Preparation method of mask plate and mask plate

Abstract

The invention discloses a preparation method of a mask plate and the mask plate, and relates to the technical field of masks.The preparation method of the mask plate comprises the following steps that a silicon-based substrate is provided; forming a plurality of convex microstructures on the first surface of the silicon-based substrate outside the evaporation opening area; forming a metal mask covering the convex microstructures on the silicon-based substrate; and etching the silicon-based substrate to form an evaporation opening in a preset evaporation opening area of the silicon-based substrate. The contact area between the metal mask and the silicon-based substrate is increased through the convex microstructures, on one hand, more contact points can be provided, the total amount of physical attraction force between the metal mask and the silicon-based substrate is increased, so that the adhesive force is improved, on the other hand, the stress of the contact surface between the metal mask and the silicon-based substrate can be dispersed between the convex microstructures, and the contact area between the metal mask and the silicon-based substrate is increased. Local stress concentration is reduced, so that the metal mask is prevented from falling off from the silicon-based substrate, and the adhesive force and adhesive force between the metal mask and the silicon-based substrate are improved.

Description

Technical Field

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

[0002] Organic Light Emitting Diode (OLED) display technology is widely used in mobile phones, televisions, cars and other fields due to its many advantages such as self-luminescence, wide color gamut and flexible display.

[0003] In special application scenarios such as VR and AR technology, the display screen needs to have higher resolution and smaller size. In order to achieve high resolution, the existing micro-OLED technology uses white light OLED with color filter technology to achieve color display. This technology can avoid the use of FMM (Fine metal mask) in the OLED evaporation stage, and achieve color display through photolithography patterning of RGB three-color filters; however, the color filter will lose about 60% of the brightness of the sub-pixel, and the existing white light OLED device uses a tandem (double stack) structure, which increases the operating voltage and power consumption of the device, and increases the design requirements for the driver chip. At the same time, due to the use of a metal charge generation layer in the tandem device, the lateral leakage phenomenon will be aggravated.

[0004] Therefore, in order to avoid the brightness loss, increased operating voltage and power consumption, and increased leakage problems caused by the above technologies, the technology of using FMM to directly deposit the RGB light-emitting layer will be one of the main technical routes for micro-OLED to achieve high brightness.

[0005] Traditional FMMs are made of invar alloy. However, the chemical compatibility between invar alloy and silicon wafer substrate is poor. Strong chemical bonds cannot be formed between the two, and the interface interaction is weak, resulting in insufficient adhesion between invar alloy and silicon wafer substrate. Summary of the invention

[0006] The main purpose of the present invention is to provide a mask and a method for preparing the mask, aiming to solve the problem of insufficient adhesion between the invar alloy of the traditional FMM and the silicon wafer substrate.

[0007] To achieve the above object, the present invention provides a method for preparing a mask, comprising the following steps:

[0008] Providing a silicon-based substrate; wherein the silicon-based substrate is preset with a plurality of evaporation opening areas;

[0009] forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area;

[0010] forming a metal mask covering the protruding microstructure on the silicon-based substrate;

[0011] The silicon-based substrate is etched to form an evaporation opening in the evaporation opening area preset on the silicon-based substrate.

[0012] In one embodiment, the step of forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area includes:

[0013] Depositing a first dielectric layer on the first surface of the silicon-based substrate;

[0014] The first dielectric layer is patterned to form a plurality of protruding microstructures outside the evaporation opening area.

[0015] In one embodiment, after the step of forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area, the method further includes:

[0016] An adhesion promoting layer is formed to cover the surface of the protruding microstructure and a surface of a portion of the silicon-based substrate that is not in the evaporation opening area; the adhesion promoting layer has an uneven surface.

[0017] In one embodiment, the step of forming a metal mask covering the protruding microstructure on the silicon-based substrate comprises:

[0018] forming a metal layer on the silicon-based substrate, wherein the metal layer covers the protruding microstructure;

[0019] forming a first patterned photoresist on the metal layer;

[0020] The area of ​​the metal layer not covered by the first patterned photoresist is etched to form the metal mask, wherein the metal mask includes metal sub-masks corresponding to the plurality of preset evaporation opening areas, and each of the metal sub-masks has a plurality of pixel openings arranged in an array.

