A corner mask plate and a preparation method thereof

Abstract

This invention relates to the field of photomask fabrication technology, and discloses a beveled photomask and its fabrication method, comprising the following steps: sequentially fabricating a conductive film, a solid photoresist film, and a first photoresist film on a transparent substrate; photolithographically forming a first beveled photoresist film pattern on the first photoresist film; electroforming a first beveled electroformed film; fabricating a second photoresist film on the first beveled photoresist film pattern and the first beveled electroformed film; photolithographically forming a second beveled photoresist film pattern on the second photoresist film; electroforming a second beveled electroformed film on the first beveled electroformed film; binding the formed beveled electroformed film assembly to a photomask frame; and finally demolding to form a beveled photomask. This invention allows for sufficiently thin photomasks through electroforming, and simultaneously sets bevels for the holes in the photomask through two electroforming processes. This method can produce photomasks with thinner thickness and higher bevel accuracy for the holes. Such photomasks facilitate uniform filling of organic films within the substrate pixels, thereby improving pixel fill rate and material utilization.

Description

Technical Field

[0001] This invention relates to the field of mask manufacturing technology, and in particular to a chamfered mask and its preparation method. Background Technology

[0002] OLED displays have many advantages over LCD displays, such as better color reproduction, shorter response time, better low-temperature performance, and can be made thinner, lighter, and more flexible. Therefore, OLED displays are replacing LCD displays, which have already established a huge market share, due to their superior performance.

[0003] In OLED display manufacturing, an evaporation deposition machine is used to deposit RGB light-emitting organic materials onto the RGB pixels of the substrate. An evaporation chamber contains a precision mask (FMM) that shields other pixels during deposition. According to the cosine law of evaporation, a portion of the organic material vapor deposits onto the substrate at a certain evaporation incident angle. To ensure uniform filling of the organic film within the substrate pixels and improve material utilization, the holes in the mask pixels are often chamfered. Etching masks use a wet double-sided etching process to create chamfers on both sides of the mask to address this issue. However, higher resolutions require thinner masks, making the etching method inadequate and increasing the difficulty of creating chamfered holes, thus compromising accuracy.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a chamfered mask and its preparation method, which aims to solve the problem that the existing technology cannot guarantee the chamfer accuracy of the mask hole when preparing high-resolution mask.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a chamfered mask, comprising the following steps:

[0008] Conductive films are prepared on transparent substrates;

[0009] A solid photoresist film is prepared on the conductive film;

[0010] A first photoresist film is prepared on the solid photoresist film;

[0011] The first photoresist film is subjected to photolithography to form a first guide-angle photoresist film pattern;

[0012] A first electroforming process is performed on the solid photoresist film to obtain a first guide-angle electroformed film that is complementary to the pattern of the first guide-angle photoresist film.

[0013] A second photoresist film is prepared on the first guide-angle photoresist film pattern and the first guide-angle electroformed film;

[0014] The second photoresist film is subjected to photolithography to form a second guide-angle photoresist film pattern;

[0015] A second electroforming process is performed on the first guide-angle electroformed film to obtain a second guide-angle electroformed film that is complementary to the pattern of the second guide-angle photoresist film. The second guide-angle electroformed film and the first guide-angle electroformed film form a guide-angle electroformed film assembly.

[0016] The beveled electroformed film assembly is bound to the mask frame to form a mask plate;

[0017] The transparent carrier plate, conductive film, and mask plate are peeled off, and photoresist foreign matter on the mask plate is cleaned to obtain a beveled mask plate.

[0018] In the method for preparing the chamfered mask, the angle α between the chamfered side of the hole formed by the first chamfered electroformed film and the plane of the transparent carrier plate is less than 90°.

[0019] In the method for preparing the beveled mask, the angle β between the beveled side of the hole formed by the second beveled electroformed film and the transparent carrier plate is greater than 90°.

[0020] In the method for preparing the chamfered mask, the center line of the hole formed by the first chamfered electroformed film coincides with the center line of the hole formed by the second chamfered electroformed film.

