A method of crystal implantation for display thin film

Abstract

The application provides a kind of display film crystalline injection process method, belongs to thin film crystalline injection technical field, method includes: S1, preparation stress buffer and crystallization control adjuvant, its raw material includes vinyltriethoxysilane, polyether modified polysiloxane surfactant and propylene glycol methyl ether acetate etc.;S2, indium nitrate, gallium nitrate, zinc acetate and adjuvant are mixed, and preparation base composite precursor solution A;S3, solution A is spin-coated into film, and gradient drying and pre-solidification are carried out to obtain pre-solidification film;S4, the impregnation liquid B obtained by diluting with adjuvant is used to carry out liquid phase assisted impregnation on pre-solidification film, and low oxygen atmosphere is carried out in low temperature activation gradient annealing;S5, in inert atmosphere, carry out rapid thermal annealing;The application realizes high-quality crystallization of film at lower temperature by adjuvant and synergistic annealing process, reduces the internal stress of film, and the prepared display film has excellent electrical performance uniformity, high light transmittance and low residual stress.

Description

Technical Field

[0001] This invention relates to the field of thin film crystal implantation technology, and in particular to a crystal implantation process method for display thin films. Background Technology

[0002] Metal oxide semiconductor thin films, such as indium gallium zinc oxide (IGZO) films, have become core materials for the active layers of thin-film transistors (TFTs) in high-performance display devices, particularly active-matrix organic light-emitting diodes (AMOLEDs) and high-end liquid crystal displays (LCDs), due to their high carrier mobility, high uniformity, low leakage current, and good visible light transmittance. Compared with vacuum deposition techniques (such as magnetron sputtering), solution-based fabrication techniques (such as sol-gel methods and metal-organic compound decomposition methods) have significant advantages, including low equipment cost, high material utilization, ease of large-area and patterned deposition, and precise component control, and are considered an important technological route for future low-cost, large-size display panel manufacturing. However, the preparation of high-quality metal oxide semiconductor thin films, especially crystalline films that meet display driving requirements, still faces significant challenges. First, the transformation from solution precursors to dense, highly crystalline oxide semiconductor thin films typically requires high annealing temperatures to thoroughly decompose organic components, eliminate defects, and promote grain growth. This temperature requirement far exceeds the tolerance limits of many flexible polymer substrates, severely restricting the application of solution methods in the field of flexible electronics. Even on high-temperature resistant rigid substrates, rapid high-temperature processing can easily introduce enormous thermal stress into the thin film, leading to cracking, warping, or decreased adhesion to the substrate, severely impacting device reliability and yield. Secondly, at relatively low annealing temperatures, the crystallization process of the thin film is often insufficient, easily forming amorphous or microcrystalline structures with high internal defect state density. This results in low carrier mobility, poor electrical stability, and severe threshold voltage drift, failing to meet the requirements of high-performance TFTs. Simultaneously, solvent evaporation, precursor decomposition and shrinkage, and the mismatch in thermal expansion coefficients between the thin film and the substrate during solution film formation all generate complex stresses within the film. These residual stresses are a key factor causing uneven film performance, discrete device characteristics, and even failure. Existing technologies add various additives to the precursor solution to lower the crystallization temperature or improve film quality, employ multilayer deposition structures to release stress, or design complex gradient annealing and rapid thermal annealing (RTA) processes. However, these methods often only partially solve the problem or introduce new process complexities. For example, conventional additives may remain in the film, becoming impurity centers and degrading electrical performance; multilayer structures increase the risk of process steps and interface defects; and simple annealing process adjustments often fail to simultaneously achieve multiple interrelated or even contradictory goals, such as the low-temperature decomposition of organic matter, the effective formation and growth of crystal nuclei, and the effective relaxation of internal stress. In particular, how to achieve precise injection and induction of the thin film crystallization process without significantly increasing the process temperature, while simultaneously achieving active buffering and control of internal stress, remains a pressing technical challenge in this field. Therefore, developing a novel crystal injection process for display thin films has become an urgent need for the industry. Summary of the Invention

[0003] The purpose of this invention is to provide a crystal implantation process for display thin films, addressing the problems of existing solutions-based metal oxide semiconductor thin film preparation methods. These problems include excessively high annealing temperatures required for high-quality crystallization, incompatibility with flexible substrate processes, insufficient crystallization and poor electrical properties at relatively low temperatures, and high internal stress during the process, leading to defects and performance inhomogeneity. These issues collectively result in thin films that cannot simultaneously meet the stringent requirements of high-performance, high-reliability display devices for low-temperature processing, excellent electrical properties, and good mechanical stability. The specific technical solution of this invention is as follows: This invention provides a crystal implantation process for display thin films, the method comprising the following steps: S1. Preparation of stress buffering and crystallization regulating agents; S2. Preparation of basic composite precursor solution A. The raw materials for preparing basic composite precursor solution A include, by weight, 10.5-14 parts indium nitrate pentahydrate, 3.7-4.5 parts gallium nitrate hexahydrate, 6.2-6.8 parts zinc acetate dihydrate, 64-70 parts propylene glycol methyl ether acetate, 2.0-2.5 parts acetylacetone, 15-20 parts stress buffer and crystallization regulating agent prepared in step S1, and 0.2-0.5 parts polyether modified polysiloxane surfactant. S3. Thin film deposition, gradient drying and pre-curing: The basic composite precursor solution A prepared in step S2 is spin-coated onto the substrate, and then the wet film is gradient dried and pre-cured on a precision temperature-controlled hot plate to obtain a pre-cured thin film sample. S4. Liquid-phase assisted impregnation and low-temperature activation annealing: The stress buffer and crystallization regulating agent prepared in step S1 is diluted with propylene glycol methyl ether acetate to obtain impregnation solution B. This solution is then coated onto the surface of the thin film sample obtained in step S3 and treated. Finally, the first gradient annealing is performed in a low-oxygen atmosphere. S5. Crystallization and Stabilization Annealing: The sample treated in step S4 is subjected to a second rapid thermal annealing in an inert gas atmosphere to complete crystal implantation.

