A method for preparing a high-precision anode for a silicon-based OLED display device

Abstract

The present invention discloses a method for preparing a high-precision anode of a silicon-based OLED display device. The anode metal film layer of the high-precision anode of the silicon-based OLED display device is a silver film layer. When etching the silver film layer, an alkyl gas is used as an etching gas and an inert gas is used as a carrier gas for dry etching. The present invention adopts a dry etching process to etch the silver film of the anode metal film layer, and prepares a high-precision anode by controlling the etching gas. The high-precision anode can meet the micron-level pixel resolution of the silicon-based Micro OLED, and significantly improves the reflectivity of the anode to more than 98%, and has good conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a method for preparing a high-precision anode of a silicon-based OLED display device. Background Art

[0002] With the rise of the concept of the metaverse, the market share of wearable augmented reality (AR) and virtual reality (VR) has grown rapidly, and various display technologies used in head-mounted displays have attracted people's interest. The display screen is one of the core components of VR / AR head displays. Among the many micro-display technologies, silicon-based Micro OLED has the characteristics of high pixel density, low power consumption, small size, fast response speed, large viewing angle, and self-luminescence, providing an economical solution for AR / VR applications.

[0003] However, the brightness of existing silicon-based Micro OLED full-color products on the market is generally low, which restricts the development of silicon-based Micro OLED products. Therefore, improving the brightness of silicon-based Micro OLED products is a unanimous pursuit. In top-emitting silicon-based Micro OLED devices, the reflectivity of the anode material is crucial for the preparation of high-brightness silicon-based Micro OLED devices. Commonly used anode metal materials in OLED display devices are Al and Ag. The reflectivity of Al to visible light is about 90%, and the reflectivity of Ag to visible light is about 98%. Using metal Ag as the anode material, combined with other optical structures, can significantly improve the brightness of silicon-based Micro OLEDs compared to using Al as the anode material.

[0004] However, in silicon-based Micro OLEDs, in order to achieve high pixel resolution, the accuracy of preparing the anode needs to reach 0.5um or even higher. The wet etching process is isotropic, and there is side etching when etching silver. The wet etching process cannot meet the high-precision requirements of the Ag electrode in silicon-based Micro OLEDs. The existing dry etching process often uses chlorine as a reaction gas when etching the Ag film. Chlorine and silver will generate a non-volatile product AgCl, which remains on the surface of the substrate. The by-product is difficult to remove, affecting the reflectivity of the anode. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a high-precision anode for a silicon-based OLED display device, which adopts a dry etching process to etch the silver film of the anode metal film layer, and prepares a high-precision anode by controlling the etching gas. It can meet the micron-level pixel resolution of the silicon-based Micro OLED, and significantly improve the reflectivity of the anode to more than 98%, and has good conductivity.

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

[0007] A method for preparing a high-precision anode of a silicon-based OLED display device, wherein the anode metal film layer of the high-precision anode of the silicon-based OLED display device is a silver film layer, and when etching the silver film layer, alkyl gas is used as etching gas and inert gas is used as carrier gas for dry etching.

[0008] Furthermore, in the mixed gas of the alkyl gas and the inert gas, the volume proportion of the alkyl gas is 20 to 100%.

[0009] The alkyl gas is at least one of methane and ethane; the inert gas is at least one of nitrogen and argon.

[0010] The gas flow rate of the mixed gas of the gas and the inert gas is 5 to 50 sccm.

[0011] The method for preparing a high-precision anode of a silicon-based OLED display device comprises the following steps:

[0012] (1) Depositing a composite laminated film of Ti and TiN on the surface of a silicon substrate with CMOS circuit drive;

[0013] (2) depositing an Ag film on the composite laminated film of Ti and TiN;

[0014] (3) depositing an anode protective film on the Ag film;

[0015] (4) coating, exposing, and developing the surface of the anode protective film to prepare an anode pattern;

[0016] (5) performing dry etching on the anode protection film to etch away the anode protection film not covered by the photoresist;

[0017] (6) Dry etching the Ag film;

[0018] (7) placing the silicon substrate in N-methylpyrrolidone for rinsing to remove etching byproducts and photoresist on the side wall of the Ag film;

[0019] (8) dry etching the anode protective film on the surface of the Ag film to obtain a silicon substrate with the Ag film completely exposed;

[0020] (9) depositing an anode protection film to fill the trenches between the Ag film patterns and completely cover the Ag film;

[0021] (10) The anode protection film on the surface of the Ag film is removed until it leaks out of the surface of the Ag film, and then cleaned. The anode protection film is a silicon oxide film, a silicon nitride film, or a composite laminated film of silicon oxide and silicon nitride.

[0022] Furthermore, in step (5) and step (8), carbon tetrafluoride is used as an etching gas and an inert gas is used as a carrier gas to perform dry etching.

[0023] The thickness of the Ag film is 50-200 nm.