[0021] In one embodiment, before the step of forming a metal mask covering the protruding microstructure on the silicon-based substrate, the method further includes:

[0022] Forming a seed layer on the surface of the adhesion promoting layer on the silicon-based substrate, wherein the seed layer covers the protruding microstructure and the adhesion promoting layer, and the seed layer has a flat surface;

[0023] The step of forming a metal mask covering the protruding microstructure on the silicon-based substrate comprises:

[0024] forming a second patterned photoresist on the seed layer;

[0025] Using an electroforming process to form a metal structure in the area on the seed layer that is not covered by the second patterned photoresist, to obtain the metal mask, wherein the metal mask includes metal sub-masks corresponding to the plurality of preset evaporation opening areas, each of the metal sub-masks having a plurality of pixel openings arranged in an array;

[0026] After the step of etching the silicon-based substrate to form an evaporation opening in the evaporation opening area preset on the silicon-based substrate, the method further includes:

[0027] The seed layer is patterned so that each pixel opening is connected to the corresponding evaporation opening.

[0028] In one embodiment, the step of patterning the seed layer so that each of the pixel openings is connected to the corresponding evaporation opening comprises:

[0029] Forming a third patterned photoresist on the metal structure, wherein the third patterned photoresist covers the surface area of ​​the metal structure except the pixel opening;

[0030] The seed layer is etched using the third patterned photoresist and the metal structure as masks, and through holes connected to the evaporation openings are formed on the seed layer corresponding to each pixel opening, so as to connect each pixel opening to the corresponding evaporation opening.

[0031] In one embodiment, the step of etching the silicon-based substrate to form an evaporation opening in the evaporation opening area preset in the silicon-based substrate includes:

[0032] A photoresist formed on a second surface of the silicon-based substrate, wherein the second surface and the first surface are located on two opposite sides of the silicon-based substrate;

[0033] Patterning the photoresist on the second surface to expose each of the evaporation opening areas;

[0034] The silicon-based substrate at each of the evaporation opening regions is etched to form a plurality of the evaporation openings.

[0035] The present invention also provides a mask, comprising:

[0036] A silicon-based substrate, wherein a plurality of evaporation openings penetrating the silicon-based substrate are formed on the silicon-based substrate, and a convex microstructure is arranged in an area of ​​the first surface of the silicon-based substrate except for the evaporation openings;

[0037] A metal mask, wherein the metal mask includes a metal structure and a seed layer, wherein the seed layer is covered on top of the raised microstructure, the metal structure is correspondingly arranged above the seed layer, and a plurality of connected pixel openings are opened on the metal main layer corresponding to each of the vapor deposition openings, and a through hole is formed at each of the pixel openings corresponding to the seed layer to connect the pixel opening with the corresponding vapor deposition opening.

[0038] In one embodiment, an adhesion promoting layer is further provided between the seed layer and the raised microstructure, and the adhesion promoting layer covers the surface of the raised microstructure and the surface of part of the silicon-based substrate other than the evaporation opening area; the adhesion promoting layer has an uneven surface.

[0039] In one embodiment, the protruding microstructure is a plurality of strip structures extending along a first direction and spaced apart along a second direction; or, the protruding microstructure is a plurality of strip structures extending along a second direction and spaced apart along the first direction, wherein the first direction is perpendicular to the second direction; and / or,

[0040] The protruding microstructures are a plurality of independently arranged island structures, and the protruding microstructures are formed on the first surface of the silicon-based substrate outside the evaporation opening area.

[0041] In one embodiment, a plurality of the evaporation opening arrays are arranged on the silicon-based substrate.

[0042] The technical solution of the present invention prepares a raised microstructure on a silicon-based substrate, and increases the contact area between the metal mask and the silicon-based substrate through the raised microstructure. On the one hand, more contact points can be provided, increasing the total amount of physical attraction between the metal mask and the silicon-based substrate, thereby improving adhesion. On the other hand, the stress on the contact surface of the two can be dispersed between the raised microstructures, reducing local stress concentration, thereby preventing the metal mask from falling off the silicon-based substrate and improving the bonding and adhesion between the metal mask and the silicon-based substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0044] Figure 1 A flowchart of a method for preparing a mask provided by the present invention;

[0045] Figure 2A detailed flowchart of step S200 of the method for preparing a mask provided by the present invention;

[0046] Figure 3 A detailed flowchart of step S300 of an embodiment of a method for preparing a mask provided by the present invention;

[0047] Figure 4 A detailed flowchart of step S300 of another embodiment of the method for preparing a mask provided by the present invention;

[0048] Figure 5 A detailed flowchart of step S500 of the method for preparing a mask provided by the present invention;

[0049] Figure 6 A detailed flowchart of step S400 of the method for preparing a mask provided by the present invention;

[0050] Figure 7 A schematic diagram of the structure of the mask provided by the present invention;

[0051] Figure 8 A partial structural schematic diagram of a mask provided in one embodiment of the present invention;

[0052] Fig. 9 A partial structural schematic diagram of a mask provided in another embodiment of the present invention;

[0053] Fig.10 A partial structural schematic diagram of a mask provided in yet another embodiment of the present invention;

