Oxide sintered body, method for producing the same, oxide target, and application thereof

Abstract

The application discloses an oxide sintered body and a preparation method thereof, an oxide target material and application, and relates to the technical field of semiconductors. By introducing rare earth oxides and a second metal compound into an indium oxide sintered body, the second metal compound being a metal oxide and / or a metal fluoride, on the one hand, a coupling electron channel can be formed with the indium electron orbit of the indium oxide, the characteristics of a thin film made of the sintered body can be improved, and the performance of a device can be improved; on the other hand, the rare earth oxides form small crystal grains embedded in the gaps of the main body material crystal grains, a dense sintered body is formed, and therefore a highly dense ceramic target material can be obtained. The oxide sintered body provided by the application can obtain a sintered body or a target material with high density by optimizing the composition and the preparation method, and is beneficial to making the grain size controllable and the distribution controllable.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to an oxide sintered body, its preparation method, an oxide target material, and its applications. Background Technology

[0002] With the increasing demand for liquid crystal display panels, oxide sputtering targets, as one of the key technologies for liquid crystal display panels, has become a research hotspot. Thin films obtained by sputtering using targets such as indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and indium gallium zinc oxide (IGZO) can be used as the semiconductor active layer of thin-film transistors (TFTs) and can be applied in LCDs, OLEDs, and electronic paper flat panel displays (FPDs), exhibiting excellent characteristics.

[0003] As the core active semiconductor layer material in TFTs, oxide targets have stringent requirements regarding their properties. The density, grain size, composition, and uniformity of the microstructure of the target material affect various electrical and optical properties of the deposited thin film, and its quality determines the characteristics of the display panel. Currently, oxide targets face two main challenges. First, their formulations urgently need upgrading. New technologies and products place higher demands on the properties of oxide semiconductor materials, requiring upgrades and iterations of material formulations to meet the needs of higher-end products. Second, the quality of oxide targets also needs further improvement. Optimization and upgrading of various target performance indicators are necessary, especially for high-end product formulations, which require specific designs and solutions to meet the industrialization needs of related products. These include: improving target density, controlling target grain size distribution, controlling target resistivity distribution, and adjusting target mechanical strength, among other things.

[0004] Therefore, there is an urgent need to prepare oxide targets with controllable grain size and uniform and controllable resistivity distribution in order to improve the photoelectric properties of the materials and achieve the control of the properties of the thin films prepared from them.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an oxide sintered body and its preparation method, an oxide target material and its application, with the aim of preparing an oxide target material with controllable grain size and uniform and controllable resistivity distribution.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides an oxide sintered body comprising a first metal compound, a rare earth oxide, and a second metal compound; wherein the first metal compound is indium oxide, and the second metal compound is selected from at least one of metal oxides and metal fluorides.

[0009] In oxide sintered bodies, the molar percentages of indium, rare earth elements, and other metal elements in the total metal elements of the sintered body are (10%–98%), (0.1%–8%), and (1%–88%), respectively.

[0010] In an optional embodiment, the rare earth oxide is selected from at least one of cerium oxide, praseodymium oxide, samarium oxide, europium oxide, terbium oxide, and thulium oxide;

[0011] Preferably, the rare earth oxide is selected from at least one of cerium oxide, praseodymium oxide, and terbium oxide;

[0012] Preferably, the rare earth elements in the oxide sintered body have two valence states, and the proportion of high valence ions in the same rare earth element to the total number of ions is 20% to 60%.

[0013] In an optional embodiment, the metal oxide is selected from at least one of zinc oxide, tin oxide, gallium oxide, tantalum oxide, titanium oxide, aluminum oxide, antimony oxide, bismuth oxide, and hafnium oxide; preferably, the metal oxide is selected from at least one of zinc oxide, tin oxide, and gallium oxide.

[0014] In an optional embodiment, the metal fluoride is selected from at least one of tin fluoride, zinc fluoride, gallium fluoride, vanadium fluoride, praseodymium fluoride, and terbium fluoride; preferably, the metal fluoride is selected from at least one of praseodymium fluoride and terbium fluoride.

[0015] Preferably, the resistivity of the oxide sintered body is 0.01 to 30 mΩ·cm, and the relative density is greater than 98.0%; more preferably, the resistivity of the oxide sintered body is 0.1 to 10 mΩ·cm, and the relative density is greater than 99.0%.

[0016] Preferably, the grain size in the oxide sintered body is less than 10 μm, and the proportion of grains with a grain size of 2 μm to 6 μm is greater than 80%.

[0017] Preferably, the oxide sintered body contains at least two crystalline phases.

[0018] In a second aspect, the present invention provides a method for preparing an oxide sintered body according to any of the foregoing embodiments, comprising: preparing an oxide sintered body using indium oxide, rare earth oxides, and a second metal compound as raw materials.

[0019] In an optional embodiment, the raw materials are pretreated to obtain a mixed powder with a particle size that meets the requirements, the mixed powder is granulated to obtain a granulated powder, the granulated powder is pressed into a sintered green body, and the sintered green body is sintered.

[0020] Preferably, the sintered green body is first dried and degreased before sintering;

[0021] Preferably, the sintering process includes: sintering at a first sintering temperature and a second sintering temperature, respectively, wherein the first sintering temperature is 1000℃~1400℃ and the holding time is t1; the second sintering temperature is 1450℃~1600℃ and the holding time is t2; and the percentage value of t1 / (t1+t2) is 85%~98%.

[0022] In an optional embodiment, the particle sizes of indium oxide, rare earth oxide, and second metal compound in the raw materials satisfy the following: particle size of indium oxide > particle size of second metal compound > particle size of rare earth oxide.

[0023] Preferably, the mixed powder satisfies D50 = 0.10 μm ~ 1.15 μm, D10 ≥ 0.05 μm, D90 ≤ 2.0 μm, and the particle size distribution coefficient of the mixed powder is P = (D90 - D10) / D50, P ≤ 2.0;

[0024] Preferably, the pretreatment process includes wet ball milling and wet grinding performed sequentially;

[0025] Preferably, the slurry after wet grinding is subjected to vacuum defoaming treatment before granulation;

[0026] Preferably, spray granulation is used to granulate the powder, and the average particle size of the granulated powder is controlled to be 20 μm to 65 μm; more preferably, the granulated powder is sieved to obtain particles with a particle size of 25 μm to 50 μm.