[0024] The thickness of the composite laminated film of Ti and TiN is 2-20 nm.

[0025] In step (6), the etching depth of the Ag film is equal to the thickness of the silver film layer.

[0026] The invention provides a method for preparing a high-precision anode of a silicon-based OLED display device, wherein a dry etching process is used to etch the silver film of the anode metal film layer, and a high-precision anode is prepared by controlling the etching gas. When etching the anode metal film layer, an alkyl gas is used as the etching gas, and an inert gas is used as the carrier gas to dry-etch the anode Ag film, and the alkyl gas reacts with Ag to generate a byproduct Ag. x H y Unstable. As dry etching proceeds, the byproduct Ag generated by the alkyl gas and Ag x H y Decomposition occurs and the cavity is pumped out by the vacuum pump. The bottom of the Ag anode pattern is clean and free of residue, and only the side walls have byproduct Ag-F-polymer residues that can be washed away. After subsequent cleaning and rinsing processes, the residues on the side walls can be completely removed; ultimately, a high-precision silicon-based OLED display device anode can be obtained.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention adopts a dry etching process to etch the silver film of the anode metal film layer, and uses alkyl gas as the etching gas. The etching byproducts generated during the etching process are easily decomposed and can be pumped out of the cavity by a vacuum pump. The bottom of the Ag anode pattern is clean and has no residue, and a small amount of residue on the side wall is also easy to clean and remove;

[0029] 2 When etching the anode protection film layer, the present invention uses carbon tetrafluoride as the etching gas and uses an inert gas with good vertical etching performance as the carrier gas to ensure that the anode pattern can be accurately transferred to the surface of the silver film, and accurately etches the anode pattern through the dry etching process of the silver film; thereby avoiding the problems of slow etching rate and non-volatile etching by-products in conventional chlorine dry etching of Ag.

[0030] 3. Before depositing the anode silver film, the present invention also deposits a composite laminated film of Ti and TiN on the surface of the silicon substrate, and the film layer can improve the adhesion between the silicon substrate and the Ag film layer.

[0031] 4. The Ag anode prepared using this method can meet the micron-level pixel resolution of silicon-based Micro OLED, and significantly improve the reflectivity of the anode to more than 98%, and has good conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a silicon substrate with a CMOS driving circuit;

[0033] Figure 2 is a schematic diagram of step (1) in the embodiment;

[0034] Figure 3 is a schematic diagram of step (2) in the embodiment;

[0035] Figure 4 is a schematic diagram of step (3) in the embodiment;

[0036] Figure 5 is a schematic diagram of step (4) in the embodiment;

[0037] Figure 6 is a schematic diagram of step (5) in the embodiment;

[0038] Figure 7 is a schematic diagram of step (6) of the embodiment;

[0039] Figure 8 is a schematic diagram of step (7) in the embodiment;

[0040] Fig. 9 is a schematic diagram of step (8) in the embodiment;

[0041] Fig.10 is a schematic diagram of step (9) in the embodiment;

[0042] Fig.11 is a schematic diagram of step (10) in the embodiment;

[0043] Fig.12 is the reflectivity of Ag after coating at different wavelength spectra;

[0044] Fig.13 This is the SEM image of the Ag film after etching;

[0045] Fig.14 is a SEM image of a high-precision anode of a silicon-based OLED display device in an embodiment;

[0046] Fig.15 This is a SEM image of a high-precision anode of a silicon-based OLED display device prepared by etching a silver film using a conventional dry etching method. DETAILED DESCRIPTION

[0047] The present invention is described in detail below with reference to the embodiments.

[0048] Example

[0049] A method for preparing a high-precision anode for a silicon-based OLED display device comprises the following steps:

[0050] (1) A silicon substrate with a CMOS driving circuit is placed in a magnetron sputtering coating device to deposit a composite laminate film, wherein the film layer materials are Ti and TiN; Figure 2 As shown;

[0051] (2) The substrate is placed in the magnetron sputtering coating device again to deposit a Ag film layer, where Ag is the anode reflective layer with a thickness of 50-200 nm; Figure 3 As shown; the reflectivity of Ag after coating at different wavelength spectra is as follows Fig.12 As shown, the transmittance in the band sensitive to the naked eye can reach 98%;

[0052] (3) placing the substrate in a chemical vapor deposition device PECVD, and depositing a silicon nitride film and / or a silicon oxide film on the Ag film layer as an anode protective film with a thickness of 100-200 nm to protect the Ag film layer; Figure 4 As shown;

[0053] (4) coating, exposing and developing are performed on the substrate in sequence, and the required photolithography pattern, i.e., the anode pattern, is produced using photoresist with a thickness of 500-1000 nm; Figure 5 As shown;

[0054] (5) Select carbon tetrafluoride as the process gas for etching silicon dielectrics, and etch with nitrogen or argon gas with good vertical etching properties for 70 seconds, with a gas flow rate of 5-50 sccm, to etch away the anode protection film not covered by the photoresist; Figure 6 As shown;