[0054] Fig.11 A schematic cross-sectional view of a partial structure of a mask provided by the present invention;

[0055] Fig.12 A schematic diagram of a metal sub-mask of a mask provided by the present invention;

[0056] Fig.13 A schematic structural diagram of the mask provided by the present invention corresponding to step S210;

[0057] Fig.14 A schematic structural diagram of the mask provided by the present invention corresponding to step S230;

[0058] Fig.15 A schematic structural diagram of the mask provided by the present invention corresponding to step S290;

[0059] Fig.16 A schematic diagram of the structure of the mask provided by the present invention forming a photoresist on a seed layer;

[0060] Fig.17A schematic structural diagram of the mask provided by the present invention corresponding to step S310b;

[0061] Fig.18 A schematic structural diagram of the mask provided by the present invention corresponding to step S320b;

[0062] Fig.19 A schematic structural diagram of the mask provided by the present invention corresponding to step S410;

[0063] Fig. 20 This is a schematic structural diagram of the mask provided by the present invention corresponding to step S420 and step S510.

[0064] Description of Figure Numbers:

[0065] 100. Mask; 1. Silicon-based substrate; 11. Evaporation opening; 21. Raised microstructure; 22. First dielectric layer; 23. Adhesion-promoting layer; 3. Metal mask; 31. Seed layer; 32. Metal structure; 33. Pixel opening; 40. First photoresist layer; 41. Second photoresist layer; 42. Third photoresist layer; 43. Fourth photoresist layer.

[0066] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0067] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0069] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0070] Traditional FMM is made of invar alloy. A coating material such as photoresist is applied to the invar alloy through the openings of a template using a stretching process to form a desired pattern. The template is then removed and the coating material is processed to form an invar alloy with the desired pattern. Errors will occur during the removal of the template and subsequent processing of the coating material (such as etching, welding, developing, etc.). Due to the limitations of the processing technology, the opening size and resolution of the FMM cannot meet the requirements of microdisplay.

[0071] In order to solve the above problems, the present invention provides a method for preparing a mask.

[0072] Please combine Figure 1 , Figure 7 and Figures 11 to 18 ,in, Fig. 9 for Figure 7 The cross-sectional schematic diagram of the dotted line frame portion along the horizontal dotted line, in one embodiment of the present invention, the method for preparing the mask includes the following steps:

[0073] S100: Providing a silicon-based substrate; wherein the silicon-based substrate is preset with a plurality of evaporation opening areas;

[0074] It can be understood that, according to the size of the silicon-based substrate 1 and the size of the evaporation opening 11 to be prepared, the area of ​​the evaporation opening 11 to be formed on the silicon-based substrate 1 is preset in advance, so as to facilitate subsequent preparation;

[0075] S200: forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area;

[0076] The protruding microstructure 21 is used to increase the contact area between the seed layer 31 and the silicon-based substrate 1, thereby improving the adhesion and connection stability between the seed layer 31 and the silicon-based substrate 1;

[0077] S300: forming a metal mask covering the protruding microstructure on the silicon-based substrate;

[0078] S400: etching the silicon-based substrate to form an evaporation opening in a preset evaporation opening area of ​​the silicon-based substrate.

[0079] The technical solution of the present invention prepares a raised microstructure on a silicon-based substrate, and increases the contact area between the metal mask and the silicon-based substrate through the raised microstructure. On the one hand, more contact points can be provided, increasing the total amount of physical attraction between the metal mask and the silicon-based substrate, thereby improving adhesion. On the other hand, the stress on the contact surface of the two can be dispersed between the raised microstructures, reducing local stress concentration, thereby preventing the metal mask from falling off the silicon-based substrate and improving the adhesion between the metal mask and the silicon-based substrate.

[0080] It can be understood that the material of the substrate can also be common light-shielding substrate materials, such as metals, ceramics and polymers, which can be selected according to actual needs. The commonly used substrate material is usually silicon. Silicon-based substrates have good chemical stability and mechanical strength, are compatible with photolithography processes, and are suitable for high-precision pattern preparation. The cost of silicon is relatively low and the cost performance is high.

[0081] Please combine Figure 2 and Fig.13 In one embodiment, step S200 includes:

[0082] S210: depositing a first dielectric layer on a first surface of the silicon-based substrate;

[0083] Optionally, the material of the first dielectric layer 22 can be SiO2 or SiN x Since the silicon-based substrate 1 is made of Si, SiO2 or SiN is deposited on the silicon-based substrate 1. x Form a first dielectric layer 22, on the one hand, SiO2 and SiN x The SiO2 and SiN substrates have good adhesion and adhesion, which can improve the connection stability between the protruding microstructures 21 and the Si-based substrate 1. x Both can form relatively fine structures, which are convenient for use in high-precision application scenarios;

[0084] Optionally, the first dielectric layer 22 may be formed by deposition using a PECVD (plasma enhanced chemical vapor deposition) process. The first dielectric layer 22 deposited using the PECVD process has a strong adhesion force and can be firmly attached to the surface of the silicon-based substrate 1, thereby improving stability.

