Photomask, metal mask and preparation method

Abstract

The invention relates to the technical field of display, and provides a photomask, a metal mask plate and a preparation method, the photomask comprises a pattern definition area, the pattern definition area is used for defining a pixel opening area of the metal mask plate, the pattern definition area is a closed pattern formed by four concave arcs and fillets connected with the concave arcs, the pixel opening area is a rounded rectangle, the center of the graph definition area coincides with the center of the pixel opening area, and the area of the graph definition area is smaller than that of the pixel opening area. The pattern of the pattern definition area transferred on the metal mask can enable the liquid medicine to be more uniformly distributed on the whole surface, effectively reduce the formation of eddy current and dead zones, and avoid the retention of the liquid medicine in a local area, thereby reducing the problems of impurity accumulation and incomplete reaction, reducing inconsistent etching caused by non-uniform flow, and improving the etching quality. Therefore, the etching uniformity of the fillet and the etching uniformity of the straight edge of the pixel opening area of the metal mask plate are improved.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a photomask, a metal mask and a preparation method thereof. Background Art

[0002] In the field of display technology, FMM (Fine Metal Mask) is a key material used in the manufacture of OLED (organic light-emitting diode) panels. It is primarily used in the vacuum evaporation process. RGB (red, green, and blue) sub-pixel materials are deposited onto the display panel through the pixel openings on the FMM, enabling high-resolution displays.

[0003] When making FMM, the pixel opening area needs to be defined by the pattern on the mask, and then the opening area is etched out by wet etching. Figure 1 When the pixel opening area in the required FMM is a rounded rectangle, if the pattern on the mask is a normal rectangle, the 90° right angle will cause the solution to be unable to etch the rounded corners of the pixel opening area in place. Therefore, the pattern on the existing mask is Figure 1 The closed pattern consists of four linear convex corner structures and four straight edges, but this mask pattern still limits the actual production space of the rounded corners in the pixel opening area, because this linear convex corner structure will cause the streamlines to suddenly change at right angles or sharp corners or at the intersection of two straight lines when the liquid flows, which is easy to form eddies and dead zones, resulting in uneven flow. The four rounded corners may have different radii, and the four straight edges may also be etched unevenly. During the etching process, the uniformity of the rounded corners and straight edges in the pixel opening area of ​​the FMM product cannot be effectively guaranteed.

[0004] Therefore, it is now necessary to solve the problem of poor uniformity of rounded corners and straight edges in the pixel opening area of ​​FMM products. Summary of the Invention

[0005] The object of the present invention is to provide a photomask, a metal mask and a preparation method thereof, so as to solve the technical problem of poor internal uniformity of the pattern in the pixel opening area of ​​the FMM product existing in the prior art.

[0006] In the first aspect, an embodiment of the present invention provides a mask, comprising: a graphic definition area, wherein the graphic definition area is used to define a pixel opening area of ​​a metal mask, wherein the graphic definition area is a first closed figure composed of four concave arcs and rounded corners connecting the concave arcs, and the pixel opening area is a first rounded rectangle, wherein the first closed figure coincides with the center of the first rounded rectangle and the area of ​​the first closed figure is smaller than the area of ​​the first rounded rectangle.

[0007] Furthermore, the length of the short side of the graphic definition area is taken as the first critical dimension, and the distance between the midpoint of the arc of the rounded corner of the graphic definition area and the midpoint of the arc of the rounded corner of the pixel opening area is taken as the first distance. When the first critical dimension is greater than or equal to 25 microns and less than or equal to 45 microns, the first distance is greater than or equal to one-fifth of the first critical dimension and less than one-half of the first critical dimension; when the first critical dimension is greater than 45 microns and less than or equal to 80 microns, the first distance is greater than or equal to one-eighth of the first critical dimension and less than one-third of the first critical dimension.