[0004] Furthermore, the raw materials for preparing the stress buffer and crystallization regulating agent include, by weight, 8-12.5 parts vinyltriethoxysilane, 2.2-2.8 parts ammonium nitrate, 3.5-4.2 parts urea, 3.5-6 parts zinc oxide nanocrystals, 2.2-3 parts acetylacetone, 0.6-0.8 parts polyether-modified polysiloxane surfactant, and 70.7-80 parts propylene glycol methyl ether acetate.

[0005] Further, step S1 specifically includes: under nitrogen protection, adding 55.7-80 parts of propylene glycol methyl ether acetate to the reaction vessel, stirring at 400 rpm, adding vinyltriethoxysilane and acetylacetone; increasing the stirring speed to 600 rpm, raising the temperature of the reaction system to 45-50℃, and stirring for 80-90 minutes; dissolving ammonium nitrate and urea separately in deionized water, and then adding them dropwise to the reaction system together with the polyether-modified polysiloxane surfactant at a rate of 1 drop per second for 100-120 minutes; adding a zinc oxide nanocrystal dilution solution pre-dispersed with propylene glycol methyl ether acetate, increasing the stirring speed to 800 rpm, raising the temperature to 60-65℃, and stirring for 150-180 minutes; finally, cooling the reaction solution to below 30℃, and filtering it through a 0.1-micron filter cartridge to obtain a stress buffer and crystallization regulating agent.

[0006] Further, step S2 specifically includes: in a clean room with constant temperature and humidity of 23°C and 35% relative humidity, propylene glycol methyl ether acetate solvent is added to a reaction flask and stirred at 300 rpm. Indium nitrate pentahydrate, gallium nitrate hexahydrate, and zinc acetate dihydrate are added sequentially. The stirring rate is increased to 500 rpm, the system temperature is maintained at 25°C, acetylacetone is added dropwise at a uniform rate until complete, and stirring is continued for 100-120 minutes to form a metal complex base solution. The stress buffer and crystallization regulator prepared in step S1 is added, the stirring rate is increased to 800 rpm, the temperature is raised to 38-40°C, and stirring is carried out for 150-180 minutes. Then, polyether-modified polysiloxane surfactant is added, the stirring rate is adjusted to 400 rpm, and the mixture is aged at 38-40°C for 40-60 minutes. Finally, the mixture is filtered through a 0.2-micron filter membrane to obtain the basic composite precursor solution A.

[0007] Furthermore, in step S3, the spin coating parameters are: 100 revolutions per second. 2 The acceleration increases the substrate rotation speed to 800 rpm and holds it for 10 seconds, then decreases it to 500 rpm. 2 The acceleration reaches 3000 rpm and is maintained for 20-30 seconds; Gradient drying and pre-curing consists of three stages: the first stage is to stand at 80-90℃ for 60-90 seconds; the second stage is to heat up to 120-130℃ and hold for 120-180 seconds; the third stage is to heat up to 210-220℃ and hold for 250-300 seconds.

[0008] Further, in step S4, the impregnation solution B is obtained by diluting the stress buffer and crystallization regulating agent prepared in step S1 with propylene glycol methyl ether acetate to 50%-60% of its original viscosity; the coating method is spraying, and the coating amount is 2.5-3.0 μL per square centimeter of film surface; after coating, the sample is placed in a sealed chamber filled with saturated propylene glycol methyl ether acetate vapor at 25°C and left to stand for 80-120 seconds.

[0009] Further, in step S4, the first gradient annealing is carried out in a tubular annealing furnace, specifically including: purging with high-purity nitrogen for 5-10 minutes, then switching the atmosphere to a nitrogen-oxygen mixture with an oxygen volume fraction of 1%-2%; raising the temperature from room temperature to 265-280℃ at a rate of 2-3℃ / min, and holding at 265-280℃ for 20-40 minutes; and cooling down to below 150℃ at a rate of 2-3℃ / min.

[0010] Furthermore, in step S5, the second rapid thermal annealing is carried out in a rapid thermal annealing equipment under the following conditions: the sample surface temperature is raised to 365-380℃ at a heating rate of 20-30℃ / second under a pure nitrogen atmosphere, and held at 365-380℃ for 3-8 minutes, and then naturally cooled to room temperature.

[0011] Furthermore, before adding the zinc oxide nanocrystal diluent in step S1, the pretreatment method for the zinc oxide nanocrystals is as follows: the zinc oxide nanocrystals are mixed and dispersed with propylene glycol methyl ether acetate to obtain the zinc oxide nanocrystal diluent.

[0012] Further, zinc oxide nanocrystals were mixed with propylene glycol methyl ether acetate and dispersed by high-speed shearing at 3000 rpm for 10-15 minutes to obtain a diluted zinc oxide nanocrystal solution.

