Method for improving transmittance of a-Si TFT liquid crystal display

Abstract

The invention relates to a method for improving the transmittance of an a-Si TFT (Thin Film Transistor) liquid crystal display. The method comprises the following steps of: placing a substrate on which a silicon nitride insulating layer is to be deposited into an AKT CVD (Amplitude Kalman Transfer Chemical Vapor Deposition) vacuum cavity; enabling the substrate to be in contact with a heating bearing base, enabling the glass substrate to be uniformly heated, and lifting the substrate to a position which is a first distance away from the upper electrode; n2 is introduced, the pressure of the cavity is controlled, first high-frequency power is output, N2 is ionized, and the surface of the substrate is treated; introducing NH3, SiH4 and N2, controlling the pressure of the cavity, outputting second high-frequency power, ionizing the reaction gas, reacting to generate a silicon nitride film, and depositing the silicon nitride film on the glass substrate; introducing H2, controlling the pressure of the cavity, outputting third high-frequency power, ionizing H2, and treating the surface of the silicon nitride film; and the substrate is transferred out of the vacuum cavity, and the silicon nitride film deposition process is completed. According to the method, under the condition that the defect density and the electrical property of the deposited film are not influenced, the roughness between film layer interfaces is reduced, the light scattering loss is reduced, and the TFT transmittance is improved, so that the transmittance of a liquid crystal display is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal display production, and in particular to a method for improving the transmittance of an a-Si TFT liquid crystal display. Background Art

[0002] The transmittance of a-Si TFT technology LCD is affected by many factors, including TFT transmittance, liquid crystal materials, color filters, module assembly and aperture ratio. The optically transparent film of a-Si TFT 7 mask design has 5 layers: GI (SiNx insulation layer), PV (SiNx insulation layer), BC (ITO conductive layer), CH (SiNx insulation layer), and PE (ITO conductive layer). Figure 1 As shown. Visible light will absorb, reflect, and scatter when passing through each layer of film. The transmittance of a-Si TFT currently produced is sorted out layer by layer. After CH (SiNx insulating layer) covers BC (ITO conductive layer), the transmittance drops suddenly. Therefore, the light scattering effect can be reduced by optimizing the BC-CH film interface to improve the product transmittance. Summary of the invention

[0003] The purpose of the present invention is to provide a method for improving the transmittance of an a-Si TFT liquid crystal display, which can reduce the roughness between film layer interfaces, reduce light scattering losses, and improve TFT transmittance without affecting the density of film defects and electrical properties, thereby improving the transmittance of the liquid crystal display.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: a method for improving the transmittance of an a-Si TFT liquid crystal display, comprising the following steps: Step 1, placing the substrate on which the silicon nitride insulating layer is to be deposited into the AKT CVD vacuum chamber through a vacuum conveying mechanism; Step 2, placing the substrate on which the silicon nitride insulating layer is to be deposited in contact with the heating support base, so that the glass substrate is heated evenly, and lifting the substrate to a first distance from the upper electrode; Step 3, introducing a first flow rate of N2, controlling the chamber pressure at a first pressure through a pressure regulating valve, outputting a first high frequency power, ionizing the N2, and processing the substrate surface; Step 4, introducing a second flow rate of NH3, a third flow rate of SiH4, and a fourth flow rate of N2, controlling the chamber pressure at a second pressure through a pressure regulating valve, outputting a second high frequency power, ionizing the reaction gas, and reacting to generate a silicon nitride film that is deposited on the glass substrate; Step 5, introducing H2 at a fifth flow rate, controlling the cavity pressure at a third pressure through a pressure regulating valve, outputting a third high frequency power, ionizing H2, and treating the surface of the silicon nitride film; Step 6: After the deposition is completed, the substrate is transferred out of the vacuum chamber to complete the silicon nitride film deposition process.

[0005] Furthermore, in step 2, the substrate is lifted to a distance of 1000 mils from the upper electrode.

[0006] Furthermore, in step 3, 10000 sccm of N2 is introduced, the chamber pressure is controlled at 1500 mtorr through a pressure regulating valve, and 1500 W of high-frequency power is output to ionize N2 and process the substrate surface.

[0007] Furthermore, in step 4, 5400 sccm of NH3, 2400 sccm of SiH4, and 160 sccm of N2 are introduced, the chamber pressure is controlled at 1080 mtorr through a pressure regulating valve, and 11000 W of high-frequency power is output to ionize the reaction gas, and the reaction generates a silicon nitride film which is deposited on the glass substrate.

[0008] Furthermore, in step 5, 15000 sccm of H2 is introduced, the chamber pressure is controlled at 1500 mtorr through a pressure regulating valve, and 3000 W of high-frequency power is output to ionize H2 and treat the surface of the silicon nitride film.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a low bombardment force plasma treatment technology before SiNx film formation to improve the transmittance of a-Si TFT liquid crystal display. This technology can reduce the roughness of the film matching, reduce light scattering loss, and improve the TFT transmittance without affecting the density and electrical properties of the deposited film defects, thereby improving the transmittance of the liquid crystal display and enhancing the product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of a-Si TFT 7 mask in the prior art; Figure 2 is a flow chart of a method implementation of an embodiment of the present invention; Figure 3 This is a comparison diagram of the roughness of the overlapping interface of the film layer without adopting the method and adopting the method detected by using an atomic force scanning microscope in an embodiment of the present invention; Figure 4 is a comparison diagram of defect density of a film layer detected by automatic optical inspection without using the method and with using the method in an embodiment of the present invention; Figure 5 This is a comparison diagram of the electrical properties of a TFT that does not adopt the method and adopts the method, detected by an electrical property detection machine in an embodiment of the present invention; Figure 6 This is a comparison chart of transmittances detected by a transmittance inspection machine without using the method and with using the method in an embodiment of the present invention. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0012] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0013] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0014] The pre-treatment of silicon nitride film is a plasma treatment technology. N2 gas is introduced into the reactor at a process temperature of 210 ℃, and a high-frequency electric field is applied to break the chemical bonds and ionize to form plasma. The high-energy electrons and ions in the plasma collide with the gas molecules, making them highly active. The active reaction gas collides with the substrate surface under the action of the electromagnetic field to treat the substrate surface.

