Composite mask and preparation method thereof

Abstract

The invention relates to the technical field of photomask substrates, in particular to a composite mask and a preparation method thereof.The preparation method comprises the following steps that a low-expansion-coefficient polymeric membrane material is selected, and plasma is adopted for cleaning; forming a cone-frustum-like hole with a taper angle in a set position on the surface of the polymer membrane material; cleaning the polymeric membrane material with the cone-frustum-like hole with the taper angle; obtaining a high-precision mask pattern according to the designed pattern; according to the high-precision mask pattern, a layer of magnetic metal film is deposited on the surface of the polymer film material through a magnetron sputtering method, and then the composite mask is manufactured. In the magnetron sputtering process, photoetching high-precision Mask is added, and the sputtering area is shaped, so that the hole precision is kept while the polymer film layer has magnetism, the thickness, precision, uniformity and the like of an organic layer material in the organic micromolecule evaporation process in the OLED manufacturing process can be improved, and the picture display effect of a display device is further improved.

Description

Technical Field

[0001] This invention relates to the field of photomask substrate technology, specifically to a composite photomask and its preparation method. Background Technology

[0002] OLED displays are a popular display technology, and the small-molecule OLED organic layer needs to be deposited through vapor deposition. The performance of this layer directly affects the display effect. To form red, green, and blue pixels, RGB needs to be precisely deposited onto the corresponding pixel points. Currently, FMMs (Fine Metal Masks) are used to separately deposit the RGB pixel light-emitting layers. FMMs are key fixtures in OLED device fabrication, covered with densely packed holes. During the vapor deposition process, OLED materials are deposited onto the backplane through these holes to achieve patterning.

[0003] FMMs (Fixed Masks) are mostly made of alloys or polymers with low coefficients of thermal expansion. Currently, the mainstream manufacturing process for FMMs involves wet etching of Invar alloys. However, Invar alloys are currently largely monopolized by Hitachi Metals of Japan, making them expensive. Furthermore, due to the isotropic nature of the etching solution, the resulting mask apertures are often too large, and precision is difficult to control. The current mainstream polymer FMM fabrication uses a low-thermal-expansion polyimide film as the substrate. First, laser-drilled apertures are made in the polymer film layer, followed by sputtering a magnetic metal film to imbue the substrate with magnetron magnetron sputtering. However, magnetron sputtering of the metal film easily leads to the polymer film clogging the apertures or adhering to the edges of the holes, affecting the mask's precision. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a composite mask and its preparation method, which solves the problem that magnetron sputtering coating in existing technologies can lead to clogging of the openings in polymer masks or metal adhesion at the edges, resulting in poor hole precision and further affecting the size, thickness, and uniformity of organic material deposition.

[0005] This invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a composite photomask, the method comprising the following steps:

[0007] Select a low coefficient of thermal expansion polymer membrane material and use plasma to clean the selected polymer membrane material;

[0008] After cleaning, fix the polymer membrane material and open a truncated cone-shaped hole with a cone angle at a predetermined position on the surface of the polymer membrane material;

[0009] The polymer film material with the conical-tapered hole is cleaned; the PI film after the hole is cleaned again to eliminate the impurity particles introduced by the laser processing.

[0010] The high-precision mask pattern is obtained by photoetching according to the designed pattern;

[0011] According to the high-precision mask pattern, a layer of magnetic metal film is deposited on the surface of the polymer film material by the magnetron sputtering method, and then the composite mask is made.

[0012] Further, the low-expansion coefficient polymer film material is a low-expansion coefficient polyimide PI film. By plasma bombardment of the substrate surface, on the one hand, the PI film surface impurities can be removed, and on the other hand, the PI film surface can be roughened, the bonding surface area can be increased, the free energy of the polyimide surface can be improved, and the adhesion between the subsequent film layers can be improved.

[0013] Further, the thickness of the low-expansion coefficient polyimide PI film is 5-100um.

[0014] Further, in the method, the laser equipment is used to open the conical-tapered hole on the set position on the surface of the polymer film material.

[0015] Further, in the method, the set position is set in the laser equipment through the space position model, and the conical-tapered hole is automatically opened by the laser equipment.

[0016] Further, in the method, the angle range of the conical-tapered hole is 0-90°.

[0017] Further, in the method, the photoetching process is to obtain a precise pattern according to the designed pattern after exposure, development and etching process.

[0018] Further, in the method, a layer of magnetic metal film is deposited on the surface of the polymer film material by bombarding the metal target material through the magnetron sputtering method. By increasing the photoetching high-precision mask during the magnetron sputtering process, the sputtering area is shaped, so that the polymer film layer has magnetism while maintaining the hole accuracy.

[0019] Further, the film thickness of the magnetic metal film is 200nm-100um.

[0020] The second aspect of the present application provides a composite mask prepared by the preparation method of the composite mask of the first aspect, and the composite mask is used for the production of OLED screen.

[0021] The beneficial effects of the present application are:

[0022] The present application improves the bonding force of the whole structure by sputtering the metal oxide intermediate layer, so that the low-expansion high-molecular film layer has magnetic properties and the interlayer bonding force is enhanced, and by increasing the sputtering mask, the precision of the opening is preserved, the thickness, precision, uniformity, etc. of the organic layer material in the organic small-molecule evaporation process in the OLED process are improved, and the picture display effect of the display device is further improved. The high-precision mask plate uses a photolithography process, which is mature and easy to implement and industrialize. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0024] Figure 1 is the process principle topology of the embodiment of the present application;

[0025] Figure 2 is a schematic diagram of the composite mask plate structure of the embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] Embodiment 1

[0028] As shown in Figure 1 and 2 , the present embodiment provides a preparation method of a composite mask plate, which is as follows:

[0029] (1) First, the high-molecular film material is cleaned by plasma, preferably low-expansion polyimide PI film. By bombarding the surface of the substrate with plasma, on the one hand, the impurities on the surface of the PI film can be removed, and on the other hand, the surface of the PI film can be roughened, the bonding surface area can be increased, the surface free energy of the polyimide can be improved, and the adhesion between the film layers in the subsequent film plating process can be improved. The thickness of the film material preferred in the present embodiment is 5um.