[0013] The beneficial effects of this invention are as follows: The crystal implantation process for display films provided by this invention improves the overall performance of the film by synergistically compounding metal salt precursors, solvents, acetylacetone, surfactants, and stress buffers and crystallization control agents, combined with a two-step process (i.e., firstly, partially introducing the additives into the base solution for premixing, and then, after the film pre-curing, supplementing the remaining additives through liquid-phase assisted impregnation and performing low-temperature activation annealing). Experimental data show that Example 1 achieved the best results: its carrier mobility was increased, resistivity was reduced, surface roughness was small, film stress was controlled at the optimal level of -125 MPa, and light transmittance was good. In contrast, the performance of the comparative examples lacking key components or changing the process deteriorated, fully demonstrating that the components and step-by-step processes produced a synergistic effect, jointly solving the technical problems of poor film crystal quality, low electrical performance, and high internal stress in traditional processes, achieving an ideal balance between high mobility, low resistivity, excellent flatness, and low stress in the film. Specifically, acetylacetone, as a strong chelating agent, fully complexes with metal ions such as indium nitrate and gallium nitrate, effectively reducing the activity of the precursor solution and inhibiting the premature eruption of undesirable crystal nuclei in the early stage of film formation, laying the foundation for the uniform growth of subsequent crystals. Secondly, zinc oxide nanocrystals act as efficient heterogeneous nucleation centers in the film, inducing the metal oxide matrix to grow directionally around them, thereby significantly refining the grain size and reducing defect states at grain boundaries, which is the fundamental reason for the significant improvement in carrier mobility. Thirdly, the thermally responsive synergistic nitrogen source composed of ammonium nitrate and urea decomposes under heat during the low-temperature annealing stage after liquid-phase assisted impregnation and releases active nitrogen-containing species. These species diffuse into the interstitial spaces, effectively compensating for lattice defects and optimizing the carrier concentration. Vinyltriethoxysilane undergoes a hydrolysis-condensation reaction in the system to form a flexible three-dimensional network structure. This structure not only physically blocks excessive grain growth but also acts as a buffer to absorb and release the internal stress generated during the shrinkage of the film during heat treatment. In addition, the two-step process design is crucial. The first step, premixing, ensures the uniformity of the substrate film formation. The second step, liquid-assisted impregnation after pre-curing, utilizes capillary action to fully wet the micropores on the film surface and penetrate into the interior. Combined with the subsequent low-temperature activation annealing, the dopant distribution becomes deeper and more uniform, avoiding the surface enrichment or agglomeration that may occur in the traditional one-step process. Ultimately, multiple objectives are achieved, including densification of the film microstructure, optimization of electrical properties, and stabilization of stress state. Detailed Implementation

[0014] The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] The polyether-modified polysiloxane surfactant involved in this invention is Xinno® WE-D545 from Anhui Jiazhi Xinno Chemical Co., Ltd., and the zinc oxide nanocrystal sol is Brofos-ZnO-F10 from Bohuas Nanotechnology (Ningbo) Co., Ltd., with a particle size of 10-20nm and a concentration of 15%.

[0016] Example 1 This embodiment provides a crystal implantation process for display thin films, including a composite precursor solution. The raw materials for preparing the composite precursor solution include, by weight, 14 parts indium nitrate pentahydrate, 4.5 parts gallium nitrate hexahydrate, 6.8 parts zinc acetate dihydrate, 68 parts propylene glycol methyl ether acetate, 2.5 parts acetylacetone, 20 parts stress buffering and crystallization regulating agent, and 0.5 parts polyether modified polysiloxane surfactant.

[0017] The raw materials for preparing the stress buffer and crystallization regulating agent include, by weight: 12.5 parts vinyltriethoxysilane, 2.8 parts ammonium nitrate, 4.2 parts urea, 6 parts zinc oxide nanocrystal sol, 3 parts acetylacetone, 0.8 parts polyether modified polysiloxane surfactant, and 70.7 parts propylene glycol methyl ether acetate.

[0018] This embodiment also provides a crystal implantation process for display thin films, the method comprising the following steps by weight: Step 1: Preparation of stress buffer and crystallization regulating agent: Under nitrogen protection, add 55.7 parts of propylene glycol methyl ether acetate and stir at 400 rpm. Add 12.5 parts of vinyltriethoxysilane and 3.0 parts of acetylacetone. After about 10 minutes, increase the stirring speed to 600 rpm. Raise the temperature of the reaction system to 50°C at a uniform rate through a jacketed oil bath and stir for 90 minutes. Dissolve 2.8 parts of ammonium nitrate in 5 parts of deionized water and dissolve 4.2 parts of urea in another 5 parts of deionized water. Add the two aqueous solutions and 0.8 parts of polyether modified polysiloxane surfactant dropwise to the reaction vessel at a rate of 1 drop per second for 120 minutes through two constant pressure dropping funnels.

[0019] 6.0 parts of zinc oxide nanocrystals (average particle size 5 nm) diluted solution, which was prepared by high-speed shear dispersion of 15 parts of propylene glycol methyl ether acetate at 3000 rpm for 15 minutes, were added to the reactor. The stirring rate was increased to 800 rpm, the temperature was raised to 65°C, and the mixture was stirred for 180 minutes.

[0020] The reaction solution was naturally cooled to below 30°C under nitrogen protection. During the cooling process, the stirring rate was reduced to 200 revolutions per minute. The solution was then pressure filtered using a 0.1-micron polytetrafluoroethylene filter at a pressure of 0.3 MPa to obtain a stress buffer and crystallization regulator, which was stored in a brown glass bottle for later use.

