MOS (Metal Oxide Semiconductor) target material, preparation method thereof and thin film transistor

Abstract

The invention relates to the technical field of target material preparation, and provides an MOS target material, a preparation method thereof and a thin film transistor, and the preparation method comprises the steps: carrying out a co-precipitation reaction on a mixed salt solution of In, Ga and Sn ions, a precipitator and a complexing agent, and carrying out cleaning and concentration to obtain a high-purity indium gallium tin hydroxide colloid; carrying out hydrothermal reaction on the indium gallium tin hydroxide colloid and an auxiliary agent, and cleaning and drying to obtain first indium gallium tin oxide powder; calcining the first indium gallium tin oxide powder to obtain second indium gallium tin oxide powder; ball-milling and mixing second indium gallium tin oxide powder, a dispersing agent, a defoaming agent and pure water to obtain slurry; performing slip casting on the slurry to obtain a biscuit; and sintering the biscuit under a high-oxygen condition to obtain the MOS target material. The co-precipitation reaction, the hydrothermal reaction and the calcination are combined, the oxygen content of the powder is accurately controlled, the powder is slightly deoxygenated, and the situation that in the biscuit sintering process, In2O3 deoxygenates to generate In2O or InO, and consequently the conductivity of the target material is affected is prevented.

Description

Technical Field

[0001] The present application belongs to the technical field of target material preparation, and in particular, relates to a MOS target material, a preparation method thereof, and a thin film transistor. Background Art

[0002] MOS (Metal-Oxide-Semiconductor) thin film has the advantages of high mobility, low preparation temperature, transparency in the visible light band and good electrical stability. It is an ideal material for the active layer of oxide thin film transistors (TFTs). With the rapid development of display technology towards large size, ultra-high definition, ultra-high refresh rate, and low power consumption, higher requirements are placed on the mobility of TFTs. At present, the mobility of commonly used IGZO (In-Ga-Zn oxide) TFTs is about 20cm 2 ·V -1 ·s -1 , but it is still far below the application standard of the next generation display technology. In addition, since the IGZO film contains Zn elements, it is easily etched during wet etching of the source and drain electrodes, and the ZnO in the IGZO film is sensitive to temperature, water vapor, etc., which can easily lead to unstable electrical performance of the IGZO TFT during continuous operation. Therefore, it is necessary to develop a MOS target material that does not contain ZnO to overcome the problem of poor stability of IGZO.

[0003] In addition, the current preparation method of IGZO target materials usually adopts air normal pressure sintering. However, the In2O3 in the green body is easily deoxygenated to form In2O or InO during high temperature sintering under normal pressure air conditions, which affects the conductivity, composition and organizational uniformity and density of the IGZO target material, and further affects the film quality of the target material. Summary of the invention

[0004] The purpose of this application is to provide a MOS target material, a preparation method thereof and a thin film transistor, aiming to solve the problems of poor electrical performance stability of the existing IGZO target material and easy oxygen loss during the sintering process, which affects the conductivity, composition and organizational uniformity and density of the target material.

[0005] In order to achieve the above application purpose, the technical solution adopted in this application is as follows: In a first aspect, the present application provides a method for preparing a MOS target, comprising the following steps: A mixed salt solution of In, Ga and Sn ions, a precipitant and a complexing agent are subjected to a coprecipitation reaction, and a high-purity indium gallium tin hydroxide colloid is obtained after washing and concentration; After the high-purity indium gallium tin hydroxide colloid and the auxiliary agent are subjected to a hydrothermal reaction, the first indium gallium tin oxide powder is obtained by washing and drying; calcining the first indium gallium tin oxide powder to obtain a second indium gallium tin oxide powder; The second indium gallium tin oxide powder, a dispersant, a defoamer and pure water are ball-milled to obtain a slurry; Slip-casting the slurry to obtain a green blank; The green blank is sintered under high oxygen conditions to obtain a MOS target.

[0006] In a second aspect, the present application provides a MOS target material, including a MOS target material prepared by the MOS target material preparation method provided in the present application.

[0007] In a third aspect, the present application provides a thin film transistor, including an active layer thin film, wherein the active layer thin film is obtained by sputtering and coating the MOS target material provided by the present application.

