Preparation method of mask plate for evaporation of high-resolution OLED (Organic Light Emitting Diode)

Abstract

The invention discloses a preparation method of a mask plate for evaporation of a high-resolution OLED (Organic Light Emitting Diode). The preparation method comprises the following steps: S1) covering one side surface of a glass substrate with a metal layer; (S2) a light resistor is formed on the side, away from the substrate layer, of the metal layer, a plurality of first through holes are formed in the light resistor, and the first through holes correspond to a to-be-evaporated area on the display substrate; s3) etching a region, which is not covered by the photoresist, on the metal layer, and forming a second through hole communicated with the first through hole on the metal layer; s4) removing the light resistance; and S5) performing plasma etching on the area, which is not covered by the metal layer, on the glass substrate, and forming a third through hole communicated with the second through hole in the glass substrate. The mask plate is formed through cooperation of the glass substrate and the metal layer, the evaporation pattern is defined through the metal layer (provided with the second through holes), and the high-resolution effect of the display substrate can be achieved when the mask plate is used in cooperation with the high-density third through holes formed in the glass substrate.

Description

Technical Field

[0001] This invention relates to the field of mask processing technology, and in particular to a method for preparing a mask for high-resolution OLED evaporation. Background Technology

[0002] For OLED display products, the evaporation of RGB organic materials is required. The key fixture for evaporation is the FMM (Fine Metal Mask), which is made of metal. Magnetic attraction via a magnetic plate allows for more precise definition of the OLED evaporation pattern. In existing technologies, the main material of the fine metal mask is an iron-nickel alloy. The mask is primarily manufactured using a wet chemical etching process, followed by appropriate photolithography.

[0003] The pixel density (ppi) of a display substrate directly determines the fineness of the displayed image. To increase ppi, the ppi of the fine metal mask (FMM) must first be increased. However, the preparation and use of fine metal masks present the following problems: on the one hand, ultra-thin, defect-free iron-nickel materials are controlled by Hitachi Metal of Japan; on the other hand, when wet etching iron-nickel alloys, the lateral etching characteristics of wet etching prevent the opening density of the iron-nickel alloy material from being increased, thus affecting its ppi and consequently the ppi of the display substrate after its vapor deposition. Using double-sided etching to increase the opening density also complicates the process. Moreover, for current FMM preparation methods, 600 ppi is the upper limit of existing technology. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a high-resolution OLED evaporation mask. The mask is formed by combining a glass substrate and a metal layer. The evaporation pattern is defined by the metal layer (which has a second through-hole). Combined with the high-density third through-hole formed on the glass substrate, it can achieve a high-resolution display substrate when applied.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing a mask for high-resolution OLED evaporation, comprising the following steps:

[0006] S1) A metal layer is coated on one side surface of the glass substrate;

[0007] S2) A photoresist is formed on the side of the metal layer away from the substrate layer. The photoresist has a plurality of first through holes, and the first through holes are disposed corresponding to the areas to be vapor-deposited on the display substrate.

[0008] S3) Etch the area on the metal layer that is not covered by the photoresist to form a second through hole on the metal layer that is connected to the first through hole. The second through hole is disposed in correspondence with the area to be vaporized on the display substrate.

[0009] S4) Remove light resistance;

[0010] S5) Plasma etching is performed on the area of ​​the glass substrate not covered by the metal layer to form a third through hole that communicates with the second through hole on the glass substrate. The third through hole is correspondingly set with the area to be vaporized on the display substrate.

[0011] As a further optimization, the metal layer in S1 is applied to the glass substrate by physical sputtering or chemical plating.

[0012] As a further optimization, the metal layer in S1 is first applied to the glass substrate by physical sputtering and then by electroplating.

[0013] As a further optimization, the metal layer in S1 includes at least a magnetically conductive material that can be used to attract the magnetic plate during the vapor deposition of the display substrate.

[0014] As a further optimization, the thickness of the metal layer in S1 is 1-25 μm, and its thinner thickness can avoid lateral etching of the second via.

[0015] As a further optimization, the photoresist described in S2 is a composition of a polymer resin, a photosensitizer, and a solvent.

[0016] As a further optimization, the etching in S3 is wet etching using an etching solution, which includes one or more of nitric acid solution, aqua regia, ferric chloride solution, copper sulfate solution, ammonium persulfate solution, and potassium persulfate solution, and the temperature of the wet etching is 15-50°C.

[0017] As a further optimization, photoresist is removed in S4 using an alkaline solution.

[0018] As a further optimization, the plasma used for plasma etching in S5 is ICP or ECR, and the plasma etching gas includes one or more of CF4, SF6, C3F8, Ar, Kr, and O2. The etching conditions are: etching chamber pressure of 1-100 mTorr and temperature of -20-100℃.