[0008] Furthermore, when the first critical dimension is greater than or equal to 25 microns and less than or equal to 45 microns, the first distance is a first length; when the first critical dimension is greater than 45 microns and less than or equal to 80 microns, the first distance is a second length; the first length is greater than the second length.

[0009] Furthermore, the fillet radius of the graphic definition area is the difference between the fillet radius of the pixel opening area and the first distance.

[0010] Furthermore, the arc length of the rounded corner of the graphic definition area is one quarter of the circle.

[0011] Furthermore, the distance between the midpoint of the concave arc and the midpoint of the line between the endpoints of the two adjacent rounded corners is taken as the second distance, and the length of the edge of the pixel opening area corresponding to the concave arc is taken as the second critical dimension, and the second distance increases logarithmically with the second critical dimension.

[0012] Further, when the second critical dimension is greater than or equal to 25 microns and less than or equal to 40 microns, the second distance is the first recess depth; when the second critical dimension is greater than or equal to 40 microns and less than or equal to 50 microns, the second distance is the second recess depth; when the second critical dimension is greater than or equal to 50 microns and less than or equal to 80 microns, the second distance is the third recess depth.

[0013] Furthermore, the first recessed depth is smaller than the second recessed depth, which is smaller than the third recessed depth.

[0014] In a second aspect, an embodiment of the present invention further provides a metal mask, which is prepared using the photomask as described in any of the preceding items.

[0015] In a third aspect, an embodiment of the present invention further provides a method for preparing a metal mask, wherein the metal mask is prepared using the photomask as described in any of the preceding items, and is subsequently etched using a wet etching process.

[0016] The embodiments of the present invention have at least the following technical effects: A photomask provided by an embodiment of the present invention is used in an exposure machine to produce a metal mask. The photomask includes multiple densely distributed pattern definition areas, which are used to define the pixel opening areas of the metal mask. The pattern definition areas are areas that are impermeable to light. After exposure, the pattern of the pattern definition areas is left on the metal mask. Then, through wet etching, the pixel opening areas are etched out by an etching agent. Therefore, the centers of the pattern definition areas and the pixel opening areas coincide with each other. Moreover, due to the non-directional corrosiveness of the etching solution, the wet etching method results in a pixel opening area with a larger opening area than the pattern definition areas. Because the pixel opening area of ​​the metal mask to be produced is a rounded rectangular area, the pattern of the pattern definition areas is a closed figure consisting of four inward-concave arcs and the rounded corners connecting the inward-concave arcs. The rounded corners connecting the inward-concave arcs are the first rounded corners.

[0017] During the wet etching process, the closed pattern formed by the concave arc transferred onto the metal mask and the first rounded corner can distribute the liquid more evenly across the entire surface, effectively reducing the formation of eddies and dead zones, and preventing the liquid from being retained in local areas, thereby reducing the problems of impurity accumulation and incomplete reactions, and reducing etching inconsistencies caused by uneven flow, thereby improving the etching uniformity of the rounded corners in the pixel opening area and the etching uniformity of the straight edges. At the same time, by combining the concave arc with the first rounded corner, this solution increases the manufacturing space for the rounded corners in the pixel opening area, and also solves the space limitation problem caused by the convex corner structure in the prior art. By optimizing the structural design of the graphic definition area, the manufacturing space and uniformity of the rounded corners in the pixel opening area and the uniformity of the straight edges are ensured, significantly improving the performance and yield of the metal mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the prior art provided by the present invention; Figure 2 A schematic structural diagram of a photomask provided by an embodiment of the present invention; Figure 3 A schematic diagram of the relationship between the fillet sizes of a photomask provided by an embodiment of the present invention; Figure 4 A schematic diagram of the inner concave arc and concave relationship of a first structure of a photomask provided by an embodiment of the present invention; Figure 5A schematic diagram of the inner concave arc and concave relationship of a second structure of a photomask provided by an embodiment of the present invention.