[0008] Compared with the prior art, this application has the following beneficial effects: (1) After a mixed salt solution of In, Ga and Sn ions is subjected to a coprecipitation reaction to obtain a high-purity indium gallium tin hydroxide colloid, an auxiliary agent is added for a hydrothermal reaction to obtain a first indium gallium tin oxide powder in which each component is evenly distributed, and the powder is slightly deoxygenated. The powder particle size is then increased by calcination to facilitate molding, thereby improving the density and strength of the blank, thereby helping to provide the target material density. At the same time, by controlling the calcination conditions, the oxygen content of the generated second indium gallium tin oxide powder can be more accurately controlled and slightly deoxygenated, thereby preventing In2O3 from losing oxygen during the sintering process of the blank to generate low-valent indium oxide (such as In2O or InO) and affecting the conductivity and oxygen content of the target material. Therefore, compared with the conventional method of sintering a mixed powder of indium oxide, gallium oxide and tin oxide using air at normal pressure, the sintering process of the present application is simple, the target material composition and structure are uniform, there is no segregation, the density is high and the conductivity is good.

[0009] (2) Compared with IGZO target, the MOS target of the present application does not contain ZnO. On the one hand, it avoids the problem that ZnO is sensitive to temperature, water vapor, etc. and easily affects the electrical stability of TFT continuous operation. On the other hand, Sn can increase the carrier concentration and improve the conductivity of the target. 4+ The ionic radius of In 3+ The closer they are, the easier it is to form a high-mobility channel, which helps to improve the mobility of the TFT. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 is a process flow chart of a method for preparing a MOS target material provided in an embodiment of the present application; Figure 2 This is a SEM image of the MOS target material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0012] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0013] In the embodiment of the present application, the MOS target refers to a metal oxide semiconductor target, specifically an IGTO target.

[0014] In a first aspect, an embodiment of the present application provides a method for preparing a MOS target material, such as Figure 1 As shown, the following steps are included: S01: a mixed salt solution of In, Ga and Sn ions, a precipitant and a complexing agent are subjected to a co-precipitation reaction, and a high-purity indium gallium tin hydroxide colloid is obtained after washing and concentration; S02: subjecting a high-purity indium gallium tin hydroxide colloid and an additive to a hydrothermal reaction, and then washing and drying to obtain a first indium gallium tin oxide powder; S03: calcining the first indium gallium tin oxide powder to obtain a second indium gallium tin oxide powder; S04: ball-milling the second indium gallium tin oxide powder, the dispersant, the defoaming agent and pure water to obtain a slurry; S05: Slurry is cast into shape to obtain a green blank; S06: Sintering the green blank under high oxygen conditions to obtain a MOS target.

[0015] The preparation method of the MOS target provided in the embodiment of the present application is to subject a mixed salt solution of three ions of In, Ga and Sn to a coprecipitation reaction to obtain a high-purity indium gallium tin hydroxide colloid, and then add an auxiliary agent to carry out a hydrothermal reaction, so as to obtain a first indium gallium tin oxide powder with uniform distribution of each component, and slightly deoxygenate it, and then increase the particle size of the powder by calcination to facilitate molding, improve the density and strength of the blank, thereby helping to provide the density of the target material, and at the same time, by controlling the calcination conditions, the oxygen content of the generated second indium gallium tin oxide powder can be more accurately controlled and slightly deoxygenated, so as to prevent In2O3 from losing oxygen to generate low-valent indium oxide (such as In2O or InO) during the sintering of the blank, thereby affecting the conductivity and oxygen content of the target material; therefore, compared with the conventional mixed powder of indium oxide, gallium oxide and tin oxide sintering method using air at normal pressure, the sintering process of the present application is simple in reaction, the target material composition and organization are uniform, there is no segregation, the density is high and the conductivity is good. Compared with IGZO target, the MOS target of the present application does not contain ZnO. On the one hand, it avoids the problem that ZnO is sensitive to temperature, water vapor, etc. and easily affects the electrical stability of TFT continuous operation. On the other hand, Sn can increase the carrier concentration and improve the conductivity of the target. 4+ The ionic radius of In 3+ The closer they are, the easier it is to form a high-mobility channel, which helps to improve the mobility of the TFT.