[0055] (6) Stop the introduction of carbon tetrafluoride and introduce methane gas as the etching gas, nitrogen or argon as the carrier gas, and continue etching for 70 seconds. The volume proportion of the alkyl gas is 20-100%, and the gas flow rate is 5-50 sccm. Etch away the Ag film layer without the protection of the anode protection film until the bottom exposes the CMOS substrate; Figure 7 As shown; the SEM image after etching is as follows Fig.13 As shown in the figure, it can be seen that there is less polymer after etching, the surface is smoother, and there is no visible residue in the channel;

[0056] (7) The substrate is cleaned and then rinsed with NMP to completely remove the byproducts and residual photoresist on the sidewalls of the Ag anode pattern. The damage to Ag by this cleaning method is 10-15 angstroms per minute, which can meet the requirements of preparing high-precision Ag anodes; Figure 8 As shown; the cleaning liquid can be selected as DuPont EKC stripping liquid;

[0057] (8) placing the substrate in an ICP dry etching device, introducing carbon tetrafluoride and nitrogen or argon, etching the anode protective film on the front side of the substrate for 70 seconds at a gas flow rate of 5-50 sccm to expose the Ag anode pattern; Fig. 9 As shown;

[0058] (9) placing the substrate in a PECVD device again to deposit a silicon nitride film and / or a silicon oxide film to fill the trenches between the Ag anode patterns and completely cover the Ag anodes, with a thickness of 900-1000 nm; Fig.10 As shown;

[0059] (10) Place the substrate in a chemical mechanical polishing device and use a polishing liquid to perform a flattening treatment to remove the silicon nitride film and / or silicon oxide film until the Ag surface is exposed, and then clean it, such as Fig.11 shown.

[0060] The high-precision anode of the silicon-based OLED display device prepared in this embodiment is as follows Fig.14 As shown in the figure, it can be seen that the size of a single anode can reach 0.75um, and it is actually possible to prepare anodes with higher precision, which can meet the high-precision anode requirements of silicon-based MicroOLED.

[0061] When using conventional dry etching, such as using Cl-based gases—Cl2 and BCl3 to etch the silver film, the surface roughness is very poor after etching, and a large number of particles remain on the surface and PR sidewalls, affecting the reflectivity of the high-precision Ag anode. Fig.15 shown.

[0062] The detailed description of the method for preparing a high-precision anode for a silicon-based OLED display device with reference to the above embodiment is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-precision anode for a silicon-based OLED display device, characterized in that: The anode metal film layer of the high-precision anode of the silicon-based OLED display device is a silver film layer. When etching the silver film layer, alkyl gas is used as etching gas and inert gas is used as carrier gas for dry etching.

2. The preparation method according to claim 1, characterized in that: In the mixed gas of the alkyl gas and the inert gas, the volume proportion of the alkyl gas is 20 to 100%.

3. The preparation method according to claim 1, characterized in that: The alkyl gas is at least one of methane and ethane; the inert gas is at least one of nitrogen and argon.

4. The preparation method according to claim 2, characterized in that: The gas flow rate of the mixed gas of the gas and the inert gas is 5 to 50 sccm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The method for preparing a high-precision anode of a silicon-based OLED display device comprises the following steps: (1) Depositing a composite laminated film of Ti and TiN on the surface of a silicon substrate with CMOS circuit drive; (2) depositing an Ag film on the composite laminated film of Ti and TiN; (3) depositing an anode protective film on the Ag film; (4) coating, exposing, and developing the surface of the anode protective film to prepare an anode pattern; (5) performing dry etching on the anode protection film to etch away the anode protection film not covered by the photoresist; (6) Dry etching the Ag film; (7) placing the silicon substrate in N-methylpyrrolidone for rinsing to remove etching byproducts and photoresist on the side wall of the Ag film; (8) dry etching the anode protective film on the surface of the Ag film to obtain a silicon substrate with the Ag film completely exposed; (9) depositing an anode protection film to fill the trenches between the Ag film patterns and completely cover the Ag film; (10) Remove the anodic protective film on the surface of the Ag film until it leaks out of the surface of the Ag film, and then clean it.

6. The preparation method according to claim, characterized in that: The anode protection film is a silicon oxide film, a silicon nitride film, or a composite laminated film of silicon oxide and silicon nitride.

7. The preparation method according to claim 5, characterized in that: In step (5) and step (8), dry etching is performed using carbon tetrafluoride as etching gas and an inert gas as a carrier gas.

8. The preparation method according to claim 5, characterized in that: The thickness of the Ag film is 50-200 nm.

9. The preparation method according to claim 5, characterized in that: The thickness of the composite laminated film of Ti and TiN is 2-20 nm.

10. The preparation method according to claim 5, characterized in that: In step (6), the etching depth of the Ag film is equal to the thickness of the silver film layer.

Images