[0021] The method for preparing the chamfered mask plate, after the second electroforming process, further includes the following step:

[0022] An angle-reinforcing rib is then prepared on the second angle-reinforcing electroformed film using an electroforming method.

[0023] The method for preparing the beveled mask involves irradiating the surface of the transparent carrier plate away from the mask plate with a laser to initially separate the mask plate from the conductive film and the transparent carrier plate; and then separating the mask plate from the conductive film and the transparent carrier plate through a demolding process to obtain the beveled mask plate.

[0024] The method for preparing the chamfered mask plate, wherein the demolding process is a mechanical peeling process or an ultrasonic peeling process.

[0025] The method for preparing the beveled mask plate, wherein the first beveled electroformed film and the second beveled electroformed film are made of different materials.

[0026] In the method for preparing the beveled mask, the thicknesses of the first and second photoresist films are independently selected to be 1-20 μm.

[0027] A chamfered mask, wherein the chamfered mask is prepared by the method described in this invention.

[0028] Beneficial effects: This invention uses electroforming to make the mask plate thin enough, and at the same time, it sets the bevel angles of the holes in the mask plate by electroforming twice. The two bevel angles are different from the angle of the transparent carrier plate. This invention can produce a mask plate with thinner thickness and higher bevel angle accuracy of the holes. This mask plate helps to uniformly fill the organic film in the substrate pixels, thereby improving the pixel filling rate and material utilization rate. Attached Figure Description

[0029] Figure 1 A flowchart illustrating a method for preparing a chamfered mask provided by the present invention.

[0030] Figure 2 This is a schematic diagram illustrating the fabrication of the chamfered mask plate in Embodiment 1 of the present invention.

[0031] Figure 3 This is a diagram showing the usage state of the chamfered mask plate prepared in Embodiment 1 of the present invention during vapor deposition and the vapor deposition substrate.

[0032] Figure 4 This is a schematic diagram of the preparation of the chamfered mask plate in Embodiment 2 of the present invention.

[0033] Figure 5 This is a diagram showing the usage state of the beveled mask plate and the vapor deposition substrate during vapor deposition, as obtained in Embodiment 2 of the present invention.

[0034] Figure 6 This is a schematic diagram illustrating the fabrication of the chamfered mask plate in Embodiment 3 of the present invention.

[0035] Figure 7 This is a diagram showing the usage state of the beveled mask plate prepared in Embodiment 3 of the present invention during vapor deposition and the vapor deposition substrate.

[0036] Figure 8 This is a schematic diagram illustrating the fabrication of the chamfered mask plate in Embodiment 4 of the present invention.

[0037] Figure 9 This is a diagram showing the usage state of the chamfered mask plate prepared in Embodiment 4 of the present invention during vapor deposition and the vapor deposition substrate. Detailed Implementation

[0038] This invention provides a chamfered mask and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention.

[0039] Please see Figure 1 , Figure 1A flowchart of a method for fabricating a chamfered mask provided by the present invention is shown in the figure, which includes the following steps:

[0040] S10. Prepare a conductive film on a transparent substrate;

[0041] S20. Prepare a solid photoresist film on the conductive film;

[0042] S30. A first photoresist film is prepared on the solid photoresist film;

[0043] S40. Perform photolithography on the first photoresist film to form a first guide-angle photoresist film pattern;

[0044] S50. Perform a first electroforming process on the solid photoresist film to obtain a first guide-angle electroformed film that is complementary to the pattern of the first guide-angle photoresist film.

[0045] S60. A second photoresist film is prepared on the first guide-angle photoresist film pattern and the first guide-angle electroformed film;

[0046] S70. The second photoresist film is subjected to photolithography to form a second guide-angle photoresist film pattern.

[0047] S80. A second electroforming process is performed on the first guide angle electroformed film to obtain a second guide angle electroformed film that is complementary to the pattern of the second guide angle photoresist film. The second guide angle electroformed film and the first guide angle electroformed film form a guide angle electroformed film assembly.