[0021] Step 2: Preparation of the basic composite precursor solution: In a clean room with constant temperature and humidity of 23℃ and 35% relative humidity, 68.0 parts of propylene glycol methyl ether acetate solvent were added to a 2-liter jacketed glass reaction flask. The anchor stirrer was started and the speed was set to 300 rpm. 14.0 parts of indium nitrate pentahydrate, 4.5 parts of gallium nitrate hexahydrate, and 6.8 parts of zinc acetate dihydrate were added, with each raw material added at 2-minute intervals. The stirring speed was increased to 500 rpm, and the temperature was maintained by circulating 25℃ constant temperature water through the jacket. 2.5 parts of acetylacetone were added dropwise to the reaction flask at a rate of 5 ml per minute through a constant pressure dropping funnel over a period of 30 minutes. The mixture was stirred at 500 rpm for 120 minutes at 25℃ to form the metal complex base solution.

[0022] Take 10 portions of the stress buffer and crystallization regulator prepared in step 1 and add them to the metal complex base liquid. Increase the stirring speed to 800 revolutions per minute and raise the reaction temperature to 40°C through an oil bath. Stir for 180 minutes.

[0023] Add 0.5 parts of polyether-modified polysiloxane surfactant, adjust the stirring speed to 400 rpm, and continue aging at 40°C for 60 minutes. After the reaction is complete, filter the resulting composite sol through a 0.2-micron polytetrafluoroethylene filter membrane at a pressure of 0.3 MPa to obtain the basic composite precursor solution A.

[0024] Step 3, Thin Film Deposition, Gradient Drying and Pre-curing: Fix the cleaned substrate, which has been treated with UV ozone for 10 minutes, on a spin coater. Accelerate the substrate from 100 rpm to 800 rpm and hold for 10 seconds. Then accelerate it from 500 rpm to 3000 rpm and hold for 30 seconds. Spin coat the basic composite precursor solution A prepared in Step 2 into a film.

[0025] The spin-coated wet film was transferred to a precision temperature-controlled hot plate for gradient drying and pre-curing: in the first stage, it was left to stand at 80°C for 90 seconds; in the second stage, the temperature was increased to 120°C and held for 180 seconds; in the third stage, the temperature was increased to 220°C and held for 300 seconds to allow the film to be initially cured, thus obtaining a pre-cured film sample.

[0026] Step 4, Liquid-phase assisted impregnation and low-temperature activation annealing: Place the pre-cured film sample from Step 3 horizontally in a dedicated impregnation apparatus. Take 10 parts of the stress buffer and crystallization regulating agent prepared in Step 1, and dilute it with propylene glycol methyl ether acetate to 50% of its original viscosity to obtain impregnation solution B.

[0027] The impregnation solution B was uniformly sprayed onto the film surface at a rate of 2.5 μL per square centimeter. The sample was then transferred to a sealed chamber filled with saturated propylene glycol methyl ether acetate vapor at 25°C and allowed to stand for 120 seconds to allow the impregnation solution B to fully wet and penetrate the film surface.

[0028] Remove the sample and place it in a tube annealing furnace. Purge with high-purity nitrogen at a flow rate of 2 liters per minute for 10 minutes. Switch the atmosphere to a nitrogen-oxygen mixture with an oxygen volume fraction of 1%, maintaining a total flow rate of 2 liters per minute. Increase the furnace temperature from room temperature to 280°C at a rate of 2°C per minute, and hold at 280°C for 40 minutes. Cool the furnace temperature to below 150°C at a rate of 2°C per minute, and allow it to cool naturally to room temperature.

[0029] Step 5, Crystallization and Stabilization Annealing: Transfer the sample to a rapid thermal annealing device, raise the sample surface temperature to 380°C at a heating rate of 30°C per second under a pure nitrogen atmosphere, and maintain the temperature at 380°C for 8 minutes. Allow the sample to cool naturally to room temperature under a nitrogen atmosphere to complete the crystal implantation of the display film.

[0030] Example 2 This embodiment provides a crystal implantation process for display thin films, including a composite precursor solution. The raw materials for preparing the composite precursor solution include, by weight, 12 parts indium nitrate pentahydrate, 4.1 parts gallium nitrate hexahydrate, 6.5 parts zinc acetate dihydrate, 64 parts propylene glycol methyl ether acetate, 2.2 parts acetylacetone, 17 parts stress buffering and crystallization regulating agent, and 0.3 parts polyether modified polysiloxane surfactant.

[0031] The raw materials for preparing the stress buffer and crystallization regulating agent include, by weight: 10 parts vinyltriethoxysilane, 2.5 parts ammonium nitrate, 3.8 parts urea, 4.5 parts zinc oxide nanocrystal sol, 2.5 parts acetylacetone, 0.7 parts polyether-modified polysiloxane surfactant, and 76 parts propylene glycol methyl ether acetate.

[0032] This embodiment also provides a crystal implantation process for display thin films, the method comprising the following steps by weight: Step 1: Preparation of stress buffer and crystallization regulating agent: Under nitrogen protection, add 76 parts of propylene glycol methyl ether acetate and stir at 400 rpm. Add 10 parts of vinyltriethoxysilane and 2.5 parts of acetylacetone. After about 10 minutes, increase the stirring speed to 600 rpm and raise the temperature of the reaction system to 48°C at a uniform rate through a jacketed oil bath. Stir for 85 minutes. Dissolve 2.5 parts of ammonium nitrate in 5 parts of deionized water and dissolve 3.8 parts of urea in another 5 parts of deionized water. Through two constant pressure dropping funnels, add the two aqueous solutions and 0.7 parts of polyether modified polysiloxane surfactant dropwise to the reaction vessel at a rate of 1 drop per second for 110 minutes.

