MOS target material, preparation method therefor, and thin-film transistor

Abstract

The present application relates to the technical field of target material preparation. Provided are a MOS target material, a preparation method therefor, and a thin-film transistor. The preparation method comprises: subjecting a mixed salt solution of In, Ga, and Sn ions, a precipitant, and a complexing agent to a coprecipitation reaction, then performing cleaning and concentration to obtain a high-purity indium gallium tin hydroxide colloid; subjecting the high-purity indium gallium tin hydroxide colloid and an auxiliary agent to a hydrothermal reaction, then performing cleaning and drying to obtain a first indium gallium tin oxide powder; calcining the first indium gallium tin oxide powder to obtain a second indium gallium tin oxide powder; subjecting the second indium gallium tin oxide powder, a dispersant, a defoaming agent, and pure water to ball milling and mixing so as to obtain a slurry; performing slip casting using the slurry to obtain a green body; and sintering the green body under high-oxygen conditions to obtain a MOS target material. The present application combines a coprecipitation reaction, a hydrothermal reaction, and calcination, precisely controlling the oxygen content of the powder and making the powder slightly oxygen deficient, and preventing In2O3 from losing oxygen and generating In2O or InO during sintering of the green body and affecting the conductivity of the target material.

Description

MOS target material, preparation method thereof and thin film transistor

[0001] The present application claims priority to the Chinese patent application No. 202510194523.2, filed on February 21, 2025, and entitled "MOS target material, preparation method thereof and thin film transistor", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the technical field of target material preparation, and particularly relates to a MOS target material, a preparation method thereof and a thin film transistor. BACKGROUND

[0003] 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, and is an ideal material for the active layer of oxide thin film transistor (TFT). With the rapid development of display technology towards large size, ultra-high definition, ultra-high refresh rate, low power consumption and other directions, higher requirements are put forward for the mobility of TFT. At present, the mobility of commonly used IGZO (In-Ga-Zn oxide) TFT is about 20 cm 2 ·V -1 ·s -1 However, it is still far below the application standard of the next generation of display technology. Moreover, the IGZO film is susceptible to etching in the source and drain wet etching due to the presence of Zn element, and the ZnO in the IGZO film is sensitive to temperature and water vapor, 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 without ZnO to overcome the problem of poor stability of IGZO.

[0004] In addition, the current preparation method of IGZO target material usually adopts air pressure sintering. However, In2O3 in the compact body is easy to lose oxygen and generate In2O or InO under high-temperature sintering in air at normal pressure, thereby affecting the electrical conductivity, composition and uniformity of the organization, and the density of the IGZO target material, which can further affect the film forming quality of the target material. SUMMARY

[0005] The present application aims to provide a MOS target material, a preparation method thereof and a thin film transistor, and aims to solve the problems of poor electrical performance stability and easy oxygen loss during sintering process, which affects the electrical conductivity, composition and uniformity of the organization, and the density of the target material.

[0006] To achieve the above application purpose, the technical solution adopted by the present application is as follows:

[0007] In a first aspect, the application provides a preparation method of a MOS target material, comprising the following steps:

[0008] a mixed salt solution of In, Ga and Sn ions, a precipitant and a complexing agent are subjected to a co-precipitation reaction, and after washing and concentration, high-purity indium gallium tin hydroxide colloid is obtained;

[0009] the high-purity indium gallium tin hydroxide colloid and an auxiliary agent are subjected to a hydrothermal reaction, and after washing and drying, a first indium gallium tin oxide powder is obtained;

[0010] the first indium gallium tin oxide powder is subjected to calcination treatment, and a second indium gallium tin oxide powder is obtained;

[0011] the second indium gallium tin oxide powder, a dispersing agent, an antifoaming agent and pure water are ball-mixed to obtain a slurry;

[0012] the slurry is formed by injection molding to obtain a green body;

[0013] the green body is subjected to sintering treatment under a high-oxygen condition to obtain a MOS target material.