[0020] Icons: 1-Graphic definition area; 2-Pixel opening area; 11-Concave arc; 12-First rounded corner; 21-Second straight edge; 22-Second rounded corner. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless specifically defined as such, will not be interpreted in an idealized or overly formal sense.

[0023] It will be understood by those skilled in the art that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. The term "and / or" used herein includes all or any one of the associated listed items and all combinations thereof.

[0024] For the first aspect, see Figures 2 to 5 An embodiment of the present invention provides a photomask, comprising: a graphic definition area 1, the graphic definition area 1 being used to define a pixel opening area 2 of a metal mask; the graphic definition area 1 being a closed graphic composed of four inwardly concave arcs 11 and rounded corners connecting the inwardly concave arcs 11; the pixel opening area 2 being a rounded rectangle; the centers of the graphic definition area 1 and the pixel opening area 2 coincide with each other, and the area of ​​the graphic definition area 1 being smaller than that of the pixel opening area 2.

[0025] In this embodiment, a photomask is used in an exposure machine to produce a metal mask. The photomask includes a plurality of densely distributed pattern definition areas 1, which are used to define the pixel opening areas 2 of the metal mask. The pattern definition areas 1 can be understood as areas that are impermeable to light. After exposure, the pattern of the pattern definition areas 1 is left on the metal mask. Then, through wet etching, the pixel opening areas 2 are etched out by the etching agent. Therefore, the centers of the pattern definition areas 1 and the pixel opening areas 2 coincide with each other. Due to the non-directional corrosiveness of the wet etching solution, the wet etching process results in pixel opening areas 2 having a larger opening area than the pattern definition areas 1. Since the pixel opening areas 2 of the metal mask to be produced are rounded rectangles, the pattern of the pattern definition areas 1 is a closed figure consisting of four inwardly concave arcs 11 and the rounded corners connecting the inwardly concave arcs 11. The rounded corners connecting the inwardly concave arcs 11 are first rounded corners 12.

[0026] During the wet etching process, the closed pattern formed by the concave arc 11 and the first rounded corner 12 transferred on the metal mask can make the liquid more evenly distributed over the entire surface, effectively reducing the formation of eddies and dead zones, and preventing the liquid from being retained in local areas, thereby reducing the problems of impurity accumulation and incomplete reaction, and reducing the etching inconsistency caused by uneven flow, thereby improving the etching uniformity of the rounded corners of the pixel opening area 2 and the etching uniformity of the straight edges. At the same time, by combining the concave arc 11 with the first rounded corner 12, this solution increases the manufacturing space for the rounded corners of the pixel opening area 2, and also solves the space limitation problem caused by the convex corner structure in the prior art. By optimizing the structural design of the graphic definition area 1, the manufacturing space and uniformity of the rounded corners of the pixel opening area 2 and the uniformity of the straight edges are ensured, significantly improving the performance and yield of the metal mask.

[0027] Optional, see Figure 3 The length of the short side of the pixel opening area 2 is taken as the first critical dimension D1, and the distance between the midpoint of the arc of the rounded corner of the graphic definition area 1 and the midpoint of the arc of the rounded corner of the pixel opening area 2 is taken as the first distance X1. When the first critical dimension D1 is greater than or equal to 25 microns and less than or equal to 45 microns, the first distance X1 is greater than or equal to one-fifth of the first critical dimension D1 and less than or equal to one-half of the first critical dimension D1; when the first critical dimension D1 is greater than 45 microns and less than or equal to 80 microns, the first distance X1 is greater than or equal to one-eighth of the first critical dimension D1 and less than or equal to one-third of the first critical dimension D1.