[0048] S90. The beveled electroformed film assembly is bound to the mask frame to form a mask plate;

[0049] S100: Peel off the transparent carrier plate, conductive film and mask plate, and clean the photoresist foreign matter on the mask plate to obtain the beveled mask plate.

[0050] Specifically, such as Figure 2 As shown, a conductive film 20 is first prepared on a transparent substrate 10. The conductive film 20 facilitates photoresist adhesion. For example, the material of the conductive film is one or more of molybdenum oxide, titanium oxide, copper oxide, tin oxide, indium oxide, gallium oxide, iron oxide, zinc oxide, and aluminum oxide, but is not limited to these.

[0051] Next, a solid photoresist film 30 is fabricated on the conductive film 20, and then a first photoresist film 40 is fabricated on the solid photoresist film 30. The first photoresist film 40 is subjected to photolithography to obtain a first beveled photoresist film pattern 50. Then, a first electroforming process is performed on the solid photoresist film 30 to obtain a first beveled electroformed film 60 that is complementary to the first beveled photoresist film pattern 50, such as... Figure 3As shown, the angle α between the beveled side of the aperture formed by the first beveled electroformed film 60 and the plane of the transparent substrate is less than 90°, for example, 30-60°; then, a second photoresist film 70 is prepared on the first beveled photoresist film pattern 50 and the first beveled electroformed film 60, and the second photoresist film 70 is photolithographically processed to form a second beveled photoresist film pattern 80. A second electroforming process is performed on the first beveled electroformed film 60 to obtain a second beveled electroformed film 90 that is complementary to the second beveled photoresist film pattern 80. The second beveled electroformed film 90 and the first beveled electroformed film 60 form a beveled electroformed film assembly, wherein the angle β between the beveled side of the aperture formed by the second beveled electroformed film 90 and the transparent substrate is greater than 90°, for example, 120°-150° (e.g., ...). Figure 3 As shown in the figure, the center line of the hole formed by the first beveled electroformed film coincides with the center line of the hole formed by the second beveled electroformed film; the beveled electroformed film assembly is bound to the mask frame 100 by laser welding to form a mask plate; finally, the transparent carrier plate, conductive film and mask plate are peeled off, and the photoresist foreign matter on the mask plate is cleaned to obtain the beveled mask plate.

[0052] This invention uses electroforming to make the mask plate thin enough, and simultaneously sets the bevel angles of the holes in the mask plate through two electroforming processes. The two bevel angles are different from the angle of the transparent carrier plate. This invention can produce a mask plate with thinner thickness and higher bevel angle accuracy of the holes. This mask plate helps to uniformly fill the organic film in the substrate pixels, thereby improving the pixel fill rate and material utilization.

[0053] In some embodiments, the materials of the first and second beveled electroformed films may be the same or different; the thicknesses of the first and second photoresist films may be independently selected from 1 to 20 μm, but are not limited thereto.

[0054] In some embodiments, a laser is used to irradiate the surface of the transparent carrier plate opposite to the photomask, so as to initially separate the photomask from the conductive film and the transparent carrier plate; through a demolding process, the photomask is separated from the conductive film and the transparent carrier plate to obtain the beveled photomask. In this embodiment, the initial separation of the photomask from the photoresist layer and the transparent carrier plate can be achieved by adding a laser irradiation step, which can shorten the time of the subsequent demolding process and thus improve the production efficiency of the photomask; since the laser irradiation is a non-contact separation process, the force of the laser on the electroformed layer is much smaller than the force on the electroformed layer during mechanical peeling in the prior art, thereby avoiding mechanical damage to the photomask during the initial separation process and thus improving the yield of the photomask. The demolding process in this embodiment is a mechanical peeling process or an ultrasonic peeling process, but is not limited to these.

[0055] In some embodiments, a chamfered mask is also provided, which is prepared using the chamfered mask preparation method described in this invention.