[0014] Optionally, the preparation method satisfies at least one of the following conditions:

[0015] the oxygen content of the second indium gallium tin oxide powder is less than that of the MOS target material;

[0016] the primary particle size of the first indium gallium tin oxide powder is 0.05-0.1 μm;

[0017] the particle size of the second indium gallium tin oxide powder is 0.2-0.5 μm.

[0018] Optionally, the preparation method satisfies at least one of the following conditions:

[0019] the step of preparing the mixed salt solution of In, Ga and Sn ions comprises: adding indium salt, gallium salt and tin salt into pure water and stirring uniformly to obtain the mixed salt solution of In, Ga and Sn ions;

[0020] the temperature of the co-precipitation reaction is 50-65℃, the time is 6-8 h, and the pH value is 8.5-9.5;

[0021] the precipitant is selected from ammonia water or sodium hydroxide;

[0022] the complexing agent is selected from ammonium nitrate or ammonium chloride.

[0023] Optionally, the temperature of the hydrothermal reaction is 150-250℃, and the time is 12-24 h.

[0024] Optionally, the mass ratio of the high-purity indium-gallium-tin hydroxide colloid and the auxiliary agent is (1-2):(0.01-0.05).

[0025] Optionally, the auxiliary agent is any one of sucrose, glucose or fructose.

[0026] Optionally, the atmosphere of the calcination treatment is argon-hydrogen mixed gas with a volume ratio of argon to hydrogen being (95-99):(1-5), a temperature being 600-800℃, and a time being 4-10h.

[0027] Optionally, 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).

[0028] Optionally, the solid content of the slurry is 60-70%.

[0029] Optionally, the addition amount of the dispersant is 0.1-1% of the mass of the second indium-gallium-tin oxide powder.

[0030] Optionally, the addition amount of the defoaming agent is 0.1-0.5% of the mass of the second indium-gallium-tin oxide powder.

[0031] Optionally, the dispersant is at least one of polyethylene glycol, cetyl sulfonate, polycarboxylate, polyacrylate or triethanolamine.

[0032] Optionally, the defoaming agent is selected from polyether defoaming agents and / or high-carbon alcohol.

[0033] Optionally, the step of sintering the green body under high-oxygen conditions comprises:

[0034] After the green body is loaded into an alumina sleeve, the alumina sleeve is placed in a sintering furnace, and then the alumina sleeve is vacuumized, and when the vacuum degree is 10 -2 ~10 -3 Pa, oxygen is introduced, and the oxygen pressure of the alumina sleeve is 0.05-0.1MPa, and then the temperature is raised to 1400-1600℃ for heat preservation sintering for 12-48h.

[0035] Optionally, the relative density of the MOS target material is ≥98.5%, and the resistivity is ≤10mΩ·cm.

[0036] In a second aspect, the application provides a MOS target material, which is prepared by the preparation method of the MOS target material provided by the application.

[0037] In a third aspect, the application provides a thin film transistor, which comprises an active layer film, and the active layer film is obtained by sputtering the MOS target material provided by the application.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] (1) After the mixed salt solution of In, Ga and Sn ions is subjected to co-precipitation reaction to obtain high-purity indium gallium tin hydroxide colloid, an additive is added to perform hydrothermal reaction, the first indium gallium tin oxide powder with uniform distribution of each component can be obtained, and the first indium gallium tin oxide powder is slightly deoxidized, and then the powder particle size is increased by calcination, so as to facilitate molding, improve the density and strength of the green body, thereby helping to provide the target density, and by controlling the calcination conditions, the oxygen content of the second indium gallium tin oxide powder generated can be more accurately controlled and slightly deoxidized, and the deoxidation of In2O3 to generate low-valence indium oxide (such as In2O or InO) during the sintering process of the green body is prevented, thereby affecting the conductivity and oxygen content of the target. Therefore, compared with the conventional mixed powder of indium oxide, gallium oxide and tin oxide using the air normal pressure sintering method, the sintering process of the present application is simple, the target composition and uniformity are good, there is no segregation, the density is high, and the conductivity is good.