[0085] S220: patterning the first dielectric layer to form a plurality of protruding microstructures outside the evaporation opening area.

[0086] The specific process of patterning the first dielectric layer 22 is generally to first coat a layer of photoresist on the first dielectric layer 22 and perform soft baking to cure the photoresist; then, use the mask 100 to align the pre-designed pattern (i.e., the pre-designed pattern of the raised microstructure 21) on the photoresist, and expose it through a light source such as ultraviolet light, deep ultraviolet light or an electron beam, so that the photoresist undergoes a chemical reaction in a specific area; after exposure, the sample is placed in a developer, and the developer will dissolve the exposed area (positive photoresist) or the unexposed area (negative photoresist), thereby revealing the pattern on the photoresist; after development, hard baking is performed to improve the etching resistance of the photoresist; next, the first dielectric layer 22 that is not protected by the photoresist is etched away using an etching process, and the remaining part forms the desired raised microstructure 21. After etching is completed, the photoresist is removed by an organic solvent or plasma treatment to expose the etched raised microstructure 21.

[0087] See also Fig.14 , further, after step S200, it also includes:

[0088] S230: forming an adhesion promoting layer to cover the surface of the protruding microstructure and the surface of a portion of the non-evaporation opening area of ​​the silicon-based substrate; the adhesion promoting layer has an uneven surface.

[0089] The adhesion promoting layer 23 covers the surface of the raised microstructure 21 , so that the adhesion promoting layer 23 forms a serpentine bending structure, thereby greatly increasing the surface area of ​​the adhesion promoting layer 23 , and further increasing the contact area between the adhesion promoting layer 23 and the seed layer 31 , thereby improving the stability of the seed layer 31 .

[0090] Specifically, the material of the adhesion promoting layer 23 can be TiO2, and a strong force similar to an ionic bond can be formed between TiO2 and the subsequently prepared seed layer 31, thereby improving the adhesion between the seed layer 31 and the adhesion promoting layer 23; optionally, the TiO2 layer can be deposited by an ALD (atomic layer deposition) process, and the ALD process has strong step coverage and can completely cover the surface of the protruding microstructure 21, so that the adhesion promoting layer 23 can fully contact the protruding microstructure 21, thereby improving the contact stability.

[0091] See also Figure 3 In one embodiment, step S300 includes:

[0092] S310a: forming a metal layer on the silicon-based substrate, wherein the metal layer covers the protruding microstructure;

[0093] It should be noted that the metal layer can be formed by directly depositing using a relatively mature PVD or CVD process in the prior art;

[0094] S320a: forming a first patterned photoresist on the metal layer;

[0095] The first patterned photoresist covers the metal layer and exposes the position of the metal layer where the pixel opening is to be formed, so as to facilitate subsequent etching of the position to form the pixel opening. The photoresist is used to protect the area of ​​the metal layer other than the pixel opening from being etched;

[0096] S330a: Etching the area of ​​the metal layer not covered by the first patterned photoresist to form a metal mask, wherein the metal mask includes metal sub-masks corresponding to a plurality of preset evaporation opening areas, and each metal sub-mask has a plurality of pixel openings arranged in an array.

[0097] By shielding the metal layer with photoresist, the metal layer is prevented from being damaged in the area other than the pixel opening during the etching process, thereby improving the accuracy of the pixel opening, enhancing the resolution, and ensuring the integrity of the metal mask.

[0098] Please combine Figure 4 and Figures 15 to 18 In another embodiment, before step S300, the process includes:

[0099] S290: forming a seed layer on the surface of the adhesion promoting layer, wherein the seed layer covers the protruding microstructure and the adhesion promoting layer, and the seed layer has a flat surface;

[0100] The seed layer 31 is used to provide support and a conductive path for the metal structure 32 during subsequent electroforming, and the metal structure 32 needs to form pixel openings 33 at the corresponding preset evaporation opening areas. Therefore, the seed layer 31 not only needs to cover the protruding microstructure 21, but also needs to cover the area of ​​the first surface except the protruding microstructure 21. It should be noted that in order to ensure the flatness of the metal structure 32, the upper surface of the seed layer 31 corresponding to the protruding microstructure 21 and the upper surface corresponding to the area of ​​the first surface except the protruding microstructure 21 need to be flush;