[0056] The present invention will be further explained and illustrated below through specific embodiments:

[0057] Example 1

[0058] A method for preparing a chamfered mask, comprising the following steps:

[0059] like Figure 2-3 As shown, a conductive film 20 is prepared on a transparent substrate 10; then a solid photoresist film 30 is prepared on the conductive film 20, followed by a first photoresist film 40. The first photoresist film 40 is then photolithographically processed to obtain a first guide-angle photoresist film pattern 50; then a first electroforming process is performed on the solid photoresist film 30 to obtain a first guide-angle electroformed film 60 complementary to the first guide-angle photoresist film pattern 50, wherein the angle α between the guide-angle side of the aperture formed by the first guide-angle electroformed film 60 and the plane of the transparent substrate is 60°; next, a second photoresist film 70 is prepared on the first guide-angle photoresist film pattern 50 and the first guide-angle electroformed film 60, and the second photoresist film 70 is photolithographically processed to form a second guide-angle photoresist film pattern 80. A second electroforming process is performed on the film 60 to obtain a second guide-angle electroformed film 90 that is complementary to the second guide-angle photoresist film pattern 80. The second guide-angle electroformed film 90 and the first guide-angle electroformed film 60 form a guide-angle electroformed film assembly. The second guide-angle electroformed film and the first guide-angle electroformed film are made of the same material. The angle β between the guide-angle side of the hole formed by the second guide-angle electroformed film 90 and the transparent carrier plate is 120°, and the center line of the hole formed by the first guide-angle electroformed film coincides with the center line of the hole formed by the second guide-angle electroformed film. The guide-angle electroformed film assembly is bound to the mask frame 100 by laser welding to form a mask plate. Finally, the transparent carrier plate, the conductive film and the mask plate are peeled off, and the photoresist foreign matter on the mask plate is cleaned to obtain the guide-angle mask plate.

[0060] In this embodiment, the second beveled electroformed film is made of the same material as the first beveled electroformed film. Since the two electroformed films in this embodiment are formed by electroforming separately, it is easier to electroform the designed beveled shape than by electroforming once, thereby obtaining a mask with a thinner thickness and higher beveled accuracy of the holes. This mask helps to uniformly fill the organic film in the substrate pixels, thereby improving the pixel fill rate and material utilization.

[0061] Example 2

[0062] A method for preparing a chamfered mask, comprising the following steps:

[0063] like Figure 4-5As shown, a conductive film 20 is prepared on a transparent substrate 10; then a solid photoresist film 30 is prepared on the conductive film 20, and a first photoresist film 40 is prepared on the solid photoresist film 30. The first photoresist film 40 is photolithographically processed to obtain a first guide-angle photoresist film pattern 50; then a first electroforming process is performed on the solid photoresist film 30 to obtain a first guide-angle electroformed film 60 complementary to the first guide-angle photoresist film pattern 50, wherein the angle α between the guide-angle side of the hole formed by the first guide-angle electroformed film 60 and the plane of the transparent substrate is 45°; then a second photoresist film 70 is prepared on the first guide-angle photoresist film pattern 50 and the first guide-angle electroformed film 60, and the second photoresist film 70 is photolithographically processed to form a second guide-angle photoresist film pattern 80. A second electroforming process is performed on the first guide angle photoresist film 60 to obtain a second guide angle electroformed film 90 that is complementary to the second guide angle photoresist film pattern 80. The second guide angle electroformed film 90 and the first guide angle electroformed film 60 form a guide angle electroformed film assembly. The materials of the second guide angle electroformed film and the first guide angle electroformed film are different. The angle β between the guide angle side of the hole formed by the second guide angle electroformed film 90 and the transparent carrier plate is 135°, and the center line of the hole formed by the first guide angle electroformed film coincides with the center line of the hole formed by the second guide angle electroformed film. The guide angle electroformed film assembly is bound to the mask frame 100 by laser welding to form a mask plate. Finally, the transparent carrier plate, conductive film and mask plate are peeled off, and photoresist foreign matter on the mask plate is cleaned to obtain the guide angle mask plate.