[0040] (2) Compared with the IGZO target, the MOS target of the present application does not contain ZnO, which can avoid the problem that ZnO is sensitive to temperature and water vapor and easily affects the electrical stability of the continuous work of the TFT, and on the other hand, Sn can increase the carrier concentration and improve the conductivity of the target, and the ionic radius of Sn 4+ is closer to that of In 3+ , and it is easier to form a high-mobility channel, thereby helping to improve the mobility of the TFT. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any creative labor.

[0042] FIG. 1 is a process flow diagram of the preparation method of the MOS target provided by the present application;

[0043] FIG. 2 is an SEM diagram of the MOS target prepared in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0045] In the embodiments of the present application, the MOS target material refers to a metal oxide semiconductor target material, specifically an IGTO target material.

[0046] The first aspect of the embodiments of the present application provides a preparation method of a MOS target material, as shown in FIG. 1, including the following steps:

[0047] S01: performing a co-precipitation reaction on a mixed salt solution of three kinds of ions of In, Ga and Sn, a precipitating agent and a complexing agent, and obtaining high-purity indium gallium tin hydroxide colloid after washing and concentration;

[0048] S02: performing a hydrothermal reaction on the high-purity indium gallium tin hydroxide colloid and an additive, and obtaining first indium gallium tin oxide powder after washing and drying;

[0049] S03: performing calcination treatment on the first indium gallium tin oxide powder, and obtaining second indium gallium tin oxide powder;

[0050] S04: ball-mixing the second indium gallium tin oxide powder, a dispersing agent, an antifoaming agent and pure water, and obtaining slurry;

[0051] S05: performing slurry casting on the slurry, and obtaining a green body;

[0052] S06: performing sintering treatment on the green body under high-oxygen conditions, and obtaining a MOS target material.

[0053] The preparation method of the MOS target material provided by the embodiments of the present application can obtain first indium gallium tin oxide powder with uniform distribution of each component after performing a co-precipitation reaction on a mixed salt solution of three kinds of ions of In, Ga and Sn to obtain high-purity indium gallium tin hydroxide colloid and adding an additive to perform a hydrothermal reaction, and can make the first indium gallium tin oxide powder slightly lose oxygen. The powder particle size is increased through calcination, so as to facilitate forming, improve the density and strength of the green body, and thus help to provide target material density. Meanwhile, by controlling the calcination conditions, the oxygen content of the generated second indium gallium tin oxide powder can be more accurately controlled and kept slightly lost, and the loss of In2O3 to generate low-valence indium oxide (such as In2O or InO) during the sintering process of the green body is prevented, so as to affect the conductivity and oxygen content of the target material. Therefore, compared with the conventional air pressure sintering method of mixed indium oxide, gallium oxide and tin oxide powder, the sintering process of the present application is simple in reaction, good in uniformity of target material composition and organization, free of segregation, high in density and good in conductivity. Compared with the IGZO target material, the MOS target material of the present application does not contain ZnO, which can avoid the problem that ZnO is sensitive to temperature and water vapor and easily affects the electrical stability of the TFT during continuous operation, and on the other hand, Sn can increase the carrier concentration and improve the conductivity of the target material, and the ion radius of Sn 4+ is closer to that of In 3+ , and it is easier to form a high-mobility channel, so as to help to improve the mobility of the TFT.

[0054] The step S01 includes: adding indium salt, gallium salt and tin salt into pure water and stirring to obtain a mixed salt solution of In, Ga and Sn ions, in which the mass ratio of In, Ga and Sn 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.

[0055] In the embodiment, the temperature of the co-precipitation reaction is 50-65℃, the time is 6-8h, and the pH value is 8.5-9.5.

