A method for preparing a composite mask

Abstract

A method for preparing a composite mask includes the following steps: S1: providing a photolithographic pattern on the mask; S2: removing a portion of the photoresist through the photolithographic pattern; S3: electroforming the mask and uniformly coating the mask with a polymer film layer; S4: curing the polymer film layer; S5: pulse drilling the cured polymer film layer to produce a truncated cone-shaped hole with a taper angle, wherein the inlet of the hole is larger than the outlet aperture, and the taper angle range is controlled to be 30°-120°; S6: removing the remaining photoresist with a cleaning solution; S7: cleaning the laser-opened residue, drying the mask, and completing the preparation. The present invention effectively reduces the thermal expansion of the electroformed mask by adding a layer of metal-bonded polymer low thermal expansion coefficient material to the electroformed mask. Through holes with a certain taper angle are opened by the action of a femtosecond laser, thereby solving the problem of achieving thickness while being difficult to effectively control the taper angle in electroforming.

Description

Technical Field

[0001] The present invention relates to the field of electronic equipment processing, and in particular to a method for preparing a composite mask. Background Art

[0002] Fine metal masks (FMMs) are key tools used in the production of OLED devices. They typically use low-thermal expansion metals or alloys as substrates. Currently, there are two mainstream FMM production processes: etching and electroforming.

[0003] The drawback of the etching method is that the etching liquid has an isotropic etching effect, and the hole size is close to the thickness. In addition, the thickness of the Invar alloy used for etching is relatively thick, about 30um, so the hole size is large and the high PPI goal cannot be achieved.

[0004] Electroforming can effectively control the thickness of the mask. Due to the difficulty of electroforming binary alloys, most manufacturers use single magnetic metals such as Ni as the substrate. However, the thermal expansion coefficient of Ni itself reaches 1.3*10 -5 / K, which is far from meeting the requirements of OLED evaporation for low thermal expansion coefficient (3*10 -6 / K). In addition, it is difficult to control the taper angle while controlling the substrate thickness in electroforming.

[0005] Therefore, the current electroforming process is difficult to meet the requirements of OLED evaporation, and a new mask preparation method is urgently needed. Summary of the Invention

[0006] The purpose of the present invention is to effectively overcome the difficulties of thermal expansion caused by the electroforming substrate and precise control of the opening angle in the mask preparation process.

[0007] Therefore, a method for preparing a composite mask is proposed, and the specific technical solution is as follows:

[0008] A method for preparing a composite mask, characterized by:

[0009] The steps include:

[0010] S1: A photoresist pattern is set on the mask;

[0011] S2: remove part of the photoresist through the photolithography pattern;

[0012] S3: Electroforming mask, evenly coating the polymer film layer on the mask;

[0013] S4: solidifying the polymer film layer into shape;

[0014] S5: Pulse drilling is performed on the cured polymer film layer to open a quasi-conical hole with a cone angle. The inlet of the hole is larger than the outlet aperture, and the cone angle range is controlled within 30°-120°;

[0015] S6: Remove the remaining photoresist with cleaning solution;

[0016] S7: Clean the laser opening residue and dry the mask to complete the preparation.

[0017] In order to better implement the present invention, it is possible to further:

[0018] In the above-mentioned S4, the polymer film layer is solidified and formed by laser heat treatment or baking.

[0019] Furthermore: the polymer is made of a material with a low thermal expansion coefficient, and the material of the polymer film layer is selected from polyimide, polypropylene, polyethylene terephthalate or graphene.

[0020] Furthermore: in said S5, drilling is performed by using femtosecond laser pulses of a Yb:KGW femtosecond laser.

[0021] Furthermore, the parameters of the Yb:KGW femtosecond laser are as follows: central wavelength 1024nm, average power 6W, pulse duration 190fs, pulse repetition rate 200KHz, maximum pulse energy 1mJ, and the taper angle is adjusted by changing the pulse amplitude 1um-100um. The taper angle is the cone angle.

[0022] Furthermore: the inlet aperture of the hole is 1-40 μm.

[0023] Furthermore: the thickness of the polymer film layer is controlled between 5um and 100um.

[0024] Furthermore: the cleaning liquid is hydrofluoroether.

[0025] Furthermore: the polymer film layer is made of polyimide.

[0026] Furthermore: the mask is made of Ni, Fe, and Co.

[0027] The beneficial effects of the present invention are:

[0028] First, the present invention solves the thermal expansion problem of the electroforming mask by adding a layer of high molecular weight low thermal expansion coefficient material that adheres to the metal to the electroforming mask. Due to the adhesion of the added layer, the thermal expansion of the electroforming mask can be effectively reduced.