[0064] In this embodiment, the second beveled electroformed film is made of a different material than the first beveled electroformed film. Preferably, the first beveled electroformed film is made of a material that is not easily scratched by the substrate, such as copper; the second beveled electroformed film is made of a soft magnetic material, such as a nickel-iron alloy. Since the mask in this embodiment is formed by two electroforming processes, mask panels made of different materials can be produced, whereas a single electroforming process can only produce mask panels made of the same material. Furthermore, the two-stage electroforming method makes it easier to electroform the designed bevel shape, resulting in a thinner mask with higher bevel accuracy. This mask helps to uniformly fill the organic film within the substrate pixels, thereby improving pixel fill rate and material utilization.

[0065] Example 3

[0066] A method for preparing a chamfered mask, comprising the following steps:

[0067] like Figure 6-7As shown, a conductive film 20 is prepared on a transparent substrate 10; then a solid photoresist film 30 is prepared on the conductive film 20, and a first photoresist film 40 is prepared on the solid photoresist film 30. The first photoresist film 40 is photolithographically processed to obtain a first guide-angle photoresist film pattern 50; then a first electroforming process is performed on the solid photoresist film 30 to obtain a first guide-angle electroformed film 60 complementary to the first guide-angle photoresist film pattern 50, wherein the angle α between the guide-angle side of the hole formed by the first guide-angle electroformed film 60 and the plane of the transparent substrate is 120°; then a second photoresist film 70 is prepared on the first guide-angle photoresist film pattern 50 and the first guide-angle electroformed film 60, and the second photoresist film 70 is photolithographically processed to form a second guide-angle photoresist film pattern 80. A second electroforming process is performed on the first guide angle photoresist film 60 to obtain a guide angle reinforcing rib 90 that is complementary to the second guide angle photoresist film pattern 80. The guide angle reinforcing rib 90 and the first guide angle electroformed film 60 form a guide angle electroformed film assembly. The guide angle reinforcing rib and the first guide angle electroformed film may be made of the same or different materials. The angle β between the guide angle side of the hole formed by the guide angle reinforcing rib 90 and the transparent carrier plate is 135°, which is greater than the angle α. The center line of the hole formed by the first guide angle electroformed film coincides with the center line of the hole formed by the guide angle reinforcing rib. The guide angle electroformed film assembly is bound to the mask frame 100 by laser welding to form a mask plate. Finally, the transparent carrier plate, conductive film and mask plate are peeled off, and photoresist foreign matter on the mask plate is cleaned to obtain the guide angle mask plate.

[0068] In this embodiment, the first beveled electroformed film and the beveled reinforcing rib film are formed separately by electroforming in two stages, and the beveled reinforcing rib film can be strengthened by the first beveled electroformed film. Therefore, the first beveled electroformed film can be made very fine to obtain higher resolution. This mask helps to uniformly fill the organic film in the substrate pixel, thereby improving the pixel fill rate and material utilization.

[0069] Example 4

[0070] A method for preparing a chamfered mask, comprising the following steps:

[0071] like Figure 8-9As shown, a conductive film 20 is prepared on a transparent substrate 10; then a solid photoresist film 30 is prepared on the conductive film 20, followed by the preparation of a first photoresist film 40 on the solid photoresist film 30. The first photoresist film 40 is then photolithographically processed to obtain a first guide-angle photoresist film pattern 50; next, a first electroforming process is performed on the solid photoresist film 30 to obtain a first guide-angle electroformed film 60 complementary to the first guide-angle photoresist film pattern 50, wherein the angle α between the guide-angle side of the aperture formed by the first guide-angle electroformed film 60 and the plane of the transparent substrate is 60°; then, a second photoresist film is prepared on the first guide-angle photoresist film pattern 50 and the first guide-angle electroformed film 60. The second photoresist undergoes photolithography to form a second bevel photoresist film pattern 70. A second electroforming process is then performed on the first bevel electroformed film 60 to obtain a second bevel electroformed film 80 that is complementary to the second bevel photoresist film pattern 70. The second bevel electroformed film 80 and the first bevel electroformed film 60 form a bevel electroformed film assembly. The second bevel electroformed film and the first bevel electroformed film are made of the same material. The bevel side of the hole formed by the second bevel electroformed film 80 has an angle β of 120° with the transparent substrate, and the center line of the hole formed by the first bevel electroformed film coincides with the center line of the hole formed by the second bevel electroformed film.