[0056] In the embodiment, the precipitant is selected from ammonia water or sodium hydroxide, and the complexing agent is selected from ammonium nitrate or ammonium chloride.

[0057] In the embodiment, the temperature of the hydrothermal reaction is 150-250℃, and the time is 12-24h. Under the hydrothermal condition, the additive has a reducing effect, so that the first indium gallium tin oxide powder is slightly deoxidized, which is beneficial to preventing In2O3 from being deoxidized to 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 improving the uniformity of the target material. In addition, through the hydrothermal reaction, hard agglomeration of the powder is avoided, the uniformity and dispersibility of the powder are improved, and the sintering activity of the powder is higher, so as to help improve the purity, uniformity and density of the MOS target material.

[0058] In the embodiment, the mass ratio of the high-purity indium gallium tin hydroxide colloid and the additive is (1-2):(0.01-0.05), in which the additive is selected from sucrose, glucose, fructose and the like.

[0059] In the embodiment, the primary particle size of the first indium gallium tin oxide powder is 0.05-0.1μm.

[0060] In the embodiment, the atmosphere of the calcination treatment is argon-hydrogen mixed gas with a volume ratio of argon to hydrogen being (95-99):(1-5), the temperature is 600-800℃, and the time is 4-10h. The calcination condition is beneficial to the growth of the first indium gallium tin oxide powder and the increase of the particle size, so as to facilitate the subsequent forming, and the oxygen content of the second indium gallium tin oxide powder generated can be more accurately controlled and slightly deoxidized.

[0061] In the embodiment, the mass ratio of In, Ga and Sn in the second indium gallium tin oxide powder is (34.7-67.4):(1.5-27.5):(13.0-16.5).

[0062] In the embodiment, the oxygen content of the second indium gallium tin oxide powder is less than that of the MOS target material, which is beneficial to prevent the second indium gallium tin oxide powder from losing oxygen to form In2O3, In2O or InO during the subsequent sintering process, thereby affecting the conductivity and density of the target material.

[0063] In the embodiment, the particle size of the second indium gallium tin oxide powder is 0.2-0.5 μm, which is beneficial to the slip casting of the powder and provides the density and strength of the green body.

[0064] In the embodiment, the step of mixing the second indium gallium tin oxide powder, the dispersant, the defoaming agent and the pure water in the ball mill includes: adding the second indium gallium tin oxide powder, the dispersant, the defoaming agent and the pure water into the ball mill tank, and ball milling at a speed of 200-1000 rpm for 6-18 h to obtain the slurry.

[0065] In the embodiment, the solid content of the slurry is 60-70%.

[0066] In the embodiment, the addition amount of the dispersant 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, cetyl sulfonate, polycarboxylate, polyacrylate or triethanolamine.

[0067] In the embodiment, the addition amount of the defoaming agent is 0.1-0.5% of the mass of the second indium gallium tin oxide powder. Specifically, the defoaming agent can be selected from polyether defoaming agent and / or high-carbon alcohol.

[0068] In the embodiment, the step of slip casting the slurry includes: loading the slurry into a vacuum tank, vacuum degassing, and then injecting the slurry into a sealed resin or graphite mold cavity at a pressure of 0.2-1.5 MPa until no water droplets come out of the mold, opening the mold, taking out the solidified body, and placing it at room temperature (20-25°C) for 24 h to obtain the green body.