[0027] More preferably, the sieved powder is first activated and then pressed into a sintered green body. The activation method is to irradiate with an ultraviolet wavelength of 100nm to 400nm.

[0028] Thirdly, the present invention provides an oxide target material, which is prepared by any of the oxide sintered bodies in the foregoing embodiments or by any of the preparation methods in the foregoing embodiments.

[0029] Preferably, the oxide target is a planar target or a rotating target.

[0030] Fourthly, the present invention provides an oxide semiconductor thin film prepared using the oxide target material described in the foregoing embodiments.

[0031] Fifthly, the present invention provides a thin film device comprising the oxide semiconductor thin film of the foregoing embodiments.

[0032] This invention offers the following advantages: By introducing rare earth oxides and a second metal compound into the indium oxide sintered body, where the second metal oxide is a metal oxide and / or a metal fluoride, it can, on the one hand, form a coupling electron channel with the indium electron orbitals of indium oxide, improving the characteristics of the fabricated thin film and enhancing device performance; on the other hand, the rare earth oxides form micrograins that embed into the gaps between the grains of the host material, forming a dense sintered body, thereby obtaining a highly dense ceramic target. The oxide sintered body provided by this invention, through optimized composition, can yield a highly dense sintered body or target, which is beneficial for controllable grain size and distribution. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 Electron microscope characterization image of the target material prepared in Example 1;

[0035] Figure 2 A grain size diagram of the target material was prepared for Example 1;

[0036] Figure 3 Electron microscope characterization image of the target material prepared in Example 2;

[0037] Figure 4 This is a grain size diagram of the target material prepared in Example 2;

[0038] Figure 5 Electron microscope characterization image of the target material prepared in Example 5;

[0039] Figure 6 This is a grain size diagram of the target material prepared in Example 5;

[0040] Figure 7 The electron microscope characterization image of the target material obtained in Example 13;

[0041] Figure 8 The image shows the appearance of the target material obtained in Experiment ① of Example 14;

[0042] Figure 9 The image shows the appearance of the target material obtained in Experiment ② of Example 14;

[0043] Figure 10 The electron microscope characterization image of the target material obtained in Example 15 without sintering at the second sintering temperature is shown.

[0044] Figure 11 The electron microscope characterization image of the target material was obtained when the proportion of the first sintering temperature range in Example 15 was approximately 76.9%.

[0045] Figure 12 The electron microscope characterization image of the target material obtained in Example 16;

[0046] Figure 13 The results of X-ray photoelectron spectroscopy (XPS) measurements of the targets in Examples 1 and 5 are shown in the figure. Figure 13 In the text, (a) represents the target material of Example 1; (b) represents the target material of Example 5;

[0047] Figure 14 This is a structural diagram of a thin-film transistor device;

[0048] Figure 15 The figures show thin-film transistor devices fabricated from targets without rare earth elements and with rare earth elements, as shown in Comparative Example 1. (a) represents the device without rare earth elements; (b) represents the device with rare earth elements.

[0049] Icons: 01-Substrate; 02-Gate; 03-Gate insulating layer; 04-Active layer; 06-Source; 07-Drain; 08-Buffer layer; 09-Spacer layer. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0051] This invention provides a method for preparing oxide sintered bodies, using indium oxide, rare earth oxides, and second metal compounds as raw materials. By optimizing the composition of the oxide sintered body, the density of the product is improved, which is beneficial for obtaining highly dense ceramic targets. The specific steps are as follows:

[0052] S1. Material preparation

[0053] A first metal compound, a rare earth oxide, and a second metal compound are prepared as raw materials. The first metal compound is indium oxide. The second metal compound is selected from at least one of a metal oxide and a metal fluoride, and can be a metal oxide or a metal fluoride, or a combination of both. The raw materials of the first metal compound, the rare earth oxide, and the second metal compound are powders, which facilitates the preparation of mixed powders with the required particle size after pretreatment.

[0054] In some embodiments, the rare earth oxide is selected from at least one of cerium oxide, praseodymium oxide, samarium oxide, europium oxide, terbium oxide, and thulium oxide, and may be any one or more of the above. Preferably, the rare earth oxide is selected from at least one of cerium oxide, praseodymium oxide, and terbium oxide. By selecting the type of rare earth oxide, a coupling electron channel can be formed with the indium electron orbitals of indium oxide, improving the properties of the thin film produced. The above rare earth oxides can form micrograins that can be embedded in the gaps between the grains of the host material to form a dense sintered body, thereby obtaining a highly dense ceramic target.

[0055] In some embodiments, the metal oxide is selected from at least one of zinc oxide, tin oxide, gallium oxide, tantalum oxide, titanium oxide, aluminum oxide, antimony oxide, bismuth oxide, and hafnium oxide, and may be any one or more of the above. Preferably, the metal oxide is selected from at least one of zinc oxide, tin oxide, and gallium oxide. Optimizing the type of metal oxide can further improve the density of the product, which is beneficial for obtaining a product with controllable grain size and uniform and controllable resistivity distribution.

[0056] In some embodiments, the metal fluoride is selected from at least one of tin fluoride, zinc fluoride, gallium fluoride, vanadium fluoride, praseodymium fluoride, and terbium fluoride, and may be any one or more of the above. Preferably, the metal fluoride is selected from at least one of praseodymium fluoride and terbium fluoride. By optimizing the type of metal fluoride, the grain size distribution and resistivity distribution of the sintered body can be further improved, thereby enhancing device performance.

[0057] Furthermore, by adjusting the ratio of indium oxide, rare earth oxides, and the second metal compound, the molar percentages of indium, rare earth elements, and other metal elements in the total metal elements of the sintered body are satisfied to be (10%–98%), (0.1%–8%), and (1%–88%), respectively. The amounts of indium oxide, rare earth oxides, and the second metal compound should preferably be controlled within the above ranges to further improve the grain size distribution and resistivity distribution of the sintered body. Specifically, the molar percentage of indium can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, etc., the molar percentage of rare earth elements can be 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, etc., and the molar percentage of the total of other metallic elements can be 1%, 3%, 5%, 8%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 88%, etc.