[0029] Secondly, the present invention performs aligned laser drilling on the added material layer, and uses the action of a femtosecond laser to drill through holes with a certain taper angle, thereby solving the difficulty of effectively controlling the taper angle during the thinning process of electroforming. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a specific flow chart of the work of the present invention;

[0031] Figure 2 Schematic diagram of photoresist coating;

[0032] Figure 3 Schematic diagram for making holes;

[0033] Figure 4 Complete the schematic diagram for the hole;

[0034] Figure 5 Schematic diagram of electroforming;

[0035] Figure 6 Schematic diagram of electroforming completion;

[0036] Figure 7 Schematic diagram of polymer coating;

[0037] Figure 8 Schematic diagram of polymer and metal connection;

[0038] Figure 9 Schematic diagram of laser drilling;

[0039] Figure 10 Schematic diagram after the hole is completed;

[0040] The accompanying drawings in the figure illustrate cathode plate 1, photoresist 2, UV light 3, mask 4, electroplating solution 5, metal block 6, anode plate 7, polymer film 8, and laser 9. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0042] like Figure 1 As shown:

[0043] A method for preparing a composite mask comprises the following steps:

[0044] S1: If Figure 2 As shown, a photoresist is provided on the cathode plate, and the thickness of the photoresist is 3-30um.

[0045] S2: If Figure 3 and Figure 4 As shown, a mask hole pattern is set on the surface of the photoresist, and the excess photoresist is removed by UV light exposure and development;

[0046] S3: If Figure 5 As shown, an anode plate is arranged above the cathode plate, and an electroplating solution is arranged between the cathode plate and the anode plate to obtain an electroformed metal layer. Figure 6 As shown, the thickness of the electroformed metal layer is consistent with the thickness of the photoresist. In this embodiment, the metal layer is Ni. The metal layer can also be made of Fe, Co or a combination of other elements;

[0047] S4: As Figure 7 As shown, a polymer film layer is evenly coated on the surface of the metal layer and the photoresist layer, and the thickness of the polymer film layer is controlled between 3-50 μm. The polymer uses a low thermal expansion coefficient material, and the material of the polymer film layer is selected from polyimide, polypropylene, polyethylene terephthalate or graphene.

[0048] The polymer film layer is solidified and formed, specifically, the polymer film layer is solidified and formed by laser heat treatment or baking.

[0049] S5: If Figure 8 As shown, the cathode plate and the photoresist are removed to obtain a polymer film layer with a metal block on the lower surface.

[0050] S6: As Figure 9 As shown in the figure, a Yb:KGW femtosecond laser is used to perform pulse drilling on the cured polymer film layer through femtosecond laser pulses to open a truncated cone hole with a cone angle. The inlet of the hole is larger than the outlet aperture. The inlet aperture size is 1-40um, and the cone angle range is controlled in the range of 30°-120°. The specific structure is as follows Figure 10 shown.

[0051] The femtosecond laser has a central wavelength of 1024nm, an average power of 6W, a pulse duration of 190fs, a pulse repetition frequency of 200KHz, a maximum pulse energy of 1mJ, and the taper angle can be adjusted by changing the pulse amplitude from 1um to 100um.

[0052] S7: Clean with hydrofluoroether, laser opening residue, dry, and complete.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0054] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a composite mask, characterized in that: The steps include: S1: A photoresist pattern is set on the mask; S2: remove part of the photoresist through the photolithography pattern; S3: Electroforming mask, evenly coating the polymer film layer on the mask; S4: solidifying the polymer film layer into shape; S5: Pulse drilling is performed on the cured polymer film layer to form a quasi-conical hole with a taper angle. The inlet of the hole is larger than the outlet aperture, and the taper angle range is controlled to be 30°-120°. The drilling is performed by using a femtosecond laser pulse of a Yb:KGW femtosecond laser. The parameters used by the Yb:KGW femtosecond laser are: central wavelength 1024nm, average power 6W, pulse duration 190fs, pulse repetition rate 200kHz, maximum pulse energy 1mJ, and the taper angle is adjusted by changing the pulse amplitude from 1um to 100um. S6: Remove the remaining photoresist with cleaning solution; S7: Clean the laser opening residue and dry the mask to complete the preparation.

2. The method for preparing a composite mask according to claim 1, wherein: In the above-mentioned S4, the polymer film layer is solidified and formed by laser heat treatment or baking.

3. The method for preparing a composite mask according to claim 2, wherein: The polymer is made of a material with a low thermal expansion coefficient, and the material of the polymer film layer is made of polyimide, polypropylene or polyethylene terephthalate.

4. The method for preparing a composite mask according to claim 1, wherein: The inlet aperture of the hole is 1□40um.

5. The method for preparing a composite mask according to claim 3, wherein: The thickness of the polymer film layer is controlled between 5um□100um.

6. The method for preparing a composite mask according to claim 1, wherein: The cleaning liquid is hydrofluoroether.

7. The method for preparing a composite mask according to claim 5, wherein: The polymer film layer is made of polyimide.

8. The method for preparing a composite mask according to claim 1, wherein: The mask is made of Ni, Fe, and Co.

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