[0019] As a further optimization, the second through hole and the third through hole have the same vertical projection, that is, they have the same hole diameter.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. A mask is formed by combining a glass substrate and a metal layer. The metal layer (which has a second through-hole) defines the vapor deposition pattern. Combined with the high-density third through-hole formed on the glass substrate, it can achieve a high-resolution display substrate when applied.

[0022] 2. A third through-hole is formed on the metal layer by plasma etching on the glass substrate at the second through-hole. The formation process of the third through-hole can avoid isotropic etching, that is, avoid the third through-hole occupying a large space laterally, so as to form a high density of third through-holes. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation method of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the application of a photomask. Detailed Implementation

[0025] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0026] like Figure 1 As shown, the present invention provides a method for preparing a mask for high-resolution OLED evaporation, specifically including the following steps:

[0027] S1) A metal layer 200 is covered on one side surface of the glass substrate 100;

[0028] S2) A photoresist 300 is formed on the side of the metal layer 200 away from the substrate layer 100. The photoresist 300 has a plurality of first through holes 301, and the first through holes 301 are configured to correspond to the areas to be vaporized on the display substrate.

[0029] S3) Etch the area on the metal layer 200 that is not covered by the photoresist 300 (i.e. the area exposed by the first via 301) to form a second via 201 on the metal layer 200 that is connected to the first via 301. The formed second via 201 is correspondingly set to the area to be vaporized on the display substrate.

[0030] S4) Remove 300 μm of photoresist;

[0031] S5) Plasma etching is performed on the area of ​​the glass substrate 100 not covered by the metal layer 200 (i.e. the area exposed by the second through hole 201) to form a third through hole 101 connected to the second through hole 201 on the glass substrate 100. The formed third through hole 101 is correspondingly set to the area to be vaporized on the display substrate.

[0032] Combination Figure 2As shown, in this invention, the glass substrate 100 is used as the main body of the mask plate, and its thickness can be 10-200μm. The ultra-thin glass substrate 100 can be processed by plasma etching to form through holes (i.e., the third through hole 101) that match the area to be vaporized on the display substrate. Specifically, a metal layer 200 is first covered on one side surface of the glass substrate 100. The metal layer 200 and the glass substrate 100 form a mask. The function of the metal layer 200 is to be attracted to the magnetic plate to position the mask when it is used. A photoresist 300 is covered on the metal layer 200. The first through-hole 301 on the photoresist 300 matches the area to be vaporized on the display substrate. The area exposed at the first through-hole 301 on the metal layer 200 is removed by wet etching. A second through-hole 201 matching the area to be vaporized on the display substrate is then formed on the metal layer 200. The photoresist 300 is removed but the metal layer 200 is retained. The area exposed at the second through-hole 201 on the glass substrate 100 is removed by plasma etching. A third through-hole 101 matching the area to be vaporized on the display substrate is then formed on the glass substrate 100. In application, the mask is positioned by adsorbing the metal layer 200 by the magnetic plate, and the second through hole 201 and the third through hole 101 expose the area to be vaporized on the display substrate so as to facilitate vapor deposition on the display substrate. Preferably, the second through hole 201 and the third through hole 101 have the same vertical projection.

[0033] This invention uses a glass substrate 100 as the main body of the mask to replace conventional iron-nickel alloy material. In conjunction with the second through-hole 201 on the metal layer 200, a third through-hole 101 matching the area to be deposited on the display substrate can be formed on the glass substrate 100 by plasma etching. Due to the use of plasma etching, it has good directionality, which can ensure the relative consistency of the sidewalls of the third through-hole 101 in the longitudinal direction. This avoids the isotropic etching problem (i.e., longitudinal etching and lateral etching are carried out simultaneously) that occurs when conventional iron-nickel alloy and other materials are wet etched. This avoids the through-holes on the iron-nickel alloy from extending laterally while extending longitudinally and occupying lateral space. Based on the less lateral space occupied, the third through-hole 101 can be guaranteed to have a high density (i.e., a large number of third through-holes in a certain area). After applying this mask to deposit on the display substrate, the display substrate can have a high resolution.

[0034] Preferably, in S1, the metal layer 200 is applied to the glass substrate by physical sputtering or chemical plating. Physical sputtering (physical vapor deposition) is a physical vapor deposition (PVD) technology that uses high-energy particles to bombard the surface of a target material in a vacuum environment, causing the target atoms or molecules to be sputtered and deposited on the substrate surface to form a thin film. This technology is widely used in semiconductors, optical coatings, decorative coatings, functional thin films, and other fields. Chemical plating does not require electricity. It is based on the principle of redox reaction, using a strong reducing agent in a solution containing metal ions to reduce the metal ions to metal and deposit them on the surface of various materials to form a dense coating. Commonly used chemical plating solutions include, but are not limited to, chemical silver plating solutions, chemical nickel plating solutions, chemical copper plating solutions, chemical cobalt plating solutions, chemical nickel-phosphorus plating solutions, and chemical nickel-phosphorus-boron plating solutions.