[0028] In this embodiment, the length of the short side of the pixel opening area 2 is required to be the first critical dimension D1. Note that the short side here does not mean that the pixel opening area 2 is only the short side of the rounded rectangle, for example Figure 3The pixel opening area 2 in it is a rounded rectangle. At this time, the first key dimension D1 is the length where the short side of the rounded rectangle is located, and Figure 2 the pixel opening area 2 in it is a rounded square. Since any side of the rounded square is equally short, at this time, the first key dimension D1 is the length where any side of the rounded square is located. The rounded corners of the graphic definition area 1 are the first rounded corners 12, and the rounded corners of the pixel opening area 2 are the second rounded corners 22. The distance between the arc midpoints of the first rounded corners 12 and the corresponding arc midpoints of the second rounded corners 22 is defined as the first distance X1. If a metal mask plate is to be prepared, that is, the first key dimension D1 of the pixel opening area 2 on the target metal mask plate is between 25 and 80 microns, then the first distance X1 needs to follow the following rules. When 25μm ≤ D1 ≤ 45μm, D1 ≤ X1 ≤ D1; when 45μm < D1 ≤ 80μm, D1 ≤ X1 ≤ D1. For example, when the first key dimension D1 is 45μm, the first distance X1 is selected between 9μm - 22.5μm. Accordingly, the positions of the arc midpoints of the four rounded corners of the graphic definition area 1 on the reticle can also be determined. When the first distance X1 follows the above rules, the required transfer pattern on the metal mask plate can be prepared according to the graphic definition area 1 on the reticle, and then the size of the pixel opening area 2 on the target metal mask plate can be etched based on this.

[0029] Optionally, when the first key dimension D1 is greater than or equal to 25 microns and less than or equal to 45 microns, the first distance X1 is the first length; when the first key dimension D1 is greater than 45 microns and less than or equal to 80 microns, the first distance X1 is the second length; the first length is greater than the second length.

[0030] In this embodiment, when following the aforementioned value range of X1, the selection of the first distance X1 can be made according to the following value-taking method, that is, when 25μm ≤ D1 ≤ 45μm, the first distance X1 can be the same length. At this time, the value range of the first distance X1 should take the intersection of the value ranges when the first key dimension is 25μm and 45μm respectively; when 45μm < D1 ≤ 80μm, the first distance X1 can be the same length. At this time, the value range of the first distance X1 should take the intersection of the value ranges when the first key dimension is greater than 45μm and 80μm respectively. The advantage of taking the same length is that it can reduce the links generating variables, increase the reliability of the design, unify the rule consensus in production, and increase the quality stability of the product. Preferably, the first length should be greater than the second length, and the size of the first distance when 25μm ≤ D1 ≤ 45μm is less than the size of the first distance when 45μm < D1 ≤ 80μm, so as to ensure better etching effect.

[0031] Optionally, the fillet radius of the pattern definition area 1 is the difference between the fillet radius of the pixel opening area 2 and the first distance X1. In this embodiment, the radius of the first fillet 12 is the difference between the fillet radius of the pixel opening area 2 and the first distance X1. The first fillet 12 and the fillet of the pixel opening area 2 have the same center. This is to ensure uniform etching of the second fillet 22 under the action of the wet etching solution.

[0032] Optionally, the arc length of the rounded corner of the graphic definition area 1 is one-quarter of the circle. In this embodiment, the arc length of the first rounded corner 12 is one-quarter of the circle whose radius is the difference between the rounded corner radius of the second rounded corner 22 and the first distance X1. This ensures uniform etching of the rounded corner of the pixel opening area 2 and more uniform flow of the chemical solution between the first rounded corner 12 and the concave arc 11. The straight edge of the pixel opening area 2 is the second straight edge 21, which also ensures that the second straight edge 21 can be evenly etched by the chemical solution.

[0033] Optionally, the distance between the midpoint of the concave arc 11 and the midpoint of the line connecting the endpoints of two adjacent first rounded corners 12 is the second distance, so each concave arc 11 has its corresponding concave depth, i.e., the second distance, and the second key dimension is the length of the side of the pixel opening area 2 corresponding to the concave arc 11. Figure 4 As shown, if the pixel opening area 2 is a rounded rectangle, the depth of the concave arc 11, i.e., the second distance, includes X21 and X22, and the corresponding second critical dimensions are D21 and D22. Figure 5 As shown, if the pixel opening area 2 is a rounded square, the concave depths of the concave arcs 11 are the same, that is, the second distance X2 is the same, and the second critical dimension D2 is also the same.