[0101] Specifically, the material of the seed layer 31 can be titanium-chromium alloy. When the titanium-chromium alloy is exposed to air or oxygen, an oxide layer will be formed on the surface. These oxide layers can form a strong chemical bond with the adhesion promotion layer 23 formed by TiO2, which enhances the adhesion between the two, thereby improving the connection stability between the seed layer 31 and the silicon-based substrate 1, and further improving the stability between the metal mask 3 and the silicon-based substrate 1, avoiding the metal mask 3 from deviating during use and affecting the accuracy, and improving the accuracy and resolution of the mask 100;

[0102] Optionally, the seed layer 31 may be deposited by a PVD (physical vapor deposition) process, which may enable the seed layer 31 to obtain stronger adhesion, improve the connection stability between the seed layer 31 and the adhesion-promoting layer 23, and enhance the adhesion between the seed layer 31 and the adhesion-promoting layer 23;

[0103] Step S300 includes:

[0104] S310b: forming a second patterned photoresist on the seed layer;

[0105] It should be noted that, for ease of understanding, the second patterned photoresist is named the first photoresist layer 40, corresponding to the reference numerals in the accompanying drawings. It can be understood that a pixel opening 33 needs to be opened on the metal mask 3 at each preset evaporation opening 11 area, and the position of the pixel opening 33 is also preset. Therefore, a second patterned photoresist is formed on the seed layer 31, and the second patterned photoresist blocks the position of each preset pixel opening 33 to expose the area on the seed layer 31 except the position of each preset pixel opening 33;

[0106] S320b: forming a metal structure in an area on the seed layer that is not covered by the second patterned photoresist by an electroforming process to obtain a metal mask, wherein the metal mask includes metal sub-masks corresponding to a plurality of preset evaporation opening areas, and each metal sub-mask has a plurality of pixel openings arranged in an array;

[0107] The metal structure 32 is directly electroformed by an electroforming process. During the electroforming process, the metal structure 32 is not formed in the area where the second patterned photoresist is located due to the shielding of the second patterned photoresist. Therefore, during the electroforming process, the metal structure 32 is not deposited at the area corresponding to the second patterned photoresist, and the pixel opening 33 is directly formed, which helps to improve the accuracy of the pixel opening 33.

[0108] After step S400, the following steps are also included:

[0109] S500: patterning the seed layer so that each pixel opening is connected to a corresponding evaporation opening.

[0110] Each metal sub-mask corresponds to an evaporation opening 11, so that the metal sub-mask corresponding to each evaporation opening 11 has an array-arranged pixel opening 33 connected to the evaporation opening 11. An independent sub-mask plate can be formed at each evaporation opening 11, so that multiple devices or patterns can be manufactured simultaneously during a single evaporation process, thereby significantly improving manufacturing efficiency and reducing production time and cost.

[0111] The metal mask 3 is directly prepared on the silicon-based substrate 1 through an electroplating process, and the pixel openings 33 are directly formed in the preparation process, rather than the traditional method of opening the pixel openings 33 on the complete metal mask 3 through a stretching process. This eliminates the need for stretching process processing and subsequent etching and welding operations, avoids the errors that may be caused to the metal mask 3 by the above operations, and avoids the loss of precision, so that smaller and more precise pixel openings 33 can be formed on the metal mask 3. Smaller size and higher precision mean higher resolution of the mask 100, so that the opening size and resolution of the mask 100 can meet the requirements of micro-display, so that smaller and more precise pixel openings 33 can be formed on the metal mask 3, which greatly reduces the opening size of the metal main layer and improves the resolution of the mask 100.

[0112] Please combine Figure 5 , Fig.11 and Fig. 20 , further, step S500 includes:

[0113] S510: forming a third patterned photoresist on the metal structure, wherein the third patterned photoresist covers the surface area of ​​the metal structure except for the pixel opening;

[0114] It should be noted that, for ease of understanding, the third patterned photoresist is named the second photoresist layer 41 so as to correspond to the reference numerals in the accompanying drawings;

[0115] S520: using the third patterned photoresist and the metal structure as a mask, etching the seed layer, and forming through holes connected to the evaporation openings at locations corresponding to the pixel openings on the seed layer, so as to connect the pixel openings to the corresponding evaporation openings.

[0116] The surface of the metal structure 32 except the pixel opening 33 is completely covered by the third patterned photoresist to avoid damage to the metal structure 32 when etching the seed layer 31, thereby improving the accuracy of the metal structure 32 and the pixel opening 33, and improving the resolution of the mask 100.