[0016] In the above step S01, in the embodiment, the step of preparing a mixed salt solution of three ions of In, Ga and Sn includes: adding indium salt, gallium salt and tin salt to pure water and stirring evenly to obtain a mixed salt solution of three ions of In, Ga and Sn. Wherein, the mass ratio of In, Ga and Sn in the mixed salt solution is (34.7~67.4): (1.5~27.5): (13.0~16.5); the indium salt is selected from InCl3 powder, the gallium salt is selected from GaCl3 powder, and the tin salt is selected from SnCl4·5H2O.

[0017] In the embodiment, the coprecipitation reaction temperature is 50-65° C., the time is 6-8 hours, and the pH value is 8.5-9.5.

[0018] In an embodiment, the precipitating agent is selected from ammonia water or sodium hydroxide; and the complexing agent is selected from ammonium nitrate or ammonium chloride.

[0019] In the above step S02, in the embodiment, the temperature of the hydrothermal reaction is 150-250°C and the time is 12-24h. Under the hydrothermal conditions, the additive has a reducing effect, so that the generated first indium gallium tin oxide powder is slightly deoxygenated, which is beneficial to prevent In2O3 from losing oxygen to generate In2O or InO during the subsequent sintering process and affecting the conductivity of the target material, and the phase change is simple, which is beneficial to improve the uniformity of the target material structure. In addition, through the hydrothermal reaction, the hard agglomeration of the powder caused by the traditional mechanical ball milling can be avoided, the uniformity and dispersibility of the powder are improved, and the powder sintering activity is higher, which helps to improve the purity, uniformity and density of the MOS target material.

[0020] In the embodiment, the mass ratio of high-purity indium gallium tin hydroxide colloid to the auxiliary agent is (1-2): (0.01-0.05). The auxiliary agent is selected from sucrose, glucose, fructose and the like.

[0021] In an embodiment, the primary particle size of the first indium gallium tin oxide powder is 0.05-0.1 μm.

[0022] In the above step S03, in the embodiment, the calcination treatment atmosphere is an argon-hydrogen mixed gas with a volume ratio of argon to hydrogen of (95-99): (1-5), the temperature is 600-800°C, and the time is 4-10 hours. The calcination conditions are conducive to the growth of the first indium gallium tin oxide powder to increase the particle size for subsequent molding, and can more accurately control the oxygen content of the generated second indium gallium tin oxide powder and maintain slight oxygen loss.

[0023] In the embodiment, in the second indium gallium tin oxide powder, the mass ratio of In, Ga and Sn is (34.7-67.4): (1.5-27.5): (13.0-16.5).

[0024] In an embodiment, the oxygen content of the second InGaTnO powder is less than that of the MOS target, which helps prevent the second InGaTnO powder from losing oxygen to generate In2O or InO during the subsequent sintering process, thereby affecting the conductivity and density of the target.

[0025] In an embodiment, the particle size of the second indium gallium tin oxide powder is 0.2-0.5 μm, and this particle size range is conducive to powder slip casting and improves the density and strength of the green billet.

[0026] In the above step S04, in an embodiment, the step of mixing the second indium gallium tin oxide powder, dispersant, defoamer and pure water by ball milling includes: adding the second indium gallium tin oxide powder, dispersant, defoamer and pure water into a ball milling jar, and ball milling at a speed of 200-1000 rpm for 6-18 hours to obtain a slurry.

[0027] In the embodiment, the solid content of the slurry is 60-70%.

[0028] In an embodiment, the amount of the dispersant added is 0.1-1% of the mass of the second indium gallium tin oxide powder. Specifically, the dispersant can be selected from one or more of polyethylene glycol, hexadecyl sulfonate, polycarboxylate, polyacrylate or triethanolamine.

[0029] In an embodiment, the amount of the defoamer added is 0.1-0.5% of the mass of the second indium gallium tin oxide powder. Specifically, the defoamer can be selected from polyether defoamers and / or higher alcohols.

