing a metal photomask. The difference between this embodiment and Comparative Example 1 is that the widths of the inner edge 1121 and outer edge 1122 of the transition region 112 of the photomask 1 are different; the other steps are basically the same. This embodiment includes the following steps:
[0067] S100, Select metal foil 2; Treat the surface of metal foil 2 to obtain clean metal foil 2;
[0068] S101, Apply photoresist; Apply photoresist to both sides of the surface-treated metal foil 2;
[0069] S102, Exposure; The metal foil 2 is placed on an exposure machine, and the photoresist on the metal foil 2 is exposed using a patterned photomask 1. The photomask 1 includes a rectangular body 11. The light irradiated by the exposure machine passes through the body 11 and is projected onto the photoresist, and the pattern on the photomask 1 is transferred to the photoresist. The pattern includes an effective area 111 and a transition area 112 disposed outside the effective area 111. The width of the inner edge 1121 of the transition area 112 is equal to the width of the outer edge 1122. Specifically, the width of the inner edge 1121 is 100μm, and the width of the outer edge 1122 is 100μm. In addition, a plurality of dividing lines 1123 are formed between the inner edge 1121 and the outer edge 1122 of the transition area 112 of the photomask 1. The two ends of the dividing lines 1123 are connected to the inner edge 1121 and the outer edge 1122 respectively, dividing the transition area 112 into several small regions.
[0070] S103, Development; The exposed metal foil 2 with photoresist is developed to remove some of the photoresist and to accurately fabricate the desired pattern on the photoresist.
[0071] S104, wet etching; the effective area 111 and the transition area 112 on the photoresist are etched onto the metal foil 2, and the transition area 112 formed on the metal foil 2 is removed by etching to separate the effective area 111 and the metal foil 2; since the width of the inner edge 1121 of the transition area 112 of the photomask 1 is equal to the width of the outer edge 1122, the width of the inner edge 1121 of the transition area 112 of the metal foil 2 is also equal to the width of the outer edge 1122, and the inner edge 1121 and the outer edge 1122 are etched at the same time;
[0072] S105, Remove photoresist; Remove photoresist after etching is complete;
[0073] S106, Obtain a metal mask with the desired pattern.
[0074] The yield of the prepared metal mask was tested, and the test results are shown in Table 1.
[0075] Table 1: Test results of the inner and outer edge width of photomask 1 and the yield of metal photomask in Example 1, Comparative Example 1 and Comparative Example 2
[0076]
[0077] As shown in Table 1, in Example 1, when the width of the inner edge 1121 of the transition region 112 of the photomask 1 is greater than the width of the outer edge 1122, the inner edge 1121 of the transition region 112 generated on the metal foil 2 is etched first. During etching, the transition region 112 of the metal foil 2 is less likely to scratch the effective area 111, thus greatly improving the yield of the metal photomask. In Comparative Example 1, the widths of the inner edge 1121 and the outer edge 1122 of the photomask 1 are equal and relatively small, meaning that the inner edge 1121 of the transition region 112 generated on the metal photomask is closer to the effective area 111, and the transition region 112... When the inner edge 1121 and the outer edge 1122 are etched simultaneously, the yield of the metal mask decreases. In Comparative Example 2, the width of the inner edge 1121 and the width of the outer edge 1122 of the photomask 1 are equal and the value is large. That is, the inner edge 1121 and the outer edge 1122 of the transition area 112 generated on the metal mask are etched simultaneously. Therefore, the yield of the metal mask is lower than that of the metal mask obtained in Example 1. However, since the inner edge 1121 of the transition area 112 is far from the effective area 111, the yield of Comparative Example 2 is still greater than that of the metal mask in Comparative Example 1.
[0078] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.
Claims
1. A method for preparing a metal photomask, characterized in that, Includes the following steps: S100, metal foil material is selected; S101, Apply photoresist; S102, Exposure; The photoresist on the metal foil is exposed using a patterned photomask, so that the pattern is transferred onto the photoresist; The pattern includes an effective area and a transition area disposed outside the effective area. The width of the inner edge of the transition area is greater than the width of the outer edge. The width of the inner edge of the transition area is 80~150μm, and the width of the outer edge is 10~50μm. S103, Development; The exposed metal foil with photoresist is developed to remove some of the photoresist and to accurately create the desired pattern on the photoresist. S104, wet etching; etching the effective area and transition area on the photoresist onto the metal foil, and removing the transition area formed on the metal foil by etching to separate the effective area and the metal foil. S105, Remove photoresist; Remove photoresist after etching is complete; S106, Obtain a metal mask with the desired pattern.
2. The preparation method according to claim 1, characterized in that, Several dividing lines are also formed within the transition zone, with the two ends of each dividing line connecting to the outer and inner edges of the transition zone, respectively.
3. The preparation method according to claim 1, characterized in that, The transition zone is constructed as a runway ring, with the inner and outer edges forming the transition zone.
4. The preparation method according to claim 1, characterized in that, The transition zone is constructed as a rectangle, with its inner and outer edges set parallel to each other.
5. The preparation method according to claim 1, characterized in that, The effective area is constructed as a rectangle, with transition areas distributed on both sides of the effective area.
6. The preparation method according to claim 1, characterized in that, In step S104, the metal foil also includes an invalid region located outside the transition region.
7. The preparation method according to claim 1, characterized in that, The metal mask obtained in step S106 has several through holes.
8. The preparation method according to claim 1, characterized in that, The photomask is prepared using a process including the following steps: S200, a light-transmitting substrate is selected; S201, a chromium metal layer is plated on the substrate; S202, forming a pattern with an effective area and a transition area on a chromium metal layer; S203, Obtain the required photomask.
9. The preparation method according to claim 8, characterized in that, In step S202, a pattern with an effective area and a transition area is formed on the chromium metal layer by a drawing machine or etching.