[0033] Add 4.5 parts of zinc oxide nanocrystal dilution solution, which was prepared by high-speed shear dispersion of 12 parts of propylene glycol methyl ether acetate at 3000 rpm for 12 minutes, to the reactor. Increase the stirring speed to 800 rpm, raise the temperature to 63°C, and stir for 160 minutes.

[0034] The reaction solution was naturally cooled to below 30°C under nitrogen protection. During the cooling process, the stirring rate was reduced to 200 revolutions per minute. The solution was then pressure filtered using a 0.1-micron polytetrafluoroethylene filter at a pressure of 0.3 MPa to obtain a stress buffer and crystallization regulator, which was stored in a brown glass bottle for later use.

[0035] Step 2: Preparation of the basic composite precursor solution: In a clean room with constant temperature and humidity of 23℃ and 35% relative humidity, 64 parts of propylene glycol methyl ether acetate solvent were added to a 2-liter jacketed glass reaction flask. The anchor-type stirrer was started and the speed was set to 300 rpm. 12 parts of indium nitrate pentahydrate, 4.1 parts of gallium nitrate hexahydrate, and 6.5 parts of zinc acetate dihydrate were added sequentially, with a 2-minute interval between each raw material. The stirring speed was increased to 500 rpm, and the temperature was maintained by circulating 25℃ constant temperature water through the jacket. 2.2 parts of acetylacetone were added dropwise to the reaction flask at a rate of 5 ml per minute through a constant pressure dropping funnel over a period of 30 minutes. The mixture was then stirred at 500 rpm for 110 minutes at 25℃ to form the metal complex base solution.

[0036] Take 8.5 parts of the stress buffer and crystallization regulator prepared in step 1 and add them to the metal complex base liquid. Increase the stirring speed to 800 rpm and raise the reaction temperature to 40°C through an oil bath. Stir for 170 minutes.

[0037] Add 0.3 parts of polyether-modified polysiloxane surfactant, adjust the stirring speed to 400 rpm, and continue aging at 40°C for 50 minutes. After the reaction is complete, filter the resulting composite sol through a 0.2-micron polytetrafluoroethylene filter membrane at a pressure of 0.3 MPa to obtain the basic composite precursor solution A.

[0038] Step 3, Thin Film Deposition, Gradient Drying and Pre-curing: Fix the cleaned substrate, which has been treated with UV ozone for 10 minutes, on a spin coater. Accelerate the substrate from 100 rpm to 800 rpm and hold for 10 seconds. Then accelerate it from 500 rpm to 3000 rpm and hold for 25 seconds. Spin coat the basic composite precursor solution A prepared in Step 2 into a film.

[0039] The spin-coated wet film was transferred to a precision temperature-controlled hot plate for gradient drying and pre-curing: in the first stage, it was left to stand at 85°C for 80 seconds; in the second stage, the temperature was increased to 125°C and held for 150 seconds; in the third stage, the temperature was increased to 215°C and held for 280 seconds to allow the film to be initially cured, thus obtaining a pre-cured film sample.

[0040] Step 4, Liquid-phase assisted impregnation and low-temperature activation annealing: The pre-cured film sample from Step 3 is placed horizontally in a dedicated impregnation apparatus. Take 8.5 parts of the stress buffer and crystallization regulating agent prepared in Step 1, and dilute it with propylene glycol methyl ether acetate to 55% of its original viscosity to obtain impregnation solution B.

[0041] The impregnation solution B was uniformly sprayed onto the film surface at a rate of 2.8 μL per square centimeter. The sample was then transferred to a sealed chamber filled with saturated propylene glycol methyl ether acetate vapor at 25°C and allowed to stand for 100 seconds to allow the impregnation solution B to fully wet and penetrate the film surface.

[0042] Remove the sample and place it in a tube annealing furnace. Purge with high-purity nitrogen at a flow rate of 2 liters per minute for 8 minutes. Switch the atmosphere to a nitrogen-oxygen mixture with an oxygen volume fraction of 1%, maintaining a total flow rate of 2 liters per minute. Increase the furnace temperature from room temperature to 275°C at a heating rate of 2.5°C per minute, and hold at 275°C for 30 minutes. Then, cool the furnace temperature to below 150°C at a rate of 2.5°C per minute, and allow it to cool naturally to room temperature.

[0043] Step 5, Crystallization and Stabilization Annealing: Transfer the sample to a rapid thermal annealing device, raise the sample surface temperature to 375°C at a heating rate of 25°C per second under a pure nitrogen atmosphere, and maintain it at 375°C for 5 minutes. Then, allow it to cool naturally to room temperature under a nitrogen atmosphere to complete the crystal implantation of the display film.

[0044] Example 3 This embodiment provides a crystal implantation process for display thin films, including a composite precursor solution. The raw materials for preparing the composite precursor solution include, by weight, 10.5 parts indium nitrate pentahydrate, 3.7 parts gallium nitrate hexahydrate, 6.2 parts zinc acetate dihydrate, 70 parts propylene glycol methyl ether acetate, 2.0 parts acetylacetone, 15 parts stress buffering and crystallization regulating agent, and 0.2 parts polyether modified polysiloxane surfactant.

[0045] The raw materials for preparing the stress buffer and crystallization regulating agent include, by weight: 8 parts vinyltriethoxysilane, 2.2 parts ammonium nitrate, 3.5 parts urea, 3.5 parts zinc oxide nanocrystal sol, 2.2 parts acetylacetone, 0.6 parts polyether-modified polysiloxane surfactant, and 80 parts propylene glycol methyl ether acetate.