[0069] In the embodiment, the step of sintering the green body under high-oxygen conditions includes: loading the green body into an alumina sleeve and placing it in a sintering furnace, then vacuumizing the alumina sleeve, and sintering the green body at a temperature of 1000-1200°C and a pressure of 0.1-0.5 MPa for 1-3 h. -2 ~10 -3Pa starts to pass oxygen and the oxygen pressure of the alumina sleeve is 0.05-0.1 MPa, and then the temperature is raised to 1400-1600 ℃ for 12-48 h. In this embodiment, the green body is placed in the alumina sleeve and then in the sintering furnace, so that the green body is sintered in a narrow space, which is beneficial to precisely control the uniformity of airflow and temperature, not only can slow down the heat exchange between the green body and the furnace, reduce the temperature fluctuation, make the green body heat more evenly, reduce the deformation or cracking caused by thermal stress, and improve the uniformity of the target material organization, but also can ensure that the sintering airflow field and temperature field of different production batches are the same, so that the performance of the target material produced is stable and has good repeatability. Moreover, by controlling the oxygen pressure of the alumina sleeve, the sintering of the green body under high oxygen conditions can help the slightly deoxidized second indium gallium tin oxide powder to be fully oxidized to form a target material with uniform composition and good electrical conductivity, preventing In2O3 in the powder from deoxidizing to form In2O or InO and affecting the electrical conductivity and density of the target material. In addition, through the alumina sleeve, the amount of oxygen used can be reduced, and the cost can be reduced.

[0070] In the embodiment, the relative density of the MOS target material is ≥98.5%, and the resistivity is ≤10 mΩ·cm.

[0071] The second aspect of the embodiment of the present application provides a MOS target material, which is prepared by the preparation method of the MOS target material provided by the present application.

[0072] The MOS target material provided by the embodiment of the present application has the advantages of high density, good uniformity of composition and organization, low resistivity, and good stability, because it is prepared by the preparation method of the MOS target material provided by the embodiment of the present application.

[0073] The third aspect of the embodiment of the present application provides a thin film transistor, which comprises an active layer film obtained by sputtering a MOS target material provided by the present application.

[0074] The thin film transistor provided by the embodiment of the present application has the advantages of low resistivity, high carrier concentration, and high mobility, and good stability to water, oxygen, light, and heat, because the active layer film thereof is obtained by sputtering a metal oxide semiconductor target material provided by the embodiment of the present application. Therefore, the performance indicators such as the mobility, threshold voltage, and current switching ratio of the TFT can be improved, the reliability problem that the TFT is prone to occur after long-time work can be improved, and the service life of the TFT can be improved, thereby helping to realize high resolution, high refresh rate, low power consumption, and high definition of the display screen, and improve the stability of the display screen.

[0075] The following will be described in conjunction with specific embodiments.

[0076] Embodiment 1

[0077] The embodiment provides a preparation method of a MOS target material, comprising the following steps:

[0078] S11: according to the mass ratio of In, Ga and Sn being 37.6:27.5:14.3, a proper amount of InCl3 powder, GaCl3 powder and SnCl4*5H2O are weighed and added into pure water to be stirred uniformly to obtain a mixed salt solution of In, Ga and Sn ions; the mixed salt solution of In, Ga and Sn ions, a sodium hydroxide solution and an ammonia solution are added into a reaction kettle to be mixed, the temperature of the reaction kettle is controlled to be 60 DEG C, the pH value of the reaction system is 9, and a coprecipitation reaction is carried out for 7h, and after being cleaned and concentrated, high-purity indium gallium tin hydroxide colloid is obtained;

[0079] S12: according to the mass ratio being 1.5:0.03, a proper amount of high-purity indium gallium tin hydroxide colloid and glucose are weighed and added into pure water to be stirred uniformly to obtain a suspension (the concentration is 0.5mol / L); the suspension is transferred into the inner container of the reaction kettle, and a proper amount of pure water is added, so that the final volume of the suspension is 70% of the volume of the inner container of the reaction kettle, the reaction kettle is put into a drying box at 200 DEG C, and a hydrothermal reaction is carried out for 18h, and then the precipitate obtained through centrifugal separation is repeatedly cleaned by using pure water and anhydrous ethanol, and after being dried, a first indium gallium tin oxide powder (the average particle size D50 is 0.08um) is obtained;