[0117] Please combine Figure 6 , Fig.19 and Fig. 20 In one embodiment, step S400 includes:

[0118] S410: forming a photoresist on a second surface of the silicon-based substrate, wherein the second surface and the first surface are located on two opposite sides of the silicon-based substrate;

[0119] A photoresist is coated on a surface of the silicon-based substrate 1 opposite to the metal mask 3, that is, the second surface. For ease of understanding, the photoresist on the second surface is named as a third photoresist layer 42, so as to correspond to the reference numerals in the drawings.

[0120] S420: patterning the photoresist on the second surface to expose each evaporation opening area;

[0121] The photoresist on the second surface is removed at positions corresponding to the regions of the evaporation openings 11, so that the regions of the evaporation openings 11 are exposed;

[0122] S430: etching the silicon-based substrate at each evaporation opening region to form a plurality of evaporation openings.

[0123] The silicon-based substrate 1 in the region of each evaporation opening 11 is etched so that the pixel opening 33 corresponding to each evaporation opening 11 can transmit light, thereby improving the resolution.

[0124] Furthermore, the distance between the side walls of each evaporation opening 11 along the first direction is gradually reduced from bottom to top, and the distance between the side walls of the evaporation opening 11 along the first direction is gradually reduced from bottom to top, which can prevent etching gas and the like from entering the seed layer 31 and causing damage to the seed layer 31, thereby playing a protective role. At the same time, the inclined side wall can make the etching process more uniform and avoid the problem of excessive or insufficient etching caused by the vertical etching side wall.

[0125] In one embodiment, before step S430, the method further includes:

[0126] S429: Laying a photoresist on the metal structure, wherein the photoresist covers the metal structure and fills each pixel opening.

[0127] It should be noted that, for the sake of ease of understanding, the photoresist laid on the metal structure 32 in this step is named the fourth photoresist layer 43, so as to correspond to the numbers in the accompanying drawings. By laying the fourth photoresist layer 43 on the metal structure 32 as a protective layer, the fourth photoresist layer 43 fills each pixel opening 33, thereby completely covering and shielding the metal structure 32, preventing the etching gas from damaging the metal structure 32 when the silicon-based substrate 1 is subsequently etched, thereby affecting the accuracy of the metal structure 32 and the pixel opening 33.

[0128] Please combine Figure 7 , Fig.11 and Fig.12The present invention further proposes a mask plate 100, which is made by the above-mentioned mask plate 100 preparation method. The mask plate 100 includes a silicon-based substrate 1 and a metal mask 3. A plurality of evaporation openings 11 penetrating the silicon-based substrate 1 are formed on the silicon-based substrate 1, and a protruding microstructure 21 is arranged on the first surface of the silicon-based substrate 1 except for the evaporation openings 11; the metal mask 3 includes a metal structure 32 and a seed layer 31, the seed layer 31 is covered on the protruding microstructure 21, the metal structure 32 is correspondingly arranged on the seed layer 31, and a plurality of connected pixel openings 33 are opened on the metal main layer corresponding to each evaporation opening 11, and a through hole connecting the pixel opening 33 with the corresponding evaporation opening 11 is formed at the seed layer 31 corresponding to each pixel opening 33.

[0129] A layer of raised microstructure 21 is arranged between the silicon-based substrate 1 and the seed layer 31 of the present invention, which increases the contact area between the seed layer 31 and the silicon-based substrate 1, thereby increasing the adhesion between the seed layer 31 and the silicon-based substrate 1, and further increasing the stability of the seed layer 31. The seed layer 31 provides a conductive path for preparing the metal structure 32, and can also help the metal structure 32 to be electroformed uniformly, thereby improving the uniformity of the metal structure 32 and reducing defects, thereby improving the accuracy of the pixel opening 33 formed after the metal structure 32 is electroformed, and further increasing the resolution of the mask 100.

[0130] In one embodiment, an adhesion promoting layer 23 is further provided between the seed layer 31 and the raised microstructure 21, and the adhesion promoting layer 23 covers the surface of the raised microstructure 21 and the surface of a portion of the silicon-based substrate 1 in the non-evaporated opening 11 area; the adhesion promoting layer 23 has an uneven surface.

[0131] The adhesion promoting layer 23 has an uneven surface, thereby increasing its contact area with the seed layer 31 and improving the connection stability between the adhesion promoting layer 23 and the seed layer 31. At the same time, the adhesion promoting layer 23 can form a strong force similar to an ionic bond with the seed layer 31, thereby increasing the adhesion between the seed layer 31 and the adhesion promoting layer 23, and further improving the connection stability between the seed layer 31 and the silicon-based substrate 1.