[0046] This embodiment also provides a crystal implantation process for display thin films, the method comprising the following steps by weight: Step 1: Preparation of stress buffer and crystallization regulating agent: Under nitrogen protection, add 80 parts of propylene glycol methyl ether acetate and stir at 400 rpm. Add 8 parts of vinyltriethoxysilane and 2.2 parts of acetylacetone. After about 10 minutes, increase the stirring speed to 600 rpm. Raise the temperature of the reaction system to 45°C at a uniform rate through a jacketed oil bath and stir for 80 minutes. Dissolve 2.2 parts of ammonium nitrate in 5 parts of deionized water and dissolve 3.5 parts of urea in another 5 parts of deionized water. Through two constant pressure dropping funnels, add the two aqueous solutions and 0.6 parts of polyether modified polysiloxane surfactant dropwise to the reaction vessel at a rate of 1 drop per second for 100 minutes.

[0047] Add 3.5 parts of zinc oxide nanocrystal dilution solution, which was prepared by high-speed shear dispersion of 10 parts of propylene glycol methyl ether acetate at 3000 rpm for 10 minutes, to the reaction vessel. Increase the stirring speed to 800 rpm, raise the temperature to 60°C, and stir for 150 minutes.

[0048] The reaction solution was naturally cooled to below 30°C under nitrogen protection. During the cooling process, the stirring rate was reduced to 200 revolutions per minute. The solution was then pressure filtered using a 0.1-micron polytetrafluoroethylene filter at a pressure of 0.3 MPa to obtain a stress buffer and crystallization regulator, which was stored in a brown glass bottle for later use.

[0049] Step 2: Preparation of the basic composite precursor solution: In a clean room with constant temperature and humidity of 23℃ and 35% relative humidity, 70 parts of propylene glycol methyl ether acetate solvent were added to a 2-liter jacketed glass reaction flask. The anchor stirrer was started and the speed was set to 300 rpm. 10.5 parts of indium nitrate pentahydrate, 3.7 parts of gallium nitrate hexahydrate, and 6.2 parts of zinc acetate dihydrate were added sequentially, with a 2-minute interval between each raw material. The stirring speed was increased to 500 rpm, and the temperature was maintained by circulating 25℃ constant temperature water through the jacket. 2.0 parts of acetylacetone were added dropwise to the reaction flask at a rate of 5 ml per minute using a constant pressure dropping funnel. The reaction time was 30 minutes. The mixture was stirred at 500 rpm for 100 minutes at 25℃ to form the metal complex base solution.

[0050] Take 7.5 parts of the stress buffer and crystallization regulator prepared in step 1 and add it to the metal complex base liquid. Increase the stirring speed to 800 revolutions per minute and raise the reaction temperature to 38°C through an oil bath. Stir for 150 minutes.

[0051] Add 0.2 parts of polyether-modified polysiloxane surfactant, adjust the stirring speed to 400 rpm, and continue aging at 38°C for 40 minutes. After the reaction is complete, filter the resulting composite sol through a 0.2-micron polytetrafluoroethylene filter membrane at a pressure of 0.3 MPa to obtain the basic composite precursor solution A.

[0052] Step 3, Thin Film Deposition, Gradient Drying and Pre-curing: Fix the cleaned substrate, which has been treated with UV ozone for 10 minutes, on a spin coater. Accelerate the substrate from 100 rpm to 800 rpm and hold for 10 seconds. Then accelerate it from 500 rpm to 3000 rpm and hold for 20 seconds. Spin coat the basic composite precursor solution A prepared in Step 2 into a film.

[0053] The spin-coated wet film was transferred to a precision temperature-controlled hot plate for gradient drying and pre-curing: in the first stage, it was left to stand at 90°C for 60 seconds; in the second stage, the temperature was increased to 130°C and held for 120 seconds; in the third stage, the temperature was increased to 210°C and held for 250 seconds to allow the film to be initially cured, thus obtaining a pre-cured film sample.

[0054] Step 4, Liquid-phase assisted impregnation and low-temperature activation annealing: The pre-cured film sample from Step 3 is placed horizontally in a dedicated impregnation apparatus. Take 7.5 parts of the stress buffer and crystallization regulating agent prepared in Step 1, and dilute it with propylene glycol methyl ether acetate to 60% of its original viscosity to obtain impregnation solution B.

[0055] The impregnation solution B was uniformly sprayed onto the film surface at a rate of 3.0 μL per square centimeter. The sample was then transferred to a sealed chamber filled with saturated propylene glycol methyl ether acetate vapor at 25°C and allowed to stand for 80 seconds to allow the impregnation solution B to fully wet and penetrate the film surface.

[0056] Remove the sample and place it in a tube annealing furnace. Purge with high-purity nitrogen at a flow rate of 2 liters per minute for 5 minutes. Switch the atmosphere to a nitrogen-oxygen mixture with an oxygen volume fraction of 2%, maintaining a total flow rate of 2 liters per minute. Increase the furnace temperature from room temperature to 265°C at a rate of 3°C per minute, and hold at 265°C for 20 minutes. Cool the furnace temperature to below 150°C at a rate of 3°C per minute, and allow it to cool naturally to room temperature.

[0057] Step 5, Crystallization and Stabilization Annealing: Transfer the sample to a rapid thermal annealing device, raise the sample surface temperature to 365°C at a heating rate of 20°C per second under a pure nitrogen atmosphere, and maintain it at 365°C for 3 minutes. Then, allow it to cool naturally to room temperature under a nitrogen atmosphere to complete the crystal implantation of the display film.