[0058] In some embodiments, the particle sizes of indium oxide, rare earth oxide, and the second metal compound in the raw materials satisfy the following: particle size of indium oxide > particle size of the second metal compound > particle size of rare earth oxide. By controlling the particle size of indium oxide to be the largest and the particle size of rare earth oxide to be the smallest, it is beneficial to enable the rare earth oxide to form micro-grains that can be embedded in the gaps between the grains of the main material to form a dense sintered body, thereby obtaining a highly dense ceramic target material.

[0059] In addition, some sintering processes include the addition of sintering aids, preferably containing 100 to 10,000 ppm of at least one element selected from tin, tantalum, germanium, silicon, titanium, zirconium, and hafnium. The presence of these elements is beneficial for increasing the density, strength, resistivity, color deviation, and uniformity of the target material, as well as reducing target cracking and abnormal discharge, and can be expected to improve the quality of semiconductor targets.

[0060] S2, Preprocessing

[0061] The raw materials are pretreated to obtain mixed powder with a particle size that meets the requirements. The pretreatment method is not limited. If the particle size of the raw materials is already ideal, pretreatment may not be necessary.

[0062] In some embodiments, the pretreatment process includes sequential wet ball milling and wet sand milling. First, wet ball milling is performed to break large-diameter particles into small-diameter particles, and then wet sand milling is used to process them into even smaller-diameter particles so that the particle size of the mixed powder meets the requirements.

[0063] Furthermore, the mixed powder should satisfy the following conditions: D50 = 0.10 μm to 1.15 μm, D10 ≥ 0.05 μm, and D90 ≤ 2.0 μm. The particle size distribution of the mixed powder should ideally meet these requirements to ensure that the grain distribution of the prepared sintered body meets the requirements. Simultaneously, the particle size distribution coefficient P of the mixed powder is defined as (D90 - D10) / D50, and P should satisfy: P ≤ 2.0. The value of P, combined with the ranges of D50, D10, and D90, allows for more controllable grain size distribution in the prepared sintered body.

[0064] Specifically, the D50 of the mixed powder can be 0.10μm, 0.30μm, 0.50μm, 0.80μm, 0.90μm, 1.00μm, 1.10μm, 1.15μm, etc., the D10 can be 0.05μm, 0.08μm, 0.10μm, 0.20μm, etc., and the D90 can be 2.0μm, 1.0μm, 0.5μm, etc.

[0065] In some embodiments, the wet-milled slurry can be first subjected to vacuum degassing treatment before the subsequent granulation process, in order to reduce the defect rate of the granulated powder, improve the yield of the granulated powder, and thus improve the density of the target material.

[0066] S3, Granulation and Activation

[0067] The mixed powder is granulated to obtain granulated powder. The granulation method is not limited, and spray granulation can be used to obtain particles of the required specific size and requirements.

[0068] Furthermore, controlling the average particle size of the granulated powder obtained after spray granulation to be 20μm to 65μm is beneficial for obtaining a more dense sintered body after subsequent sintering. The granulated powder can be sieved to obtain particles with a particle size of 25μm to 50μm, making the particle size more uniform before entering the sintering stage.

[0069] Specifically, the average particle size of the granulated powder obtained after spray granulation can be 20μm, 30μm, 40μm, 50μm, 60μm, 65μm, etc.

[0070] In a preferred embodiment, the sieved powder is first activated and then pressed into a sintered green body. The activation method is selected from at least one of microwave treatment and light treatment. Any one or more of the above methods can be used for activation.

[0071] Specifically, microwave treatment involves placing powder in a microwave device (such as a microwave oven) for processing. Microwave treatment helps to further remove moisture from the powder particles, and the heat absorption process can repair the morphology of irregular particles, making them more likely to take on a regular spherical shape. It also increases the particle mobility during the pressing and forming process, which is conducive to the formation of a dense sintered body.

[0072] Specifically, phototreatment utilizes ultraviolet (UV) light to irradiate powder, altering the surface energy and surface states of the particles, removing organic solvents from the particle surface, and increasing particle mobility during pressing and molding, thus promoting the formation of a dense sintered body. UV irradiation in the 100nm–400nm wavelength range can be used, with the UV light intensity controlled at 5mW / cm². 2 ~90mW / cm 2 The processing time is 5 to 40 minutes.

[0073] S4, pressing and sintering

[0074] Pressing granulated powder into sintered green bodies and then sintering the green bodies, pressing and then sintering again, helps to further improve the density of the sintered body.

[0075] In some embodiments, the sintered green body can be dried and degreased before sintering. Drying removes some moisture, and degreasing removes organic solvents, improving the quality of the sintered product. Existing degreasing methods can be used for degreasing, and the specific operation process will not be described in detail here.

[0076] Furthermore, the sintering process can be carried out at two sintering temperatures, namely a first sintering temperature and a second sintering temperature. The first sintering temperature is 1000℃~1400℃, with a holding time of t1; the second sintering temperature is 1450℃~1600℃, with a holding time of t2. Most of the sintering time is spent at the first sintering temperature to prevent excessively high sintering temperatures from affecting the performance of the sintered body, thus facilitating the acquisition of a target material with more ideal performance while ensuring density. The percentage value of t1 / (t1+t2) is preferably 85%~98%, and t1+t2 is preferably controlled at 80h~110h. Longer sintering time helps to further improve the density and grain distribution of the sintered body.

[0077] Specifically, the first sintering temperature can be 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, etc., and the second sintering temperature can be 1450℃, 1480℃, 1500℃, 1520℃, 1550℃, 1580℃, 1600℃, etc. The total sintering time can be 80h, 85h, 90h, 95h, 100h, 105h, 110h, etc., and the holding time at the first sintering temperature can account for 80%, 85%, 90%, 95%, 98%, etc., specifically 64h to 104.5h.

[0078] Furthermore, after sintering is completed, it can be further processed into target material, as well as subsequent bonding and cleaning processes.