[0132] See also Figure 8 In one embodiment, the protruding microstructures 21 are a plurality of strip-shaped structures extending along the first direction and spaced apart along the second direction;

[0133] See also Fig. 9 In another embodiment, the protruding microstructure 21 is a plurality of strip structures extending along the second direction and spaced apart along the first direction, wherein the first direction is perpendicular to the second direction.

[0134] It should be noted that the first direction is Figure 7 and Figure 8The X direction in the second direction is Figure 7 and Figure 8 in the Y direction.

[0135] The main function of the raised microstructure 21 is to increase the contact area between the seed layer 31 and the silicon-based substrate 1. Therefore, the raised microstructure 21 is set to a strip structure extending along the first direction or along the second direction, so that the raised microstructure 21 can have a longer size, increasing the volume of the raised microstructure 21, and the continuous strip structure has higher mechanical strength, avoiding damage or displacement of the raised microstructure 21, thereby improving the stability of the mask 100. The extension along the first direction or the second direction can be adjusted according to the actual application scenario, which improves flexibility and applicability.

[0136] See also Fig.10 In yet another embodiment, the protruding microstructures 21 are a plurality of independently arranged island structures, and the protruding microstructures 21 are formed on the first surface of the silicon-based substrate 1 outside the region of the evaporation opening 11 .

[0137] Multiple independently arranged island structures can provide a large number of contact points between the silicon-based substrate 1 and the seed layer 31, significantly increase the actual contact area, improve the stability and reliability of the connection, and at the same time help to evenly disperse the stress generated between the materials and avoid local cracking or peeling caused by stress concentration, thereby extending the service life of the mask 100 and improving its stability.

[0138] Furthermore, a plurality of island structures are disposed around the periphery of each evaporation opening 11 .

[0139] It can be understood that since the evaporation openings 11 need to be repeatedly evaporated, the edges of the evaporation openings 11 are more likely to cause the seed layer 31 to separate from the silicon-based substrate 1. Therefore, by surrounding the periphery of each evaporation opening 11 area with an island structure, the connection between the seed layer 31 and the silicon-based substrate 1 in the evaporation opening 11 area is made tighter, thereby increasing the tightness of the connection between the seed layer 31 and the silicon-based substrate 1, extending the service life of the mask plate 100 and improving its stability.

[0140] See also Figure 7 In one embodiment, a plurality of evaporation openings 11 are arranged in an array on a silicon-based substrate 1. The array arrangement can maximize the use of available space, and more evaporation openings 11 are evenly arranged on a limited silicon-based substrate 1, thereby improving the overall space utilization, so that as many evaporation openings 11 as possible can be arranged on a single silicon-based substrate 1, so that more patterns can be deposited simultaneously during a single evaporation, or the silicon-based substrate 1 can be divided into a plurality of sub-masks 100, so that each sub-mask 100 corresponds to an evaporation opening 11, thereby improving the output efficiency of the mask 100.

[0141] In a specific embodiment, the mask 100 is applied to micro-OLED, the silicon-based substrate 1 is a silicon wafer silicon-based substrate 1, and the material of the protruding microstructure 21 is SiO2 or SiN x The material of the adhesion promoting layer 23 is TiO2, the material of the seed layer 31 is titanium-chromium alloy, the material of the metal structure 32 is invar alloy, the thickness of the silicon-based substrate 1 is 0.5 mm to 0.8 mm, the width of the evaporation opening 11 along the first direction is 15 mm to 25 mm, the width of each protruding microstructure 21 along the first direction is 2 μm to 5 μm, the thickness of each protruding microstructure 21 is 1 μm to 3 μm, and the distance between any two adjacent protruding microstructures 21 is also 2 μm to 5 μm, the thickness of the adhesion promotion layer 23 is 0.5 μm to 2 μm, the thickness of the seed layer 31 is 1 μm to 4.5 μm, the thickness of the metal structure 32 is 1 μm to 5 μm, the width of a single pixel opening along the first direction is 1 μm to 10 μm, and the distance between any two adjacent pixel openings 33 is 2 μm to 15 μm. It should be noted that the evaporation opening 11, the raised microstructures 21 on both sides of the evaporation opening 11, the seed layer 31 and the metal structure 32 form a unit structure, such as Figure 8 What is shown is a unit structure, and the width of the unit structure along the first direction is 10 mm to 30 mm.

[0142] The above are only exemplary embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a mask, characterized in that: The following steps are involved: Providing a silicon-based substrate; wherein the silicon-based substrate is preset with a plurality of evaporation opening areas; forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area; forming a metal mask covering the protruding microstructure on the silicon-based substrate; The silicon-based substrate is etched to form an evaporation opening in the evaporation opening area preset on the silicon-based substrate.