[0058] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 lacks stress buffer and crystallization regulation agent, while the rest is the same as Example 1.

[0059] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 lacks vinyltriethoxysilane in the preparation of stress buffer and crystallization control agent; otherwise, it is the same as Example 1.

[0060] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 lacks ammonium nitrate when preparing stress buffer and crystallization control agent; otherwise, it is the same as Example 1.

[0061] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 lacks urea when preparing stress buffer and crystallization regulation aids; otherwise, it is the same as Example 1.

[0062] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 lacks zinc oxide nanocrystal sol in the preparation of stress buffer and crystallization regulation aid; otherwise, it is the same as Example 1.

[0063] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that when preparing the basic composite precursor solution in step 2, all 20 parts of stress buffer and crystallization regulating agent were added. The rest of the contents are the same as those in Example 1.

[0064] Performance testing Electrical, optical, and thin film stress tests were conducted on the examples and comparative examples. The specific methods are as follows: Electrical performance testing was performed using a Technica HMS-3000 Hall effect testing system (Japan). At room temperature and a magnetic field strength of 0.55 T, the Van der Pauw method was used to measure the carrier concentration (n), Hall mobility (μ), and resistivity (ρ) of the thin film. Optical performance testing was performed using a Shimadzu UV-3600 Plus UV-Vis-NIR spectrophotometer (Japan). The transmittance (T) of the thin film in the visible light band (380-780 nm) was measured, and the transmittance value at 550 nm was reported. The optical band gap (Eg) was calculated using the Tauc plot method. A KLA-Tencor Flexus F-2320 thin film stress measurement system (USA) was used. By measuring the change in the radius of curvature of the silicon wafer (100 crystal orientation, thickness 525±25 μm) before and after film deposition, the average stress (σ) of the thin film was calculated according to the Stoney formula. The results are shown in Table 1.

[0065] Table 1: Performance Test Results of Examples and Comparative Examples As shown in Table 1, Examples 1-3 achieved a comprehensive balance and improvement in performance, including high carrier mobility, excellent optical transmittance, and low film stress, through a combination of stress buffering and crystallization control agents, along with liquid-phase assisted impregnation and low-temperature activation annealing. Example 1, as the optimal solution, exhibited excellent carrier mobility, visible light transmittance, and low compressive stress, indicating that its film possesses excellent electrical conductivity, optical quality, and a stable mechanical state. Comparative Example 1, due to the complete absence of stress buffering and crystallization control agents, showed a sharp decrease in carrier mobility, a significant increase in resistivity, extremely high film compressive stress, and the lowest transmittance. This demonstrates that the agents are the material basis for effective doping, controlling carrier concentration, and releasing internal stress in the film; their absence leads to deterioration of the film's electrical properties and a high-stress unstable state. Comparative Example 2, due to the absence of vinyltriethoxysilane in the agents, showed some improvement in film compressive stress compared to Comparative Example 1, but it was still much higher than that of Example 1, and the mobility decreased significantly. This indicates that the flexible Si-O-Si network formed by the hydrolysis and condensation of vinyltriethoxysilane is a key component for buffering and relaxing internal stress in the thin film. Its absence significantly reduces the stress buffering effect, and the higher defect state density further impairs carrier mobility. Comparative Examples 3 and 4, due to the absence of ammonium nitrate or urea in the additives, showed lower carrier concentrations and mobilities than Example 1. This demonstrates that the combination of ammonium nitrate and urea, as a synergistic nitrogen source with controlled release, is crucial for achieving uniform and effective nitrogen doping, thereby precisely controlling the type and concentration of carriers. The absence of either component leads to a decrease in doping efficiency and impaired electrical performance. Comparative Example 5, due to the absence of zinc oxide nanocrystals in the additives, experienced affected thin film grain growth, resulting in lower carrier mobility, increased resistivity, and higher film stress. This indicates that dispersed zinc oxide nanocrystals, as heterogeneous nucleation sites, play a key guiding role in promoting the uniform and ordered crystallization of the oxide semiconductor matrix at low temperatures. Their absence is detrimental to the formation of high-quality crystal structures, thus limiting the improvement of electrical performance and increasing structural stress. Comparative Example 6 employed a one-step process to add all additives. While its performance was superior to Comparative Examples 2-5, which lacked key components, it was inferior to Example 1, which used a two-step process. Specifically, it exhibited lower carrier mobility, higher film stress, and poor nitrogen doping uniformity as shown by XPS. This directly and powerfully demonstrates that introducing additives in two steps, especially by introducing the second part of the additives through liquid-phase assisted impregnation after pre-curing and supplemented by solvent vapor treatment, can achieve a more uniform spatial distribution of dopants, a more complete stress buffer network, and a more optimized crystallization process compared to simple one-time physical mixing.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A crystal implantation process for display thin films, characterized in that, The method includes the following steps: S1. Preparation of stress buffering and crystallization regulating agents; S2. Preparation of basic composite precursor solution A. The raw materials for preparing basic composite precursor solution A include, by weight, 10.5-14 parts indium nitrate pentahydrate, 3.7-4.5 parts gallium nitrate hexahydrate, 6.2-6.8 parts zinc acetate dihydrate, 64-70 parts propylene glycol methyl ether acetate, 2.0-2.5 parts acetylacetone, 15-20 parts stress buffer and crystallization regulating agent prepared in step S1, and 0.2-0.5 parts polyether modified polysiloxane surfactant. S3. Thin film deposition, gradient drying and pre-curing: The basic composite precursor solution A is spin-coated onto the substrate, and the wet film is gradient dried and pre-cured on a precision temperature-controlled hot plate to obtain a pre-cured thin film sample. S4, Liquid-phase assisted impregnation and low-temperature activation annealing: The stress buffer and crystallization regulator were diluted with propylene glycol methyl ether acetate to obtain impregnation solution B, which was coated on the surface of the thin film sample and treated. The first gradient annealing was carried out under a low oxygen atmosphere. S5. Crystallization and Stabilization Annealing: A second rapid thermal annealing is performed in an inert gas atmosphere to complete crystal implantation.