[0080] S13: the first indium gallium tin oxide powder is placed in an atmosphere sintering furnace, vacuumized to 10 -2 Pa, argon-hydrogen mixed gas (the volume ratio of argon to hydrogen is 98:2) is introduced, the temperature is increased to 750 DEG C, and heat treatment is carried out for 6h, and a second indium gallium tin oxide powder (the average particle size D50 is 0.35um) is obtained;

[0081] S14: the second indium gallium tin oxide powder, polyethylene glycol, polyoxypropylene glycerol ether and pure water are added into a ball mill tank, and ball milling is carried out at a rotating speed of 500rpm for 12h to obtain a slurry (the solid content is 65%); the adding amount of polyethylene glycol is 0.5% of the mass of the second indium gallium tin oxide powder, and the adding amount of polyoxypropylene glycerol ether is 0.3% of the mass of the second indium gallium tin oxide powder;

[0082] S15: the slurry is loaded into a vacuum tank, after vacuum defoaming, the slurry is injected into a sealed graphite mold cavity at a pressure of 1MPa until no water drops come out of the mold, the mold is opened, the solidified blank is taken out, and the blank is placed at room temperature for 24h to obtain a green body.

[0083] S16: the green body is loaded into an alumina sleeve and then placed in a sintering furnace, vacuumization is carried out on the alumina sleeve, the vacuum degree is 5*10 -2When the pressure is 0.08 MPa, oxygen is introduced at the time of t0, and then the temperature is raised to 1500 DEG C for sintering for 36 hours to obtain the MOS target material.

[0084] Comparative Example 1

[0085] The present comparative example provides a preparation method of a MOS target material, which is different from the example 1 in that:

[0086] Step S12 is not performed;

[0087] In step S13, the high-purity indium gallium tin hydroxide colloid is placed in a sintering furnace, and then the temperature is raised to 750 DEG C under an air atmosphere for calcination for 6 hours to obtain the second indium gallium tin oxide powder (the average particle size D50 is 0.41 μm).

[0088] Comparative Example 2

[0089] The present comparative example provides a preparation method of a MOS target material, which is different from the example 1 in that:

[0090] Step S13 is not performed;

[0091] In step S14, the first indium gallium tin oxide powder, polyethylene glycol, polyoxypropylene glycerol ether and pure water are added into a ball mill pot.

[0092] Comparative Example 3

[0093] The present comparative example provides a preparation method of a MOS target material, which is different from the example 1 in that:

[0094] In step S15, the green body is placed in a sintering furnace, and then the sintering furnace is vacuumized, and the vacuum degree is 5x10 -2 Pa, oxygen is introduced, and then the temperature is raised to 1500 DEG C for sintering for 36 hours to obtain the MOS target material.

[0095] Comparative Example 4

[0096] The present comparative example provides a preparation method of a MOS target material, which comprises the following steps:

[0097] S1: according to the mass ratio of indium, gallium and tin of 37.6:27.5:14.3, the appropriate amount of indium oxide powder, gallium oxide powder and tin oxide powder are weighed;

[0098] S2: the indium oxide powder, gallium oxide powder and tin oxide powder, polyethylene glycol, polyoxypropylene glycerol ether and pure water are added into a ball mill pot, and ball milling is performed at a speed of 500 rpm for 12 hours to obtain a slurry;

[0099] S3: The slurry was loaded into a vacuum tank, and after vacuum degassing, the slurry was injected into a sealed graphite mold cavity at a pressure of 1 MPa until no water droplets came out of the mold, the mold was opened, the solidified blank was taken out, and was left to stand at room temperature for 24 h to obtain a green body;

[0100] S4: The green body was placed in a sintering furnace, and then the sintering furnace was vacuumized to a vacuum degree of 5 x 10 -2 Pa, oxygen was introduced, and then the temperature was raised to 1500°C for heat preservation sintering for 36 h to obtain the MOS target material.