[0030] In the above step S05, in the embodiment, the step of slip injection molding the slurry includes: loading the slurry into a vacuum tank, and after vacuum degassing, injecting the slurry into a sealed resin or graphite mold cavity at a pressure of 0.2~1.5MPa until no water drips out of the mold, opening the mold, taking out the solidified blank, and standing it at room temperature for 24h to obtain a blank.

[0031] In the above step S06, in the embodiment, the step of sintering the green blank under high oxygen conditions includes: placing the green blank into an alumina sleeve and placing it in a sintering furnace, and then evacuating the alumina sleeve to a vacuum degree of 10 -2 ~10 - 3 Pa, oxygen is introduced and the oxygen pressure of the alumina sleeve is set to 0.05-0.1 MPa, and then the temperature is raised to 1400-1600°C for heat preservation sintering for 12-48 hours. In this embodiment, the blank is placed in the alumina sleeve and then placed in the sintering furnace, so that the blank is sintered in a narrow space, which is conducive to the precise control of the uniformity of airflow and temperature. It can not only slow down the heat exchange between the blank and the furnace, reduce temperature fluctuations, make the blank heated more evenly, reduce deformation or cracking caused by thermal stress, and improve the uniformity of the target material structure, but also ensure that the sintering airflow field and temperature field of different production batches are the same, so that the target material produced has stable performance and good repeatability. In addition, by controlling the oxygen pressure of the alumina sleeve, the blank is sintered under high oxygen conditions, which helps the slightly deoxygenated second indium gallium tin oxide powder to fully oxidize to form a target material with uniform composition and good conductivity, and prevent In2O3 in the powder from losing oxygen to generate In2O or InO, which affects the conductivity and density of the target material. In addition, the use of alumina sleeves can also reduce oxygen consumption and reduce costs.

[0032] In an embodiment, the relative density of the MOS target material is ≥98.5%, and the resistivity is ≤10 mΩ·cm.

[0033] A second aspect of an embodiment of the present application provides a MOS target material, including a MOS target material prepared by the MOS target material preparation method provided in the present application.

[0034] The MOS target material provided in the embodiment of the present application is prepared by the preparation method of the MOS target material provided in the embodiment of the present application, so the target material has the advantages of high density, good uniformity of composition and organization, low resistivity and good stability.

[0035] A third aspect of an embodiment of the present application provides a thin film transistor, comprising an active layer thin film, wherein the active layer thin film is obtained by sputtering and coating the MOS target material provided by the present application.

[0036] The thin film transistor provided in the embodiment of the present application has the advantages of low resistivity, high carrier concentration and high mobility, as well as good stability to water, oxygen, light and heat, because its active layer thin film is obtained by sputtering and coating the metal oxide semiconductor target material provided in the embodiment of the present application. Therefore, it can improve the performance indicators such as the mobility, threshold voltage and current switching ratio of the TFT, improve the reliability problems that are prone to occur when the TFT works for a long time, and increase the life of the TFT, thereby helping to achieve high resolution, high refresh rate, low power consumption and high definition of the display screen, and improve the stability of the display screen.

[0037] The following describes the invention in conjunction with specific embodiments.