2. The method as described in claim 1, characterized in that, The raw materials for preparing the stress buffer and crystallization regulating agent, by weight, include: 8-12.5 parts vinyltriethoxysilane, 2.2-2.8 parts ammonium nitrate, 3.5-4.2 parts urea, 3.5-6 parts zinc oxide nanocrystals, 2.2-3 parts acetylacetone, 0.6-0.8 parts polyether-modified polysiloxane surfactant, and 70.7-80 parts propylene glycol methyl ether acetate.

3. The method as described in claim 1, characterized in that, Step S1 specifically includes: under nitrogen protection, adding 55.7-80 parts of propylene glycol methyl ether acetate, stirring at 400 rpm, adding vinyltriethoxysilane and acetylacetone; increasing the stirring speed to 600 rpm, raising the temperature to 45-50℃, and stirring for 80-90 minutes; dissolving ammonium nitrate and urea separately in deionized water, and then adding them dropwise with polyether-modified polysiloxane surfactant at a rate of 1 drop per second for 100-120 minutes; adding a zinc oxide nanocrystal dilution solution pre-dispersed with propylene glycol methyl ether acetate, increasing the stirring speed to 800 rpm, raising the temperature to 60-65℃, and stirring for 150-180 minutes; cooling the reaction solution to below 30℃, and filtering through a 0.1-micron filter cartridge to obtain a stress buffer and crystallization regulating agent.

4. The method as described in claim 1, characterized in that, Step S2 specifically includes: In a clean room with constant temperature and humidity of 23℃ and 35% relative humidity, propylene glycol methyl ether acetate solvent is added to a reaction flask and stirred at 300 rpm. Indium nitrate pentahydrate, gallium nitrate hexahydrate, and zinc acetate dihydrate are added. The stirring speed is increased to 500 rpm, the system temperature is maintained at 25℃, acetylacetone is added, and the mixture is stirred for 100-120 minutes to form a metal complex base solution. Stress buffer and crystallization regulator are added, the stirring speed is increased to 800 rpm, the temperature is raised to 38-40℃, and the mixture is stirred for 150-180 minutes. Polyether-modified polysiloxane surfactant is added, the stirring speed is adjusted to 400 rpm, and the mixture is aged at 38-40℃ for 40-60 minutes. The mixture is then filtered through a 0.2-micron filter membrane to obtain the basic composite precursor solution A.

5. The method as described in claim 1, characterized in that, In step S3, the spin coating parameters are: 100 revolutions per second. 2 The acceleration will increase the substrate rotation speed to 800 rpm and maintain it for 10 seconds, then at 500 rpm. 2 The acceleration reaches 3000 rpm and is maintained for 20-30 seconds; Gradient drying and pre-curing consists of three stages: the first stage is to stand at 80-90℃ for 60-90 seconds; the second stage is to heat up to 120-130℃ and hold for 120-180 seconds; the third stage is to heat up to 210-220℃ and hold for 250-300 seconds.

6. The method as described in claim 1, characterized in that, In step S4, the impregnation solution B is obtained by diluting the stress buffer and crystallization regulating agent prepared in step S1 with propylene glycol methyl ether acetate to 50%-60% of its original viscosity; the coating method is spraying, and the coating amount is 2.5-3.0 μL per square centimeter of film surface; after coating, the sample is placed in a sealed chamber filled with saturated propylene glycol methyl ether acetate vapor at 25°C and left to stand for 80-120 seconds.

7. The method as described in claim 1, characterized in that, In step S4, the first gradient annealing is carried out in a tubular annealing furnace, specifically including: purging with high-purity nitrogen for 5-10 minutes, then switching the atmosphere to a nitrogen-oxygen mixture with an oxygen volume fraction of 1%-2%; raising the temperature from room temperature to 265-280℃ at a rate of 2-3℃ / min, and holding at 265-280℃ for 20-40 minutes; and cooling down to below 150℃ at a rate of 2-3℃ / min.

8. The method as described in claim 1, characterized in that, In step S5, the second rapid thermal annealing is carried out in a rapid thermal annealing equipment. The specific conditions are as follows: under a pure nitrogen atmosphere, the sample surface temperature is raised to 365-380℃ at a heating rate of 20-30℃ / second, and held at 365-380℃ for 3-8 minutes, and then naturally cooled to room temperature.

9. The method as described in claim 1, characterized in that, Before adding the zinc oxide nanocrystal diluent in step S1, the zinc oxide nanocrystals are pretreated by mixing and dispersing them with propylene glycol methyl ether acetate to obtain the zinc oxide nanocrystal diluent.

10. The method as described in claim 9, characterized in that, Zinc oxide nanocrystals were mixed with propylene glycol methyl ether acetate and dispersed by high-speed shearing at 3000 rpm for 10-15 minutes to obtain a diluted zinc oxide nanocrystal solution.

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