2. The method for preparing a mask according to claim 1, characterized in that: The step of forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area comprises: Depositing a first dielectric layer on the first surface of the silicon-based substrate; The first dielectric layer is patterned to form a plurality of protruding microstructures outside the evaporation opening area.

3. The method for preparing a mask according to claim 2, characterized in that: After the step of forming a plurality of protruding microstructures on the first surface of the silicon-based substrate outside the evaporation opening area, the method further includes: An adhesion promoting layer is formed to cover the surface of the protruding microstructure and a surface of a portion of the silicon-based substrate that is not in the evaporation opening area; the adhesion promoting layer has an uneven surface.

4. The method for preparing a mask according to claim 3, characterized in that: The step of forming a metal mask covering the protruding microstructure on the silicon-based substrate comprises: forming a metal layer on the silicon-based substrate, wherein the metal layer covers the protruding microstructure; forming a first patterned photoresist on the metal layer; The area of ​​the metal layer not covered by the first patterned photoresist is etched to form the metal mask, wherein the metal mask includes metal sub-masks corresponding to the plurality of preset evaporation opening areas, and each of the metal sub-masks has a plurality of pixel openings arranged in an array.

5. The method for preparing a mask according to claim 3, characterized in that: Before the step of forming a metal mask covering the protruding microstructure on the silicon-based substrate, the method further includes: Forming a seed layer on the surface of the adhesion promoting layer on the silicon-based substrate, wherein the seed layer covers the protruding microstructure and the adhesion promoting layer, and the seed layer has a flat surface; The step of forming a metal mask covering the protruding microstructure on the silicon-based substrate comprises: forming a second patterned photoresist on the seed layer; Using an electroforming process to form a metal structure in the area on the seed layer that is not covered by the second patterned photoresist, to obtain the metal mask, wherein the metal mask includes metal sub-masks corresponding to the plurality of preset evaporation opening areas, each of the metal sub-masks having a plurality of pixel openings arranged in an array; After the step of etching the silicon-based substrate to form an evaporation opening in the evaporation opening area preset on the silicon-based substrate, the method further includes: The seed layer is patterned so that each pixel opening is connected to the corresponding evaporation opening.

6. The method for preparing a mask according to claim 5, characterized in that: The step of patterning the seed layer so that each of the pixel openings is connected to the corresponding evaporation opening comprises: Forming a third patterned photoresist on the metal structure, wherein the third patterned photoresist covers the surface area of ​​the metal structure except the pixel opening; The seed layer is etched using the third patterned photoresist and the metal structure as masks, and through holes connected to the evaporation openings are formed on the seed layer corresponding to each pixel opening, so as to connect each pixel opening to the corresponding evaporation opening.

7. The method for preparing a mask according to any one of claims 1 to 6, characterized in that: The step of etching the silicon-based substrate to form an evaporation opening in the evaporation opening area preset on the silicon-based substrate comprises: A photoresist formed on a second surface of the silicon-based substrate, wherein the second surface and the first surface are located on two opposite sides of the silicon-based substrate; Patterning the photoresist on the second surface to expose each of the evaporation opening areas; The silicon-based substrate at each of the evaporation opening regions is etched to form a plurality of the evaporation openings.

8. A mask, characterized in that: include: A silicon-based substrate, wherein a plurality of evaporation openings penetrating the silicon-based substrate are formed on the silicon-based substrate, and a convex microstructure is arranged in an area of ​​the first surface of the silicon-based substrate except for the evaporation openings; A metal mask, wherein the metal mask includes a metal structure and a seed layer, wherein the seed layer is covered on top of the raised microstructure, the metal structure is correspondingly arranged on top of the seed layer, and a plurality of connected pixel openings are opened on the metal main layer corresponding to each of the vapor deposition openings, and a through hole is formed at each of the pixel openings on the seed layer corresponding to each of the pixel openings for connecting the pixel opening with the corresponding vapor deposition opening.

9. The mask according to claim 8, characterized in that: An adhesion promoting layer is also arranged between the seed layer and the protruding microstructure, and the adhesion promoting layer covers the surface of the protruding microstructure and the surface of part of the silicon-based substrate that is not the evaporation opening area; the adhesion promoting layer has an uneven surface.

10. The mask according to claim 8, characterized in that: The protruding microstructures are multiple strip structures extending along the first direction and spaced apart along the second direction; or, the protruding microstructures are multiple strip structures extending along the second direction and spaced apart along the first direction, wherein the first direction is perpendicular to the second direction; and / or, The protruding microstructures are a plurality of independently arranged island structures, and the protruding microstructures are formed on the first surface of the silicon-based substrate outside the evaporation opening area.

11. The mask according to claim 8, characterized in that: A plurality of the evaporation opening arrays are arranged on the silicon-based substrate.

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