[0034] Optionally, the second distance X2 grows logarithmically with the second critical dimension D2. In this embodiment, the depth of the concave arc 11 and the length of the side of the corresponding pixel opening area show a logarithmic growth trend. Regardless of whether the pixel opening area 2 is a rounded rectangle, the second distances X21 and X22 follow a logarithmic growth trend with the second critical dimensions D21 and D22 respectively; or whether the pixel opening area 2 is a rounded square, the second distance X2 follows a logarithmic growth rule with the second critical dimension D2. Specifically, with the second critical dimension as the independent variable x and the second distance as the dependent variable y, the growth relationship between the second critical dimension and the second distance is: y=a*ln(x)-b, where 0.55≤a≤0.65 and 1.4≤b≤1.6, ensuring that the straight edges of the pixel opening area 2 can also be uniformly etched.

[0035] Optionally, when the second critical dimension is greater than or equal to 25 μm and less than 40 μm, the second distance is the first recess depth; when the second critical dimension is greater than or equal to 40 μm and less than or equal to 50 μm, the second distance is the second recess depth; when the second critical dimension is greater than 50 μm and less than or equal to 80 μm, the second distance is the third recess depth.

[0036] In this embodiment, taking the pixel opening region 2 as a rounded square as an example, if the second critical dimension 25 μm ≤ D2 < 40 μm, then the second distance X2 is the first recess depth. That is to say, when the second critical dimension D2 is 25 μm and when the second critical dimension D2 is 39 μm, the recess of the inner concave arc 11, that is, the second distance X2, can be the same value. At this time, the value range of the first distance X2 should take the intersection of the value ranges of the above second critical dimension D2 at 25 μm and less than 40 μm respectively; if the second critical dimension 40 μm ≤ D2 ≤ 50 μm, then the second distance X2 is the second recess depth. For example, when the second critical dimension D2 is 40 μm and when the second critical dimension D2 is 50 μm, the recess of the inner concave arc 11, that is, the second distance X2, can be the same value. At this time, the value range of the first distance X2 should take the intersection of the value ranges of the above second critical dimension D2 at 40 μm and 50 μm respectively; if the second critical dimension 50 μm < D2 ≤ 80 μm, then the second distance X2 is the third recess depth. For example, when the second critical dimension D2 is 51 μm and when the second critical dimension D2 is 50 μm, the recess of the inner concave arc 11, that is, the second distance X2, can be the same value. At this time, the value range of the first distance X2 should take the intersection of the value ranges of the above second critical dimension D2 greater than 50 μm and 80 μm respectively.

[0037] Optionally, the first recess depth is less than the second recess depth is less than the third recess depth. In this embodiment, since the larger the second critical dimension D2, the larger the recess of the inner concave arc can be, so when taking values, the first recess depth is less than the second recess depth is less than the third recess depth, so as to ensure better etching effect.

[0038] In the second aspect, the embodiment of the present invention provides a metal mask plate, which is prepared by using the photomask as described above. The above photomask is applied to an exposure machine to transfer a corresponding pattern onto the metal mask plate, thereby obtaining a corresponding pixel opening region.

[0039] Optionally, the material of the metal mask plate includes invar alloy. In this embodiment, because the material of the metal mask plate is invar alloy, the photomask in the first aspect needs to be used to prepare a corresponding pixel opening region according to the design rules of the graphic definition region.

[0040] The metal mask in this embodiment is prepared by using the photomask in the first aspect. For details not included in this embodiment, please refer to the first aspect and Figures 2 to 5 The detailed description is omitted here.