[0079] This invention also provides an oxide sintered body containing a first metal compound, a rare earth oxide, and a second metal compound. The first metal compound is indium oxide, and the second metal compound is selected from at least one of metal oxides and metal fluorides, with specific types as described above. The molar percentages of indium, rare earth elements, and other metal elements in the total metal elements of the sintered body are (10%–98%), (0.1%–8%), and (1%–88%), respectively. By optimizing the composition of the oxide sintered body, on the one hand, it can form a coupled electron channel with the indium electron orbitals of indium oxide, improving the thin film properties and enhancing device performance; on the other hand, the rare earth oxide forms micrograins that embed into the gaps between the grains of the host material, forming a dense sintered body, thereby obtaining a highly dense ceramic target.

[0080] Furthermore, the rare earth elements in the oxide sintered body prepared by the method in this embodiment of the invention have two valence states, and the proportion of high-valence ions in the same rare earth element is 20% to 60% of the total number of ions, such as 20%, 30%, 40%, 50%, 60%, etc. The resistivity of the oxide sintered body is 0.01 to 30 mΩ·cm, and the relative density is greater than 98.0%; preferably, the resistivity of the oxide sintered body is 0.1 to 10 mΩ·cm, and the relative density is greater than 99.0%. The prepared oxide sintered body contains at least two crystalline phases. The resistivity and relative density of the prepared oxide sintered body are within the above ranges, the resistivity distribution is uniform, and the product is relatively dense.

[0081] Furthermore, the oxide sintered body prepared by the method in the embodiments of the present invention has a grain size of less than 10 μm, and the proportion of grains with a grain size of 2 μm to 6 μm is greater than 80%. The grain size distribution of the prepared oxide sintered body is controllable and relatively uniform, which is beneficial to fundamentally improve the photoelectric properties of the material, realize the control of the properties of the prepared thin film, and ensure the repeatability and mass production of the material.

[0082] This invention also provides an oxide target material, which is prepared by the above-mentioned oxide sintered body. The oxide sintered body is processed to obtain a target material of the required size and shape, which can be a planar target material or a rotating target material.

[0083] This invention also provides an oxide semiconductor thin film, prepared using the aforementioned oxide target. The film can be prepared via physical vapor deposition using this oxide target, and the film thickness is not limited. By optimizing the composition and preparation process of the oxide target, such as by introducing an activation treatment step, a target with controllable grain size and uniformly controllable resistivity distribution can be obtained, fundamentally improving the photoelectric properties of the thin film material. This oxide semiconductor thin film can also be further used to prepare thin-film devices, such as thin-film transistors.

[0084] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0085] Example 1

[0086] This embodiment provides a method for preparing an oxide sintered body, the specific steps of which are as follows:

[0087] (1) Material preparation

[0088] Indium oxide, rare earth oxides, and a second metal compound were used as raw materials. The rare earth oxide was praseodymium oxide, and the second metal compound was a combination of zinc oxide and gallium oxide. The molar ratios of the oxides were prepared according to the molar ratios of indium, praseodymium, zinc, and gallium in Table 1. The powders of indium oxide, gallium oxide, zinc oxide, and rare earth oxide were weighed according to the molar ratios of each metal atom in Table 1, with a total weight of 3 kg. The average particle size of the indium oxide powder was 2.8 μm, the average particle size of the zinc oxide powder was 0.9 μm, the average particle size of the gallium oxide powder was 2.1 μm, and the average particle size of the praseodymium oxide powder was 0.5 μm.

[0089] (2) Preprocessing

[0090] Indium oxide powder, polyvinylpyrrolidone (PVP), and pure water were premixed, with PPVP comprising 1.5% of the total mass of the mixture. The solid content of the premixed solution was 50%. The mixture was pre-dispersed for 30 minutes and then ground into a first slurry using a sand mill at 850 rpm for 20 hours. The average particle size of the mixed powder in the first slurry was less than 0.3 μm, and the mixture was defoamed under vacuum.

[0091] Gallium oxide, zinc oxide, polyvinylpyrrolidone (PVP), and pure water were premixed, with PPVP comprising 1.2% of the total mass of the mixture. The solid content of the premixed solution was 50%. The mixture was ultrasonically pre-dispersed for 30 minutes and then ground into a second slurry using a sand mill at 900 rpm for 20 hours. The average particle size of the mixed powder in the second slurry was less than 0.3 μm, and the mixture was defoamed under vacuum.

[0092] The first slurry, the second slurry, praseodymium oxide, polyvinyl alcohol, and polyethylene glycol were mixed, with polyvinyl alcohol and polyethylene glycol each accounting for 1.0% of the total mass of the mixture. The solid content of the mixed slurry was 43%. The mixture was ground using a sand mill for 5 hours, resulting in a final slurry with an average particle size of less than 0.3 μm. The mixture was then defoamed under vacuum.

[0093] The particle size of the dried powder meets the following requirements: D50 = 0.25~0.35μm, D10 ≥ 0.1μm, D90 ≤ 0.8μm, and the particle size distribution coefficient P = (D90-D10) / D50 = 1.2.

[0094] (3) Granulation and activation

[0095] The slurry obtained in step (2) is spray granulated at a temperature of 200°C and a feed rate of 10 rpm. The average particle size of the powder after spray granulation is 20-65 μm. The granulated powder is then sieved to obtain particles with a particle size of 20-35 μm.

[0096] The screened powder particles were activated by irradiation with ultraviolet light for a period of time, as follows: The screened powder was subjected to a treatment process of irradiation with ultraviolet light at a wavelength of 365nm and an intensity of 80mW / cm². 2 The processing time is 30 minutes. The continuous movement of the powder ensures that all particles receive uniform irradiation. After the first stage of processing, the powder is then subjected to a second ultraviolet (UV) irradiation treatment with a wavelength of 172 nm and a UV intensity of 5 mW / cm². 2 The processing time is 10 minutes. Similarly, the powder remains in motion during the processing.