[0038] Example 1 This embodiment provides a method for preparing a MOS target material, comprising the following steps: S11: according to the mass ratio of In, Ga, Sn being 37.6:27.5:14.3, appropriate amounts of InCl3 powder, GaCl3 powder and SnCl4·5H2O are weighed and added into pure water and stirred evenly to obtain a mixed salt solution of In, Ga and Sn ions; the mixed salt solution of In, Ga and Sn ions, sodium hydroxide solution and ammonia solution are added into a reactor and mixed, the temperature of the reactor is controlled at 60°C, the pH value of the reaction system is 9, a coprecipitation reaction is carried out for 7 hours, and a high-purity indium gallium tin hydroxide colloid is obtained after washing and concentration; S12: according to the mass ratio of 1.5:0.03, weigh appropriate amounts of high-purity indium gallium tin hydroxide colloid and glucose, add them into pure water and stir evenly to obtain a suspension (concentration of 0.5 mol / L); The suspension was transferred to the inner tank of the reactor, and an appropriate amount of pure water was added so that the final volume of the suspension was 70% of the volume of the inner tank of the reactor. The reactor was placed in a drying oven at 200°C for hydrothermal reaction for 18 hours. The precipitate obtained by centrifugal separation was then repeatedly washed with pure water and anhydrous ethanol, and the first indium gallium tin oxide powder (D50 = 0.08 μm after detection) was obtained after drying. S13: placing the first indium gallium tin oxide powder in an atmosphere sintering furnace and evacuating the furnace to 10 -2After the temperature reaches 0.500 Pa, a mixed gas of argon and hydrogen (the volume ratio of argon to hydrogen is 98:2) is introduced, and the temperature is raised to 750°C. The mixture is kept at this temperature for 6 hours to obtain a second indium gallium tin oxide powder (D50=0.35μm after detection). S14: adding the second indium gallium tin oxide powder, polyethylene glycol, polyoxypropylene glycerol ether and pure water into a ball mill, and ball milling at a speed of 500 rpm for 12 hours to obtain a slurry (solid content of 65%); the amount of polyethylene glycol added is 0.5% of the mass of the second indium gallium tin oxide powder, and the amount of polyoxypropylene glycerol ether added is 0.3% of the mass of the second indium gallium tin oxide powder; S15: The slurry is placed in a vacuum tank, and after vacuum degassing, the slurry is injected into the sealed graphite mold cavity at a pressure of 1 MPa until no water drips out of the mold. The mold is opened, the solidified green body is taken out, and it is allowed to stand at room temperature for 24 hours to obtain a green body.

[0039] S16: The green blank is placed in an alumina sleeve and placed in a sintering furnace. The alumina sleeve is then evacuated to a vacuum degree of 5×10 -2 Pa, oxygen was introduced and the oxygen pressure of the alumina sleeve was set to 0.08 MPa. The temperature was then raised to 1500°C and sintered for 36 hours to obtain a MOS target.

[0040] Comparative Example 1 This comparative example provides a method for preparing a MOS target material, which is different from Example 1 in that: Step S12 is not performed; In step S13, the high-purity indium gallium tin hydroxide colloid is placed in a sintering furnace, heated to 750° C. in an air atmosphere, and calcined for 6 hours to obtain a second indium gallium tin oxide powder (D50=0.41 μm after detection).

[0041] Comparative Example 2 This comparative example provides a method for preparing a MOS target material, which is different from Example 1 in that: Step S13 is not performed; Step S14 is to add the first indium gallium tin oxide powder, polyethylene glycol, polyoxypropylene glycerol ether and pure water into a ball mill.

[0042] Comparative Example 3 This embodiment provides a method for preparing a MOS target material, which is different from Embodiment 1 in that: In step S15, the green blank is placed in a sintering furnace, and then the sintering furnace is evacuated to a vacuum degree of 5×10 - Oxygen was introduced at 400 ℃ and then the temperature was raised to 1500℃ for sintering for 36 hours to obtain a MOS target.

[0043] Comparative Example 4 This comparative example provides a method for preparing a MOS target material, comprising the following steps: S1: according to the mass ratio of indium, gallium and tin of 37.6:27.5:14.3, weigh appropriate amounts of indium oxide powder, gallium oxide powder and tin oxide powder; S2: Add indium oxide powder, gallium oxide powder, tin oxide powder, polyethylene glycol, polyoxypropylene glycerol ether and pure water into a ball mill, and ball mill at a speed of 500 rpm for 12 h to obtain a slurry; S3: The slurry is placed in a vacuum tank, and after vacuum degassing, the slurry is injected into the sealed graphite mold cavity at a pressure of 1 MPa until no water drips out of the mold, the mold is opened, the solidified green body is taken out, and it is left to stand at room temperature for 24 hours to obtain a green body; S4: Place the green blank in a sintering furnace, and then evacuate the sintering furnace to a vacuum degree of 5×10 - Oxygen was introduced at 400 ℃ and then the temperature was raised to 1500℃ for sintering for 36 hours to obtain a MOS target.