[0041] In a third aspect, embodiments of the present invention provide a method for preparing a metal mask, using the above-described photomask preparation method and subsequently performing etching using a wet etching process. The metal mask in this embodiment is exposed using the photomask described in the first aspect and then subsequently etched using a wet etching process to obtain the desired pixel opening area. The wet etching process can be performed directly after exposure, or a process such as cleaning can be added between exposure and wet etching that does not alter the pattern composed of the concave arc and the first rounded corner transferred to the metal mask and does not react with the photoresist or the metal mask itself.

[0042] The preparation method of the metal mask in this embodiment adopts the preparation method of the photomask in the first aspect. For details not included in this embodiment, please refer to the first aspect and Figures 2 to 5 The detailed description is omitted here.

[0043] Those skilled in the art will appreciate that the steps, measures, and schemes in the various operations, methods, and processes discussed in the present invention may be interchanged, modified, combined, or deleted. Furthermore, other steps, measures, and schemes in the various operations, methods, and processes discussed in the present invention may also be interchanged, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and schemes in the prior art that are similar to those disclosed in the present invention may also be interchanged, modified, rearranged, decomposed, combined, or deleted.

[0044] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0045] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0046] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0047] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photomask, characterized in that: include: A graphic definition area, wherein the graphic definition area is used to define the pixel opening area of ​​the metal mask, the graphic definition area is a closed figure consisting of four concave arcs and rounded corners connecting the concave arcs, the pixel opening area is a rounded rectangle, the graphic definition area coincides with the center of the pixel opening area, and the area of ​​the graphic definition area is smaller than the area of ​​the pixel opening area.

2. The photomask according to claim 1, wherein: The length of the short side of the graphic definition area is taken as the first critical dimension, and the distance between the midpoint of the arc of the rounded corner of the graphic definition area and the midpoint of the arc of the rounded corner of the pixel opening area is taken as the first distance. When the first critical dimension is greater than or equal to 25 microns and less than or equal to 45 microns, the first distance is greater than or equal to one-fifth of the first critical dimension and less than one-half of the first critical dimension; when the first critical dimension is greater than 45 microns and less than or equal to 80 microns, the first distance is greater than or equal to one-eighth of the first critical dimension and less than one-third of the first critical dimension.

3. The photomask according to claim 2, wherein: When the first critical dimension is greater than or equal to 25 microns and less than or equal to 45 microns, the first distance is a first length; when the first critical dimension is greater than 45 microns and less than or equal to 80 microns, the first distance is a second length; the first length is greater than the second length.

4. The photomask according to claim 2, wherein: The fillet radius of the graphic definition area is the difference between the fillet radius of the pixel opening area and the first distance.

5. The photomask according to claim 4, wherein: The arc length of the rounded corner of the graphic definition area is one quarter of the circle.

6. The photomask according to claim 2, wherein: The distance between the midpoint of the concave arc and the midpoint of the line connecting the endpoints of two adjacent rounded corners is the second distance, and the length of the edge of the pixel opening area corresponding to the concave arc is the second critical dimension. The second distance increases logarithmically with the second critical dimension.

7. The photomask according to claim 6, wherein: When the second critical dimension is greater than or equal to 25 microns and less than or equal to 40 microns, the second distance is the first recess depth; When the second critical dimension is greater than or equal to 40 microns and less than or equal to 50 microns, the second distance is a second recess depth; When the second critical dimension is greater than or equal to 50 micrometers and less than or equal to 80 micrometers, the second distance is a third recess depth.

8. The photomask according to claim 7, wherein: The first recessed depth is smaller than the second recessed depth and smaller than the third recessed depth.

9. A metal mask, characterized in that: The method is prepared using the photomask according to any one of claims 1 to 8.

10. A method for preparing a metal mask, characterized in that: The metal mask is prepared using the photomask according to any one of claims 1 to 8, and is subsequently etched using a wet etching process.

Images