[0097] (4) Pressing and sintering

[0098] The activated powder was molded under a hydraulic press at a pressure of 80 MPa for 10 minutes; then it was further pressed by isostatic pressing at a pressure of 280 MPa for 20 minutes to obtain the desired sintered green body with a relative density of 65.2%.

[0099] After drying the sintered blank, it is subjected to degreasing and sintering treatment. Specifically, the target blank is first heated to 400℃ at a heating rate of 0.5℃ / min and held at that temperature for 5 hours; then heated to 700℃ at a heating rate of 0.6℃ / min and held at that temperature for 50 hours.

[0100] After degreasing, the temperature was increased from 700℃ to a first sintering temperature of 1290℃ at a first heating rate of 0.5℃ / min, and held for 20 hours in an air environment with an oxygen content of 20-30%. Then, the temperature was increased to a second sintering temperature of 1450℃ at a second heating rate of 5℃ / min, and held for 5 hours in an air environment with an oxygen content of 30-40%. Finally, the temperature was decreased to the first sintering temperature of 1290℃ at a first cooling rate of 3℃ / min, and held for 40 hours in an air environment with an oxygen content of 30-40%. The material was then cooled to room temperature at a second cooling rate of 1℃ / min in an air environment with an oxygen content of 20-30%, yielding the sintered target material.

[0101] After machining the obtained target sintered body, it is bonded to a metal backing plate using an indium bonding method to obtain the desired target material.

[0102] The target material prepared in Example 1 was tested. The relative density of the target material was measured to be 99.5% using a density scale, and the resistivity of the target material was measured to be 8.4 mΩ·cm using a four-probe instrument. Electron microscopy was performed on the cross-section of the target material, and the results are as follows... Figure 1 As shown in the figure. It can be seen that the target material prepared in this embodiment has very high density and no obvious pores; furthermore, as... Figure 2As shown, by preparing the polished sample, the average grain size of the target material was measured to be approximately 3.2 μm, of which the 2–6 μm grains accounted for approximately 91.2%.

[0103] Examples 2-8

[0104] Examples 2-8 all provide a method for preparing an oxide sintered body, specifically referring to Example 1, with the only difference being the composition of the raw materials, which are weighed according to the molar ratio of each metal atom in Table 1.

[0105] Table 1. Atomic ratios of various elements in different sintered bodies from Examples 1-8.

[0106] sintered body Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 In at.% 49.5 49.5 49.5 49.5 49.5 49.5 56.5 42.6 Ga at.% 24.75 24.75 24.75 24.75 24.75 24.75 14 14.3 Zn at.% 24.75 24.75 24.75 24.75 24.75 24.75 28 42.6 Pr at.% 1.00 / / / / / 1.50 / Ce at.% / 1.00 / / / / / / Sm at.% / / 1.00 / / / / / Eu at.% / / / 1.00 / / / Tb at.% / / / / 1.00 / / 0.50 Tm at.% / / / / / 1.00 / /

[0107] For example: Example 2 replaces praseodymium oxide in Example 1 with an equimolar amount of cerium oxide; Example 3 replaces praseodymium oxide in Example 1 with an equimolar amount of samarium oxide; Example 4 replaces praseodymium oxide in Example 1 with an equimolar amount of europium oxide; Example 5 replaces praseodymium oxide in Example 1 with an equimolar amount of terbium oxide; Example 6 replaces praseodymium oxide in Example 1 with an equimolar amount of thulium oxide. Examples 7 and 8 are based on Example 1, but with adjustments to the types of rare earth elements and the amounts of metal elements used.

[0108] The target material prepared in Example 2 was characterized. The relative density of the target material was measured to be 99.1% using a density scale, and the resistivity of the target material was measured to be 22.3 mΩ·cm using a four-probe instrument. Electron microscopy was performed on the cross-section of the target material, and the results are as follows... Figure 3 As shown in the figure. It can be seen that the target material prepared in this embodiment has very high density and no obvious pores; furthermore, as... Figure 4 As shown, by preparing the polished sample, the average grain size of the target material was measured to be approximately 4.5 μm, of which the 2–6 μm grains accounted for approximately 85.4%.

[0109] The target material prepared in Example 5 was characterized. The relative density of the target material was measured to be 99.6% using a density scale, and the resistivity of the target material was measured to be 12.5 mΩ·cm using a four-probe instrument. Electron microscopy was performed on the cross-section of the target material, and the results are as follows: Figure 5 As shown in the figure. It can be seen that the target material prepared in this embodiment has very high density and no obvious pores; furthermore, as... Figure 6 As shown, by preparing the polished sample, the average grain size of the target material was measured to be approximately 3.1 μm, of which the 2–6 μm grains accounted for approximately 84.4%.

[0110] Example 9

[0111] The only difference from Example 1 is that the rare earth oxide is praseodymium oxide, with a praseodymium content of 0.5 at%; the second metal compound is gallium oxide, zinc oxide, and praseodymium fluoride, wherein the contents of gallium oxide and zinc oxide are the same as in Example 1, while the praseodymium content in praseodymium fluoride is 0.5 at%. The other processes in this example are the same as in Example 1.

[0112] The target material prepared in Example 9 was characterized. The relative density of the target material was measured to be 99.3% using a density scale, and the resistivity was measured to be 13.5 mΩ·cm using a four-probe instrument. Electron microscopy analysis of the cross-section of the target material showed that the target material prepared in this example has very high density and no obvious porosity. Furthermore, by preparing a polished sample, the average grain size of the target material was measured to be approximately 3.5 μm, with grains of 2–6 μm accounting for approximately 91.5%.

[0113] Examples 10-13

[0114] The only difference from Example 1 is that the types and content ratios of the first and second metal compounds remain the same, while the content of rare earth praseodymium oxide is adjusted to a certain extent, as follows: the content of elemental praseodymium is set to 0.1 at% (Example 10), 0.3 at% (Example 11), 8.0 at% (Example 12), and 12.0 at% (Example 13). The other processes in this example are the same as those in Example 1.