[0044] Related performance test analysis: 1. After the MOS target material is plastic-sealed, the density of the MOS target materials prepared in Example 1 and Comparative Examples 1 to 4 is tested respectively by using the Archimedes density test method; specifically, the MOS target material is cut into 5 sections along the cross section, and then the actual density of each section is tested respectively, and the relative density = actual density / theoretical density × 100% based on the theoretical density; the test results are shown in Table 1 below; 2. The resistivity of the MOS target materials prepared in Example 1 and Comparative Examples 1 to 4 was tested respectively using a four-probe tester; specifically, the resistivity of 5 different regions of the MOS target materials was tested respectively; the test results are shown in Table 2 below; 3. The O content of the MOS targets prepared in Example 1 and Comparative Examples 1 to 4 was tested using an oxygen and nitrogen analyzer; specifically, 5 samples were taken from different regions of the MOS target, and then the O content of each sample was tested; the test results are shown in Table 3 below; Among them, median uniformity = [(max-min) ÷ (max+min)] × 100%.

[0045] Table 1 Table 2 Table 3 It can be seen from Tables 1-2 that the relative density of the target material prepared in Example 1 is greater than 99.0% and the resistivity is less than 3 mΩ·cm, indicating that the preparation method of the embodiment of the present application can prepare a MOS target material with high density and low resistance.

[0046] The relative density of the target material prepared in Example 1 is significantly higher than that of Comparative Examples 3 and 4, and the median uniformity of the relative density of the target material prepared in Example 1 is significantly lower than that of Comparative Examples 3 and 4. This is mainly due to the fact that in the embodiment of the present application, the green blank is placed in an alumina sleeve for high-oxygen sintering, which can accurately control the uniformity of airflow and temperature, so that the green blank is heated evenly, thereby helping to improve the density and organizational uniformity of the target material and make its density distribution more uniform.

[0047] The relative density of Comparative Example 1 is lower than that of Example 1. The main reason may be that Comparative Example 1 directly calcined the high-purity InGaSn hydroxide colloid generated by the coprecipitation reaction in air, and failed to control the oxygen content of the InGaSn oxide powder, resulting in the loss of oxygen in In2O3 during subsequent sintering, leaving gaps, which is not conducive to the formation of a high-density target. The relative density of Comparative Example 2 is lower than that of Example 1. The main reason may be that the particle size of the powder obtained by the hydrothermal reaction in Comparative Example 2 is too fine, which is not conducive to slip casting, and thus is not conducive to the formation of a high-density target.

[0048] The resistivity and median resistivity uniformity of the target material prepared in Example 1 are significantly lower than those of Comparative Examples 1-2 and Comparative Example 4. This is mainly due to the combination of coprecipitation reaction, hydrothermal reaction and calcination in the embodiment of the present application. By adding glucose and high-purity indium gallium tin hydroxide colloid for hydrothermal reaction, the generated first indium gallium tin oxide powder is slightly deoxygenated, and the first indium gallium tin oxide powder is further calcined in an argon-hydrogen mixed atmosphere, which can more accurately control the oxygen content of the powder and maintain slight deoxygenation, so that it can be fully oxidized into stable In2O3 during subsequent high-oxygen sintering, avoiding the doping of low-valent indium oxides (such as InO or In2O) to affect the conductive properties, so the target material has a lower resistivity.

[0049] The resistivity and median resistivity uniformity of the target material prepared in Example 1 are lower than those in Comparative Example 3. The main reason may be that in the embodiment of the present application, the green blank is loaded into an alumina sleeve and then placed in a sintering furnace for sintering, which can accurately control the temperature and airflow, so that the green blank is heated more evenly, thereby the target material has good composition and organizational uniformity and low resistivity.

[0050] It can be seen from Table 3 that the oxygen content of each region of the target material prepared in Example 1 is 20.3-20.6, which is close to the theoretical value (20.6), and the median uniformity of the oxygen content is relatively small, while the oxygen content of each region of the target material prepared in Comparative Examples 1-2 is significantly lower than the theoretical value, and the median uniformity of the oxygen content is relatively large. This is mainly due to the combination of coprecipitation reaction, hydrothermal reaction and calcination in the embodiments of the present application to accurately control the oxygen content of the second indium gallium tin oxide powder and cause it to lose oxygen slightly, which can reduce the oxygen loss of In2O3 during the high-oxygen sintering process of the green billet and affect the oxygen content of the target material.