[0030] (2) Fix the cleaned PI film, and use a laser device to open a conical hole with a taper angle on the surface of the PI film layer at a specific position. The taper angle of the hole in this embodiment is preferably 1°.

[0031] (3) Clean the PI film after the hole is opened again to eliminate impurity particles introduced by the laser processing in step (2).

[0032] (4) According to the high-precision mask pattern, the mask is a photolithography process, and after exposure, development and etching processes, a precise patterning is obtained according to the designed pattern.

[0033] (5) A layer of magnetic metal film is deposited on the surface of the PI film by bombarding a specific metal target through a magnetron sputtering method. The preferred thickness of the coating in this embodiment is 200 nm.

[0034] In this embodiment, a high-precision mask is added during the magnetron sputtering process to shape the sputtering area, so that the polymer film layer has magnetism while maintaining the hole precision. The problem of poor hole precision caused by magnetron sputtering coating, which leads to hole blockage or edge metal adhesion of the high polymer hole mask, and further affects the size, thickness and uniformity of the deposited organic material, is solved.

[0035] Example 2

[0036] Based on Example 1, as shown in Figure 1 and 2 , this embodiment provides a preparation method of a composite mask, specifically as follows:

[0037] (1) First, clean the polymer film material by plasma, preferably low-expansion polyimide PI film. Bombarding the surface of the substrate by plasma can remove impurities on the surface of the PI film, and on the other hand, it can roughen the surface of the PI film, increase its bonding surface area, increase the surface free energy of the polyimide, and improve the adhesion between the film layers in the subsequent coating process. The preferred thickness of the film material in this embodiment is 100 um.

[0038] (2) Fix the cleaned PI film, and use a laser device to open a conical hole with a taper angle on the surface of the PI film layer at a specific position. The taper angle of the hole in this embodiment is preferably 89°.

[0039] (3) Clean the PI film after the hole is opened again to eliminate impurity particles introduced by the laser processing in step (2).

[0040] (4) According to the high-precision mask pattern, the mask is a photolithography process, and after exposure, development and etching processes, a precise patterning is obtained according to the designed pattern.

[0041] (5) through magnetron sputtering method bombarding specific metal target to deposit a layer of magnetic metal film on the surface of PI film material, the preferred film thickness of this embodiment is 100um.

[0042] In this embodiment, by adding a high-precision mask to the magnetron sputtering process, the sputtering area is shaped, so that the polymer film layer has magnetism while maintaining the hole precision. The problem of blocking holes or edge adhesion of metal in the polymer open hole mask caused by magnetron sputtering film plating, which leads to poor hole precision and further affects the size, thickness and uniformity of organic material deposition, is solved.

[0043] Embodiment 3

[0044] The composite mask plate is prepared by the preparation method of the composite mask plate of the above embodiment, and is used for the production of an OLED screen.

[0045] In summary, the present application improves the overall structure by sputtering metal oxide interlayer, which enhances the bonding force between layers, and increases the thickness, precision and uniformity of organic layer material during the organic small molecule evaporation process in OLED manufacturing, and further improves the display effect of display devices. The high-precision mask plate uses a photolithography process, which is mature and easy to implement, and is convenient for industrialization.

[0046] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a composite photomask, characterized in that, The method includes the following steps: Select a low coefficient of thermal expansion polymer membrane material and use plasma to clean the selected polymer membrane material; After cleaning, fix the polymer membrane material and open a truncated cone-shaped hole with a cone angle at a predetermined position on the surface of the polymer membrane material; Cleaning of polymer membrane materials with cone-shaped holes resembling truncated cones; High-precision photomask patterns are created by photolithography, following the designed design. Based on a high-precision photomask pattern, a magnetic metal thin film is deposited on the surface of a polymer film material using magnetron sputtering, thereby creating a composite photomask.

2. The method for preparing a composite photomask according to claim 1, characterized in that, The low coefficient of thermal expansion polymer membrane material is a low coefficient of thermal expansion polyimide (PI) membrane.

3. The method for preparing a composite photomask according to claim 2, characterized in that, The thickness of the low coefficient of thermal expansion polyimide (PI) film is 5-100 μm.

4. The method for preparing a composite photomask according to claim 1, characterized in that, In the method, a laser device is used to create a truncated cone-shaped hole with a tapered angle at a predetermined position on the surface of the polymer film.

5. The method for preparing a composite photomask according to claim 4, characterized in that, In the method, the position is set in the laser device by setting a spatial position model, and the laser device automatically opens a truncated cone-shaped hole with a conical angle.

6. The method for preparing a composite photomask according to claim 5, characterized in that, In the method, the angle range of the cone-shaped frustum-like hole with a conical angle is 0-90°.

7. The method for preparing a composite photomask according to claim 1, characterized in that, In the method described, the photolithography process involves exposure, development, and etching processes to obtain a precise pattern according to the designed design.

8. The method for preparing a composite photomask according to claim 1, characterized in that, In the method, a magnetic metal film is deposited on the surface of a polymer film by bombarding a metal target with magnetron sputtering.

9. The method for preparing a composite photomask according to claim 1, characterized in that, The coating thickness of the magnetic metal thin film is 200nm-100um.

10. A composite photomask, said composite photomask being prepared by the method for preparing a composite photomask according to any one of claims 1-9, characterized in that, The composite photomask is used in the production of OLED screens.

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