[0115] Testing of the fabricated targets showed that when the praseodymium content was 0.1 at%, the characteristics of the target, thin film, and devices were not significantly different from those without doping, indicating that it did not improve the properties. When the praseodymium content was 0.3 at%, the target properties were superior, with a relative density of 99.1% and a resistivity of 4.5 mΩ·cm. The target exhibited high density and no significant porosity. Furthermore, the devices fabricated using this target showed excellent photoelectric properties, demonstrating great application potential in thin-film transistors and detectors. When the praseodymium content was 8.0 at%, the target properties were still relatively good, but the photoelectric properties of the thin film were somewhat affected, particularly the Hall mobility, which decreased by 30%, impacting its applications. Finally, when the praseodymium content was 12.0 at%, ... Figure 7 As shown, the target material contains a large number of pores, making it impossible to obtain a high-density target material and thus unsuitable for mass production. Therefore, the results indicate that targets with a rare earth content of 0.1–8 at% exhibit superior overall properties.

[0116] Example 14

[0117] The only difference from Example 1 is that the particle size of each raw material is different, as follows: In order to further study the influence of the original particle size of the powder, we set up raw material powders with different particle sizes for comparative study.

[0118] In Experiment ①, powders of indium oxide, gallium oxide, zinc oxide, and rare earth oxides were weighed according to the molar ratios of each metal atom in Example 1 of Table 1, with a total weight of 3 kg. The average particle size of the indium oxide powder was 0.5 μm, the zinc oxide powder was 0.9 μm, the gallium oxide powder was 2.1 μm, and the praseodymium oxide powder was 0.5 μm. Testing of the fabricated target material showed that the relative density was 98.5%, the average grain size was 10.5 μm, and the proportion of 2–6 μm grains was approximately 30.5%. Figure 8 As shown, due to the grain distribution problem of the target material, its bending strength is poor, and the target material will crack severely during the sputtering process.

[0119] In Experiment ②, powders of indium oxide, gallium oxide, zinc oxide, and rare earth oxides were weighed according to the molar ratios of each metal atom in Example 1 (Table 1), with a total weight of 3 kg. The average particle size of the indium oxide powder was 2.8 μm, the zinc oxide powder was 0.9 μm, the gallium oxide powder was 2.1 μm, and the praseodymium oxide powder was 2.3 μm. Testing of the fabricated target material showed a relative density of 97.5% and an average grain size of 8.5 μm, with grains of 2–6 μm accounting for approximately 50.3%. Figure 9 As shown, due to the grain distribution problem of the target material, its bending strength is poor, and the target material also suffers from severe cracking during the sputtering process.

[0120] Therefore, based on the results of each embodiment, we believe that under the conditions of the present invention, better material properties can be obtained when the particle size of the raw material powder satisfies the following condition: particle size of indium oxide > particle size of the second metal compound > particle size of rare earth oxide.

[0121] Example 15

[0122] The only difference from Example 1 is the sintering process; everything else remains the same. The specific sintering process in this example is as follows: After degreasing, the temperature is increased from 700°C to a first sintering temperature of 1150°C at a first heating rate of 0.5°C / min, and held for 20 hours in an air environment with an oxygen content of 20-30%. Then, the temperature is increased to 1350°C at a heating rate of 1°C / min, and held for 30 hours in an air environment with an oxygen content of 20-30%. Next, the temperature is increased from 1350°C to a second sintering temperature of 1460°C at a heating rate of 4°C / min, and held for 3 hours in an air environment with an oxygen content of 30-40%. Then, the temperature is decreased to 1200°C at a cooling rate of 3°C / min, and held for 50 hours in an air environment with an oxygen content of 30-40%. Finally, the temperature is decreased to room temperature at a cooling rate of 1°C / min in an air environment with an oxygen content of 20-30%, yielding the sintered target material.

[0123] As can be seen from the above, in this embodiment, the holding time of the first sintering temperature range is (20+30+50), which is 100 hours, and the holding time of the second sintering temperature range is 3 hours. Therefore, the proportion of the first sintering temperature range is approximately 97.1%.

[0124] The target material prepared in this embodiment was characterized. The relative density of the target material was measured to be 99.6% using a density scale, and the resistivity was measured to be 6.5 mΩ·cm using a four-probe instrument. Electron microscopy analysis of the cross-section of the target material showed that the target material prepared in this embodiment has very high density and no obvious porosity. Furthermore, by preparing a polished sample, the average grain size of the target material was measured to be approximately 3.0 μm, with grains of 2–6 μm accounting for approximately 95.3%.

[0125] In addition, a comparative experiment was also conducted with reference to Example 15, mainly adjusting the holding time at the second sintering temperature, while keeping other parameters the same. Figure 10 As shown, when sintering at a second sintering temperature is not performed, the density of the sintered body is low, and a dense ceramic material is not formed, which cannot meet the requirements for mass production. Figure 11 As shown, when the holding time at the second sintering temperature is 30 hours, which means the proportion of the first sintering temperature range is approximately 76.9%, the resulting sintered body has low density and contains many pores, failing to meet mass production requirements.

[0126] Example 16

[0127] The only difference from Example 1 is that no activation is performed.

[0128] To investigate the effect of powder activation process on the preparation method of sintered body of the present invention, this embodiment uses unactivated powder, while other aspects remain the same as in Example 1.

[0129] Scanning electron microscopy tests of the fabricated target material, such as Figure 12 As shown, the target material has a lot of pores, which cannot meet the requirements of mass production. The results show that activation treatment of the granulated powder can significantly improve the density of the target material and improve its quality.

[0130] Comparative Example 1

[0131] The only difference from Example 1 is that praseodymium oxide is replaced with indium oxide in an equimolar ratio, that is, rare earth elements are not introduced.

[0132] The target material prepared in Comparative Example 1 was characterized by testing. The relative density of the target material was measured to be 99.4% using a density scale, and the resistivity was measured to be 7.5 mΩ·cm using a four-probe instrument. Electron microscopy analysis of the cross-section of the target material showed that the target material prepared in this example has very high density and no obvious porosity. Furthermore, by preparing a polished sample, the average grain size of the target material was measured to be approximately 5.5 μm, with grains of 2–6 μm accounting for approximately 90.3%.