[0015] like Figure 2 As shown, this embodiment provides a method for improving the transmittance of an a-Si TFT liquid crystal display, comprising the following steps: Step 1, placing the substrate on which the silicon nitride insulating layer is to be deposited into the AKT CVD vacuum chamber through a vacuum conveying mechanism; Step 2, placing the substrate on which the silicon nitride insulating layer is to be deposited in contact with the heating support base, so that the glass substrate is heated evenly, and lifting the substrate to a distance of 1000 mils from the upper electrode; Step 3: Introduce N2 at 10,000 sccm, control the chamber pressure at 1,500 mtorr through a pressure regulating valve, output 1,500 W high-frequency power, ionize N2, and process the substrate surface; Step 4: 5400 sccm of NH3, 2400 sccm of SiH4, and 160 sccm of N2 are introduced, and the chamber pressure is controlled at 1080 mtorr through a pressure regulating valve. 11000 W of high frequency power is output to ionize the reaction gas, and the reaction generates a silicon nitride film which is deposited on the glass substrate; Step 5: Introduce H2 at 15000 sccm, control the chamber pressure at 1500 mtorr through a pressure regulating valve, output 3000W high frequency power, ionize H2, and treat the surface of the silicon nitride film; Step 6: After the deposition is completed, the substrate is transferred out of the vacuum chamber to complete the silicon nitride film deposition process.

[0016] Figure 3 This is a comparison of the roughness of the film layer overlap interface detected by atomic force scanning microscopy in this embodiment without using this method and using this method. Figure 3 As shown, the method can reduce the roughness of the overlapping interface of the film layer.

[0017] Figure 4 1 is a comparison chart of the defect density of the film layer detected by automatic optical inspection without using this method and using this method in this embodiment. Figure 4 As shown, there is no abnormality in the defect density of the film layer after adopting this method, which shows that this method does not affect the defect density of the deposition film.

[0018] Figure 5 1 is a comparison diagram of the electrical properties of TFTs that are not tested using this method and are tested using this method using an electrical property tester in this embodiment. Figure 5 As shown, there is no abnormality in the electrical properties of the TFT after sampling using this method, which shows that this method does not affect the electrical properties of the TFT.

[0019] Figure 6 This is a comparison chart of the transmittance of the present embodiment when the transmittance inspection machine is used to inspect the transmittance without using the present method and with using the present method. Figure 6 As shown, the sampling method can improve the TFT transmittance.

[0020] The present invention provides a method for improving the transmittance of an a-Si TFT liquid crystal display. The method can be applied to plasma treatment before the insulating layer of a TFT array process. By adjusting the plasma treatment process parameters, the overlap roughness of the film layer interface is reduced, thereby improving the product transmittance.

[0021] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for improving the transmittance of an a-Si TFT liquid crystal display, characterized in that: The following steps are involved: Step 1, placing the substrate on which the silicon nitride insulating layer is to be deposited into the AKT CVD vacuum chamber through a vacuum conveying mechanism; Step 2, placing the substrate on which the silicon nitride insulating layer is to be deposited in contact with the heating support base, so that the glass substrate is heated evenly, and lifting the substrate to a first distance from the upper electrode; Step 3, introducing a first flow rate of N2, controlling the chamber pressure at a first pressure through a pressure regulating valve, outputting a first high frequency power, ionizing the N2, and processing the substrate surface; Step 4, introducing a second flow rate of NH3, a third flow rate of SiH4, and a fourth flow rate of N2, controlling the chamber pressure at a second pressure through a pressure regulating valve, outputting a second high frequency power, ionizing the reaction gas, and reacting to generate a silicon nitride film that is deposited on the glass substrate; Step 5, introducing H2 at a fifth flow rate, controlling the cavity pressure at a third pressure through a pressure regulating valve, outputting a third high frequency power, ionizing H2, and treating the surface of the silicon nitride film; Step 6: After the deposition is completed, the substrate is transferred out of the vacuum chamber to complete the silicon nitride film deposition process.

2. A method for improving the transmittance of an a-Si TFT liquid crystal display according to claim 1, characterized in that: In step 2, the substrate is lifted to a distance of 1000 mils from the upper electrode.

3. The method for improving the transmittance of an a-Si TFT liquid crystal display according to claim 1, characterized in that: In step 3, 10,000 sccm of N2 is introduced, the chamber pressure is controlled at 1,500 mtorr through a pressure regulating valve, and 1,500 W of high-frequency power is output to ionize N2 and process the substrate surface.

4. The method for improving the transmittance of an a-Si TFT liquid crystal display according to claim 1, characterized in that: In step 4, 5400 sccm of NH3, 2400 sccm of SiH4, and 20160 sccm of N2 are introduced, the chamber pressure is controlled at 1080 mtorr through a pressure regulating valve, and 11000 W of high-frequency power is output to ionize the reaction gas, and the reaction generates a silicon nitride film that is deposited on the glass substrate.

5. The method for improving the transmittance of an a-Si TFT liquid crystal display according to claim 1, characterized in that: In step 5, 15000 sccm of H2 is introduced, the chamber pressure is controlled at 1500 mtorr through a pressure regulating valve, and 3000 W of high-frequency power is output to ionize H2 and treat the surface of the silicon nitride film.

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