[0035] In addition, the metal layer 200 in S1 can also be applied to the glass substrate by physical sputtering and then electroplating. The specific process is to generate a metal conductive layer by physical sputtering and then plate another metal or alloy on the surface of the metal conductive layer by electroplating electrolysis principle.

[0036] Preferably, the metal layer 200 in S1 can be a single material or an alloy material, but the metal layer 200 must include at least a magnetically conductive material for adsorption with the magnetic plate to position the mask plate.

[0037] The thickness of the metal layer 200 in S1 is 1-25μm. Since the metal layer 200 has a relatively thin thickness, when the second via 201 is formed on the metal layer 200 by wet etching, the lateral etching generated can be ignored, so that the sidewall of the second via 201 has good relative consistency in the longitudinal direction.

[0038] When wet etching is used on the metal layer 200, the etching solution can be one or more of the following: nitric acid solution, aqua regia, ferric chloride solution, copper sulfate solution, ammonium persulfate solution, and potassium persulfate solution. The specific etching solution or a combination of several can be selected based on the specific composition of the metal layer. The etching process follows existing etching techniques (including concentration, time, and temperature), such as a wet etching temperature of 15-50℃. Since the wet etching targets the metal layer 200, it will not affect the photoresist 300 or the glass substrate 100 during the etching process.

[0039] In S2, the photoresist 300 is a composition of polymer resin, photosensitizer, and solvent, and can be removed by an alkaline solution. The removal of the photoresist 300 will not affect the metal layer 200 or the glass substrate 100.

[0040] The plasma used in S5 for plasma etching is either ICP or ECR, and the etching gas includes one or more of CF4, SF6, C3F8, Ar, Kr, and O2. The etching chamber pressure is 1-100 mTorr. The area where the glass substrate is located during etching is called the substrate region. The temperature of the etching chamber and the substrate region can be independently controlled, with a temperature range of -20 to 100 degrees Celsius. A preferred implementation method is to use a low temperature for the substrate region (e.g., 1-10°C) and a high temperature for the chamber (50-70°C). During the plasma etching process, F is used for chemical etching with the glass substrate, Ar and Kr are used to provide bombardment capability, and O is used to eliminate byproducts generated during the etching process. The combination of various etching gases ensures the forming quality of the third through-hole 101.

[0041] This application forms a mask by cooperating a glass substrate 100 and a metal layer 200, defines a vapor deposition pattern by the metal layer 200 (which has a second through hole 201), and combines it with the high-density third through holes 101 formed on the glass substrate 100, which can achieve a high-resolution (high-resolution) effect for the display substrate when applied.

[0042] The mask prepared by the method of this application was tested and found that the display substrate can achieve a pixel density of 1200-1300 ppi after evaporation. Compared with the 250-300 ppi of notebook displays and the 400-500 ppi of mobile phone displays, the mask of this application has a better evaporation effect.

[0043] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing a mask for high-resolution OLED evaporation, characterized in that, Includes the following steps: S1) A metal layer is coated on one side surface of the glass substrate; S2) A photoresist is formed on the side of the metal layer away from the substrate layer. The photoresist has a plurality of first through holes, and the first through holes are disposed corresponding to the areas to be vapor-deposited on the display substrate. S3) Etch the area on the metal layer that is not covered by the photoresist to form a second through hole on the metal layer that is connected to the first through hole. The second through hole is disposed in correspondence with the area to be vaporized on the display substrate. S4) Remove light obstruction; S5) Plasma etching is performed on the area of ​​the glass substrate not covered by the metal layer to form a third through hole that communicates with the second through hole on the glass substrate. The third through hole is correspondingly set with the area to be vaporized on the display substrate.

2. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The metal layer mentioned in S1 is applied to the glass substrate by physical sputtering or chemical plating.

3. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The metal layer described in S1 is applied to the glass substrate by first physical sputtering and then electroplating.

4. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The metal layer described in S1 includes at least a magnetically conductive material.

5. The method for preparing a high-resolution OLED evaporation mask according to claim 1 or 4, characterized in that, The thickness of the metal layer in S1 is 1-25 μm.

6. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The photoresist described in S2 is a composition of polymer resin, photosensitizer, and solvent.

7. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The etching described in S3 is wet etching using an etching solution, which includes one or more of the following: nitric acid solution, aqua regia, ferric chloride solution, copper sulfate solution, ammonium persulfate solution, and potassium persulfate solution. The temperature of the wet etching is 15-50°C.

8. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, In S4, photoresist is removed using an alkaline solution process.

9. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The plasma used for plasma etching described in S5 is ICP or ECR, and the plasma etching gas includes one or more of CF4, SF6, C3F8, Ar, Kr, and O2. The etching conditions are: etching chamber pressure of 1-100 mTorr and temperature of -20-100℃.

10. The method for preparing a high-resolution OLED evaporation mask according to claim 1, characterized in that, The second through hole and the third through hole have the same vertical projection.

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