[0133] In summary, compared with the target material in Example 1, the relative density and resistivity of the two are comparable, and the introduction of rare earth oxides can reduce the average grain size to some extent. This may be because rare earth praseodymium can exist as a liquid-phase solid solution support during high-temperature sintering, reducing the phase transition energy and thus facilitating the smooth progress of the sintering process.

[0134] It should be noted that thin-film transistor devices made using this target material have poor photoelectric properties and cannot meet the requirements of relevant application scenarios.

[0135] Comparative Example 2

[0136] Experiment ①: The only difference from Example 1 is the proportion of high-valence ions of praseodymium in the rare earth oxides, which differs from Example 1. 4+ / (Pr 3+ +Pr 4+ The values ​​of ) are different, as shown in Table 2, and the photoelectric properties of the thin film transistor device made from the target material were evaluated.

[0137] Table 2. Evaluation results of the photoelectric properties of thin-film transistor devices

[0138]

[0139] For example, Figure 13 Figure (a) shows the X-ray photoelectron spectroscopy (XPS) analysis of the target material prepared in Example 1. Gaussian peak fitting revealed that the proportion of high-valence ions in the rare earth element praseodymium was approximately 25.3%, i.e., Pr 4+ / (Pr3+ +Pr 4+ =25.3%.

[0140] In summary, for rare earth praseodymium, Pr 4+ / (Pr 3+ +Pr 4+ When the percentage value of ) is 20% to 40%, it has relatively superior characteristics.

[0141] Experiment ②: The only difference from Example 5 is the proportion of high-valence ions of terbium in the rare earth oxides, i.e., Tb 4+ / (Tb 3+ +Tb 4+ The values ​​of ) are different, as shown in Table 3, and the photoelectric properties of the thin film transistor device made from the target material were evaluated.

[0142] Table 3. Evaluation results of the photoelectric properties of thin-film transistor devices

[0143]

[0144]

[0145] For example, Figure 13 Figure (b) shows the X-ray photoelectron spectroscopy (XPS) analysis of the target material prepared in Example 5. Gaussian peak fitting revealed that the proportion of high-valence ions in the rare earth element terbium was approximately 48.5%, i.e., Tb 4+ / (Tb 3+ +Tb 4+ = 48.5%.

[0146] In summary, for rare earth terbium, Tb 4+ / (Tb 3+ +Tb 4+ When the percentage value of ) is 40% to 60%, it has relatively superior characteristics.

[0147] Experimental Example 1

[0148] The parameters of the sintered bodies prepared in the test examples and comparative examples, including relative density, resistivity, rare earth element valence state, grain size, and other related tests, are shown in Table 4 below.

[0149] Table 4 Test results of sintered bodies from each embodiment

[0150]

[0151] Based on the characteristics of the sintered bodies prepared in Examples 1 to 8, the relative density can reach over 99%, and the resistivity is relatively low. Among them, the cerium oxide sintered body has a relatively high resistivity (22.3 mΩ·cm). The average grain size of each sintered body is small, all less than 5 μm, and the proportion of grains with a size of 2 to 6 μm is maintained at over 80%, which ensures the mechanical strength and other properties of the target material.

[0152] It can be seen that the sintered body or target material prepared in the embodiments of the present invention has controllable grain size and high density.

[0153] Experimental Example 2

[0154] Thin films and thin-film transistor devices were prepared using the targets obtained in the examples and comparative examples, and their performance was tested. The results are as follows:

[0155] Table 4 shows the Hall mobility and carrier concentration values ​​of the thin films fabricated using each target material in Examples 1-8. The specific fabrication conditions were as follows: target size was 6 inches in diameter and 6 mm in thickness; magnetron sputtering equipment was used, and the base vacuum was 2.1 × 10⁻⁶. -5 Pa, the substrate was not heated, the oxygen content in the sputtering atmosphere was 20%, the DC power supply sputtering power was 300W, and the thin films were all 100nm in size. Then the Hall properties of the thin films were characterized.

[0156] Table 4. Hall mobility and carrier concentration values ​​for thin films fabricated using various targets.

[0157]

[0158] In addition, to further evaluate the properties of the prepared target material, a series of thin-film transistor devices were fabricated, employing a self-aligned structure, the schematic diagram of which is shown below. Figure 14 As shown, the following are provided: a substrate 01, a buffer layer 08, an active layer 04, a gate insulating layer 03 located on the active layer 04 and a gate 02, a spacer layer 09 covering the upper surfaces of the active layer 04 and the gate 02, and a source electrode 06 and a drain electrode 07 located on the spacer layer 09 and electrically connected to both ends of the active layer 04.

[0159] The materials of each part are as follows: Substrate 01 is a hard glass substrate; buffer layer 08 is silicon oxide prepared by plasma-enhanced chemical vapor deposition; active layer 04 is a thin film made of the target material in each embodiment; gate insulating layer 03 is silicon oxide with a thickness of 300 nm; gate 02 is a copper / molybdenum (Cu / Mo) stacked structure prepared by magnetron sputtering with a thickness of 200 / 20 nm. Spacer layer 09 is a silicon oxide / silicon nitride stacked structure with a thickness of 500 / 100 nm; source 06 and drain 07 are copper / molybdenum (Cu / Mo) stacked structures prepared by magnetron sputtering with a thickness of 200 / 20 nm.

[0160] For example, thin-film transistor devices fabricated using targets without rare earth elements and those with rare earth elements as described in Comparative Example 1, wherein... Figure 15 (a) shows a device without rare earth elements. Figure 15 (b) shows a device doped with rare earth elements. The negative bias photothermal stability of the device was evaluated as follows: the substrate temperature was 70°C, and a commercial white LED light source was used to illuminate the active layer O4 of the thin-film transistor device at a light intensity of 8000 nits. Simultaneously, a -30V voltage was applied to the gate of the device, and a 0V bias voltage was applied across the source and drain electrodes. The negative bias thermal stability characteristics of the device under light irradiation were obtained by testing the transfer characteristic curves of the device after a certain period of time. A large change in device characteristics indicates poor stability, and vice versa.

[0161] like Figure 15 As shown, after incorporating a certain amount of rare earth oxides, the negative bias stability of the device is significantly improved from -7.8V to -0.2V; this indicates that the incorporation of rare earth oxides can significantly improve the optoelectronic properties of the device and expand its application areas.