[0072] Next, a third photoresist film is prepared on the second guide-angle photoresist film pattern 70 and the second guide-angle electroformed film 80. The third photoresist film is then photolithographically processed to form a third guide-angle photoresist film pattern 90. A third electroforming process is then performed on the second guide-angle electroformed film 80 to obtain a guide-angle reinforcing rib 100 complementary to the third guide-angle photoresist film pattern 90. The angle γ between the guide-angle side of the aperture formed by the guide-angle reinforcing rib 100 and the transparent substrate is 135°, which is greater than the angle β. The guide-angle reinforcing rib 100 forms... The center line of the hole coincides with the center line of the hole formed by the second beveled electroformed film. The beveled reinforcing rib is made of the same material as the second beveled electroformed film. The beveled reinforcing rib 100, the second beveled electroformed film 80, and the first beveled electroformed film 60 form a beveled electroformed film assembly. The beveled electroformed film assembly is bound to the mask frame 110 by laser welding to form a mask plate. Finally, the transparent carrier plate, the conductive film, and the mask plate are peeled off, and the photoresist foreign matter on the mask plate is cleaned to obtain the beveled mask plate.

[0073] The bevel mask in this embodiment is made by three electroforming processes. Since the first bevel electroformed film and the bevel reinforcing rib are formed by two separate electroforming processes, and the bevel reinforcing rib can strengthen the bevel electroformed film, the bevel electroformed film can be made very fine to obtain higher resolution. This mask helps to uniformly fill the organic film in the substrate pixel, thereby improving the pixel fill rate and material utilization.

[0074] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a chamfered mask, characterized in that, Including the following steps: Conductive films are prepared on transparent substrates; A solid photoresist film is prepared on the conductive film; A first photoresist film is prepared on the solid photoresist film; The first photoresist film is subjected to photolithography to form a first guide-angle photoresist film pattern; A first electroforming process is performed on the solid photoresist film to obtain a first guide-angle electroformed film that is complementary to the pattern of the first guide-angle photoresist film. The angle α between the guide-angle side of the hole formed by the first guide-angle electroformed film and the plane of the transparent carrier plate is 30°-60°. A second photoresist film is prepared on the first guide-angle photoresist film pattern and the first guide-angle electroformed film; The second photoresist film is subjected to photolithography to form a second guide-angle photoresist film pattern; A second electroforming process is performed on the first beveled electroformed film to obtain a second beveled electroformed film that is complementary to the pattern of the second beveled photoresist film. The angle β between the beveled side of the hole formed by the second beveled electroformed film and the transparent carrier plate is 120°-150°. The second beveled electroformed film and the first beveled electroformed film form a beveled electroformed film assembly. The center line of the hole formed by the first beveled electroformed film coincides with the center line of the hole formed by the second beveled electroformed film. The beveled electroformed film assembly is bound to the mask frame to form a mask plate; The process of peeling off the transparent carrier plate, conductive film, and mask plate specifically includes: irradiating the surface of the transparent carrier plate away from the mask plate with a laser to initially separate the mask plate from the conductive film and the transparent carrier plate; and separating the mask plate from the conductive film and the transparent carrier plate through a mechanical peeling process or an ultrasonic peeling process. After cleaning the photoresist foreign matter off the photomask, a beveled photomask is obtained. The thickness of the first photoresist film and the second photoresist film are independently selected to be 1-20 μm. The materials of the first beveled electroformed film and the second beveled electroformed film are different.

2. The method for preparing the chamfered mask according to claim 1, characterized in that, After the second electroforming process, the following steps are also included: An angle-reinforcing rib is then prepared on the second angle-reinforcing electroformed film using an electroforming method.

3. A chamfered mask, characterized in that, It is prepared by the method described in any one of claims 1-2.

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