[0101] Related performance test analysis:

[0102] 1. After the MOS target material was plastic encapsulated, the density of the MOS target material prepared in Example 1 and Comparative Examples 1-4 was tested by using the Archimedes test density method; specifically, the MOS target material was evenly cut into 5 sections along the cross section, and then the actual density of each section was tested, and the relative density was calculated based on the theoretical density, i.e. relative density = actual density / theoretical density x 100%; the test results are shown in Table 1 below;

[0103] 2. The resistivity of the MOS target material prepared in Example 1 and Comparative Examples 1-4 was tested by using a four-probe tester; specifically, the resistivity of 5 different regions of the MOS target material was tested; the test results are shown in Table 2 below;

[0104] 3. The O content of the MOS target material prepared in Example 1 and Comparative Examples 1-4 was tested by using an oxygen-nitrogen analyzer; specifically, 5 samples were cut from different regions of the MOS target material, and then the O content of each sample was tested; the test results are shown in Table 3 below;

[0105] The median uniformity = [(max-min) / (max+min)] x 100%.

[0106] Table 1

[0107] Table 2

[0108] Table 3

[0109] As can be seen from Tables 1-2, 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, which indicates that the preparation method of the present application can prepare a MOS target material with high density and low resistivity.

[0110] The relative density of the target material prepared in Example 1 is obviously 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 obviously smaller than that of Comparative Examples 3 and 4, which is mainly due to the fact that the green body is placed in the alumina sleeve for high-oxygen sintering in the present application, the uniformity of airflow and temperature can be accurately controlled, the green body is uniformly heated, thereby helping to improve the density and microstructure uniformity of the target material, and the density distribution is more uniform.

[0111] The relative density of Comparative Example 1 is smaller than that of Example 1, which is mainly due to the fact that the high-purity indium gallium tin hydroxide colloid generated by the coprecipitation reaction is directly air calcined in Comparative Example 1, the oxygen content of the indium gallium tin oxide powder cannot be controlled, In2O3 loses oxygen and leaves gaps during subsequent sintering, thereby being not conducive to the formation of a high-density target material. The relative density of Comparative Example 2 is smaller than that of Example 1, which is mainly due to the fact that the powder prepared by hydrothermal reaction in Comparative Example 2 is too fine, which is not conducive to slip casting, thereby being not conducive to the formation of a high-density target material.

[0112] The resistivity and the median uniformity of the resistivity of the target material prepared in Example 1 are obviously smaller than those of Comparative Examples 1-2 and Comparative Example 4, which is mainly due to the fact that the coprecipitation reaction, the hydrothermal reaction and the calcination are combined in the present application, the first indium gallium tin oxide powder is slightly deoxygenated by adding glucose and the high-purity indium gallium tin hydroxide colloid for hydrothermal reaction, the second indium gallium tin oxide powder is further calcined in an argon-hydrogen mixed atmosphere, the oxygen content of the powder can be more accurately controlled and slightly deoxygenated, thereby being fully oxidized to stable In2O3 during subsequent high-oxygen sintering, avoiding the influence of doped low-valence indium oxides (such as InO or In2O) on the conductivity, and thus the resistivity of the target material is lower.

[0113] The resistivity and the median uniformity of the resistivity of the target material prepared in Example 1 are smaller than those of Comparative Example 3, which is mainly due to the fact that the green body is placed in the alumina sleeve and then sintered in the sintering furnace in the present application, the temperature and airflow can be accurately controlled, the green body is more uniformly heated, and thus the composition and microstructure of the target material are uniform, and the resistivity is small.

[0114] As can be seen from Table 3, 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 small, while the oxygen content of each region of the target material prepared in Comparative Examples 1-2 is obviously smaller than the theoretical value, and the median uniformity of the oxygen content is large, which is mainly due to the fact that the coprecipitation reaction, the hydrothermal reaction and the calcination are combined in the present application, the oxygen content of the second indium gallium tin oxide powder is accurately controlled and slightly deoxygenated, which can reduce the deoxygenation of In2O3 during high-oxygen sintering of the green body and affect the oxygen content of the target material.