[0051] from Figure 2It can be seen from the SEM that the MOS target material prepared in Example 1 has uniform grains, close bonding between grains, and no obvious grain boundaries and pores.

[0052] It can be seen that the preparation method of the MOS target material provided in the embodiment of the present application can successfully prepare a MOS target material with good composition and organizational uniformity, high density, good conductivity and stable electrical properties. Therefore, the MOS film prepared by sputtering the MOS target material of the present application has the advantages of good uniformity, high carrier concentration and high mobility, and does not contain ZnO and has good stability to water, oxygen, light and heat.

[0053] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a MOS target, characterized in that: The following steps are involved: A mixed salt solution of In, Ga and Sn ions, a precipitant and a complexing agent are subjected to a coprecipitation reaction, and a high-purity indium gallium tin hydroxide colloid is obtained after washing and concentration; After the high-purity indium gallium tin hydroxide colloid and the auxiliary agent are subjected to a hydrothermal reaction, the first indium gallium tin oxide powder is obtained by washing and drying; calcining the first indium gallium tin oxide powder to obtain a second indium gallium tin oxide powder; The second indium gallium tin oxide powder, a dispersant, a defoamer and pure water are ball-milled to obtain a slurry; Slip-casting the slurry to obtain a green blank; The green blank is sintered under high oxygen conditions to obtain a MOS target.

2. The preparation method according to claim 1, characterized in that At least one of the following conditions is met: The oxygen content of the second indium gallium tin oxide powder is less than the oxygen content of the MOS target; The primary particle size of the first indium gallium tin oxide powder is 0.05-0.1 μm; The particle size of the second indium gallium tin oxide powder is 0.2-0.5 μm.

3. The preparation method according to claim 1, characterized in that: At least one of the following conditions is met: The steps of preparing a mixed salt solution of three ions of In, Ga and Sn include: adding indium salt, gallium salt and tin salt into pure water and stirring evenly to obtain a mixed salt solution of three ions of In, Ga and Sn; The coprecipitation reaction temperature is 50-65°C, the reaction time is 6-8h, and the pH value is 8.5-9.5; The precipitant is selected from ammonia water or sodium hydroxide; The complexing agent is selected from ammonium nitrate or ammonium chloride.

4. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 150-250°C and the time is 12-24h; And / or, the mass ratio of the high-purity indium gallium tin hydroxide colloid to the auxiliary agent is (1-2): (0.01-0.05); And / or, the auxiliary agent is selected from any one of sucrose, glucose or fructose.

5. The preparation method according to claim 1, characterized in that: The calcination treatment atmosphere is an argon-hydrogen mixed gas with a volume ratio of argon to hydrogen of (95-99): (1-5), the temperature is 600-800° C., and the time is 4-10 hours.

6. The preparation method according to claim 1, characterized in that: In the second indium gallium tin oxide powder, the mass ratio of In, Ga and Sn is (34.7-67.4): (1.5-27.5): (13.0-16.5); And / or, the solid content of the slurry is 60-70%.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The step of sintering the green blank under high oxygen conditions comprises: The green blank is placed in an alumina sleeve and placed in a sintering furnace, and then the alumina sleeve is evacuated to a vacuum degree of 10 -2 ~10 -3 Pa, oxygen is introduced to make the oxygen pressure of the alumina sleeve 0.05-0.1 MPa, and then the temperature is raised to 1400-1600° C. for heat preservation and sintering for 12-48 hours.

8. The preparation method according to claim 7, characterized in that: The relative density of the MOS target material is ≥98.5%, and the resistivity is ≤10 mΩ·cm.

9. A MOS target material, characterized in that: A MOS target material prepared by the method for preparing a MOS target material according to any one of claims 1 to 8.

10. A thin film transistor, comprising an active layer thin film, characterized in that: The active layer thin film is obtained by sputtering and coating the MOS target material according to claim 9.

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