[0162] As can be seen, the target material prepared using this embodiment is used to prepare thin films through magnetron sputtering for the channel layer of thin film transistors. The resulting devices have excellent electrical characteristics and good stability, especially in terms of light-related stability, which is significantly improved compared to other related products. This greatly expands the application scenarios and fields of thin film transistors.

[0163] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An oxide sintered body, characterized in that, It includes a first metal compound, a rare earth oxide, and a second metal compound; the first metal compound is indium oxide, and the second metal compound is selected from at least one of metal oxides and metal fluorides; In the oxide sintered body, the molar percentages of indium, rare earth elements, and other metal elements in the total metal elements of the sintered body are (10%~98%), (0.1%~8%), and (1%~88%), respectively. The method for preparing the oxide sintered body includes: preparing the oxide sintered body using indium oxide, rare earth oxides, and a second metal compound as raw materials; pre-treating the raw materials to obtain a mixed powder with a particle size that meets the requirements; granulating the mixed powder to obtain a granulated powder; pressing the granulated powder into a sintered body blank; and sintering the sintered body blank. In the raw materials, the particle sizes of indium oxide, rare earth oxide, and the second metal compound satisfy the following condition: particle size of indium oxide > particle size of the second metal compound > particle size of rare earth oxide; the mixed powder satisfies D50 = 0.10 μm ~ 1.15 μm, and D10 ≥ 0.05 μm, D90 ≤ 2.0 μm, and the particle size distribution coefficient of the mixed powder is P = (D90... D10) / D50, P≤2.0; The granulated powder is sieved to obtain particles with a diameter of 25μm to 50μm; the sieved powder is first activated and then pressed into a sintered green body. The activation method is to irradiate with ultraviolet light with a wavelength of 100nm to 400nm. The rare earth oxide is selected from at least one of praseodymium oxide and terbium oxide; the rare earth element in the oxide sintered body has two valence states, with Pr in the rare earth praseodymium oxide having two valence states. 4+ / (Pr 3+ +Pr 4+ The percentage of Tb in rare earth terbium is 20%~40%. 4+ / (Tb 3+ +Tb 4+ The percentage value is 40%~60%.

2. The oxide sintered body according to claim 1, characterized in that, The metal oxide is selected from at least one of zinc oxide, tin oxide, gallium oxide, tantalum oxide, titanium oxide, aluminum oxide, antimony oxide, bismuth oxide, and hafnium oxide.

3. The oxide sintered body according to claim 1, characterized in that, The metal fluoride is selected from at least one of tin fluoride, zinc fluoride, gallium fluoride, vanadium fluoride, praseodymium fluoride, and terbium fluoride.

4. The oxide sintered body according to claim 1, characterized in that, The resistivity of the oxide sintered body is 0.01~30 mΩ•cm, and the relative density is greater than 98.0%.

5. The oxide sintered body according to claim 4, characterized in that, The resistivity of the oxide sintered body is 0.1~10 mΩ•cm, and the relative density is greater than 99.0%.

6. The oxide sintered body according to claim 1, characterized in that, The grain size in the oxide sintered body is less than 10 μm, and the proportion of grains with a grain size of 2 μm to 6 μm is greater than 80%.

7. The oxide sintered body according to claim 1, characterized in that, The oxide sintered body contains at least two crystalline phases.

8. A method for preparing an oxide sintered body according to any one of claims 1-7, characterized in that, include: The raw materials are pretreated to obtain a mixed powder with a particle size that meets the requirements. The mixed powder is then granulated to obtain a granulated powder. The granulated powder is pressed into a sintered green body and then sintered. In the raw materials, the particle sizes of indium oxide, rare earth oxide, and the second metal compound satisfy the following condition: particle size of indium oxide > particle size of the second metal compound > particle size of rare earth oxide; the mixed powder satisfies D50 = 0.10 μm ~ 1.15 μm, and D10 ≥ 0.05 μm, D90 ≤ 2.0 μm, and the particle size distribution coefficient of the mixed powder is P = (D90... D10) / D50, P≤2.0; The granulated powder is sieved to obtain particles with a diameter of 25μm to 50μm; the sieved powder is first activated and then pressed into a sintered green body. The activation method is to irradiate with ultraviolet light with a wavelength of 100nm to 400nm. The rare earth oxide is selected from at least one of praseodymium oxide and terbium oxide; the rare earth element in the oxide sintered body has two valence states, with Pr in the rare earth praseodymium oxide having two valence states. 4+ / (Pr 3+ +Pr 4+ The percentage of Tb in rare earth terbium is 20%~40%. 4+ / (Tb 3+ +Tb 4+ The percentage value is 40%~60%.

9. The preparation method according to claim 8, characterized in that, The sintered body blank is first dried and degreased before being sintered.

10. The preparation method according to claim 9, characterized in that, The sintering process includes sintering at a first sintering temperature and a second sintering temperature, respectively. The first sintering temperature is 1000℃~1400℃, and the holding time is t1. The second sintering temperature is 1450℃~1600℃, and the holding time is t2. The percentage value of t1 / (t1+t2) is 85%~98%.

11. The preparation method according to claim 8, characterized in that, The pretreatment process includes wet ball milling and wet grinding performed sequentially.

12. The preparation method according to claim 11, characterized in that, The wet-milled slurry is subjected to vacuum defoaming treatment before granulation.

13. The preparation method according to claim 12, characterized in that, Granulation is carried out by spray granulation, and the average particle size of the granulated powder is controlled to be 20μm~65μm.

14. An oxide target material, characterized in that, It is prepared by the oxide sintered body according to any one of claims 1-7 or the oxide sintered body prepared by the preparation method according to any one of claims 8-13.

15. The oxide target material according to claim 14, characterized in that, The oxide target material is either a planar target material or a rotating target material.

16. An oxide semiconductor thin film, characterized in that, It is prepared using the oxide target material as described in claim 14 or 15.

17. A thin-film device, characterized in that, Includes the oxide semiconductor thin film as described in claim 16.

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