[0115] As can be seen from the SEM of FIG. 2, the MOS target material prepared in Example 1 has uniform grains, the grains are tightly bonded, and there are no obvious grain boundaries and pores.

[0116] It can be seen that the MOS target material prepared by the preparation method of the MOS target material provided in the embodiments of the present application has good uniformity, high density, good electrical conductivity and stable electrical performance, and the MOS thin film prepared by sputtering the MOS target material has good uniformity, high carrier concentration and high mobility, and does not contain ZnO, and has good stability to water, oxygen, light and heat.

[0117] The above merely provides the preferred embodiments of the present application, but is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall fall within the scope of the present application.

Claims

1. A method for preparing a MOS target, characterized in that, Includes the following steps: A co-precipitation reaction was carried out with a mixed salt solution of In, Ga, and Sn ions, a precipitant, and a complexing agent. After washing and concentration, a high-purity indium gallium tin hydroxide colloid was obtained. After the high-purity indium gallium tin hydroxide colloid and additives are subjected to a hydrothermal reaction, the first indium gallium tin oxide powder is obtained by washing and drying. The first indium gallium tin oxide powder is calcined to obtain the second indium gallium tin oxide powder; The second indium gallium tin oxide powder, dispersant, defoamer, and pure water are ball-milled and mixed to obtain a slurry; The slurry is then poured into molds to obtain a raw blank; The raw 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 must be 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 to 0.5 μm.

3. The preparation method according to claim 1, characterized in that, At least one of the following conditions must be met: The steps for preparing a mixed salt solution of In, Ga, and Sn ions include: adding indium salt, gallium salt, and tin salt to pure water and stirring until homogeneous to obtain a mixed salt solution of In, Ga, and Sn ions; The coprecipitation reaction was carried out at a temperature of 50–65°C for 6–8 hours, with a pH value of 8.5–9.

5. The precipitant is selected from ammonia 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 hydrothermal reaction is carried out at a temperature of 150–250°C for 12–24 hours.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the high-purity indium gallium tin hydroxide colloid to the additive is (1-2):(0.01-0.05).

6. The preparation method according to claim 1, characterized in that, The adjuvant is selected from any one of sucrose, glucose, or fructose.

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

8. 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).

9. The preparation method according to claim 1, characterized in that, The solid content of the slurry is 60-70%.

10. The preparation method according to claim 1, characterized in that, The amount of dispersant added is 0.1% to 1% of the mass of the second indium gallium tin oxide powder; And / or, the amount of the defoamer added is 0.1 to 0.5% of the mass of the second indium gallium tin oxide powder.

11. The preparation method according to claim 1, characterized in that, The dispersant is selected from at least one of polyethylene glycol, hexadecyl sulfonate, polycarboxylate, polyacrylate, or triethanolamine; And / or, the defoamer is selected from polyether defoamers and / or higher alcohols.

12. The preparation method according to any one of claims 1 to 11, characterized in that, The step of sintering the green blank under high oxygen conditions includes: The green blank is loaded into an alumina sleeve and placed in a sintering furnace. Then, the alumina sleeve is evacuated to a vacuum degree of 10. -2 ~10 -3 Oxygen is introduced at a pressure of 0.05–0.1 MPa to maintain the oxygen pressure in the alumina sleeve at 1400–1600 °C for sintering at this temperature for 12–48 hours.

13. The preparation method according to claim 12, characterized in that, The relative density of the MOS target is ≥98.5%, and the resistivity is ≤10mΩ·cm.

14. A MOS target, characterized in that, The MOS target prepared by the method described in any one of claims 1 to 13 includes the MOS target prepared by the method described in any one of claims 1 to 13.

15. A thin-film transistor, comprising an active thin film layer, characterized in that, The active layer thin film is obtained by sputtering the MOS target as described in claim 14.

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