Preparation method of cerium, tantalum and zinc co-doped tin oxide target material

Abstract

The invention relates to the technical field of tin oxide target materials, in particular to a preparation method of a cerium, tantalum and zinc co-doped tin oxide target material. The preparation method of the cerium-tantalum-zinc co-doped tin oxide target material comprises the following steps: firstly, dispersing and grinding oxide powder, a dispersing agent, an adhesive and a plasticizer for multiple times, then carrying out spray drying to obtain doped powder, then carrying out compression molding on the doped powder, and finally sintering according to a certain sintering curve to obtain the cerium-tantalum-zinc co-doped tin oxide target material. And processing and binding are carried out. The tin oxide powder is obtained by preparing gel through a sol-gel method and then performing frontage carbon dioxide extraction drying and high-temperature calcination, the specific surface area is high, agglomeration is not prone to occurring, the dispersity of doped oxide is good, and therefore the formed target material has the advantages of being high in compactness, high in relative density, low in electrical resistivity and good in stability. A thin film sputtered by the target material is relatively good in conductivity and relatively high in mobility.

Description

Technical Field

[0001] The present application relates to the technical field of tin oxide target materials, and in particular to a method for preparing a cerium-tantalum-zinc co-doped tin oxide target material. Background Art

[0002] With the rapid development of semiconductor technology, optoelectronic technology and new energy technology, the demand for high-performance thin film materials is growing. As an important wide bandgap semiconductor material, tin oxide has shown broad application prospects in transparent conductive films, gas sensors, solar cells and other fields due to its excellent chemical stability, thermal stability, good conductivity and light transmittance.

[0003] Tin oxide targets are formed by doping other elements into the tin oxide matrix after sintering. The thin films prepared by the tin oxide target using the magnetron sputtering process have excellent electrical conductivity and optical properties. However, most studies on the doping of tin oxide focus on single element or double element doping, and there are relatively few studies on the co-doping of three elements. In addition, existing doping methods often have problems such as uneven distribution of doping elements, poor density of target materials, and unstable performance, which make it difficult to meet the high requirements for material performance in the field of high-end technology.

[0004] The patent application document with publication number CN113563063A discloses a high-density fine-grained zinc oxide-doped tin oxide-based ceramic target and a preparation method thereof, comprising: (1) mixing tin oxide powder and zinc oxide powder in a mass ratio of 60-65:35-40, adding ammonium polyacrylate as a dispersant, and adding water to form a raw material mixture; (2) ball milling the raw material mixture on a ball mill; (3) sand milling the mixed slurry after ball milling on a sand mill; (4) adding a binder to the sand milled mixed slurry and stirring it evenly; (5) spray drying the stirred mixed slurry to obtain spherical mixed granulation powder; (6) molding the mixed granulation powder to obtain an original target blank; (7) cold isostatic pressing the original target blank to obtain a high-strength, high-density uniform target blank; (8) degreasing and sintering the uniform target blank to obtain a high-density fine-grained zinc oxide-doped tin oxide-based ceramic target. In this scheme, zinc oxide is doped in a tin oxide matrix, the grain size is small, and the relative density of the tin oxide-based ceramic target is not less than 98.5%. However, the conductivity of the target may be poor, and the sintering temperature is high, which increases the energy consumption. Summary of the invention

[0005] In order to improve the compactness of tin oxide target and reduce the resistivity, the present application provides a method for preparing tin oxide target co-doped with cerium, tantalum and zinc.

[0006] A method for preparing a cerium-tantalum-zinc co-doped tin oxide target comprises the following steps: S1: mixing cerium oxide powder, tantalum oxide powder, zinc oxide powder and water, adding a dispersant to disperse and grind to obtain slurry A; S2: mixing tin oxide powder with water, adding a dispersant for dispersion, adding slurry A, a binder and a plasticizer, grinding, and obtaining slurry B; S3: spray drying and sieving slurry B to obtain doped powder; S4: pressing and cold isostatically pressing the doped powder to obtain a green blank; S5: sintering the green blank in an air atmosphere to obtain a target material; S6: Process and bind the target material; The tin oxide powder is prepared by a method comprising the following steps: (1) An aqueous solution of tin chloride pentahydrate is mixed with ethanol, polyvinyl pyrrolidone is added, the pH is adjusted to 9-10, the mixture is reacted at room temperature for 2-5 hours, aged for 6-12 hours, and centrifuged and washed to obtain a tin oxide precursor gel; (2) The tin oxide precursor gel is extracted and dried by supercritical carbon dioxide, and then treated at 500-650° C. for 2-4 hours to obtain the tin oxide precursor gel.

[0007] In the above technical scheme, firstly, in the process of preparing the slurry, multiple dispersions and multiple grindings are adopted to prevent the agglomeration of powder particles, improve the uniformity of dispersion of the various components of the slurry, refine the particles, and increase the specific surface area and reaction activity of the particles, thereby laying the foundation for the preparation of high-density and high-uniformity target materials. Moreover, the addition of binders and plasticizers further increases the density of the slurry and reduces the defects inside the target material; secondly, the ground slurry is spray-dried and sieved to obtain a doped powder with good fluidity, and after pressing and molding, a target blank with high density, good density and high uniformity is obtained; finally, the blank is sintered according to a specific sintering curve to obtain a target material with high density, good density and low resistivity, which can be processed and bound.

[0008] In the above preparation process, on the one hand, since cerium and tantalum can provide more ions and thus provide more oxygen vacancies, they can introduce additional carriers and adjust the electronic band structure, which can improve the mobility of the co-doped tin oxide target sputtered film, thereby improving the conductivity of the film; therefore, by co-doping tin oxide with cerium oxide, tantalum oxide and zinc oxide, a tin oxide target with excellent performance can be obtained, and the sputtered film has good uniformity and good conductivity. In addition, the indium-free target has high density and low resistivity, and the sputtered film has high transmittance in both the visible light and near-infrared light regions, and has good conductivity.

[0009] Secondly, the tin oxide powder is prepared by a sol-gel method, and polyvinyl pyrrolidone is added during the preparation process as a template. After centrifugal washing, the polyvinyl pyrrolidone is removed, which further improves the specific surface area and surface roughness of the nano-tin oxide, and has more active sites. When doped with cerium oxide, tantalum oxide and zinc oxide, the doped ions are more easily and evenly distributed on the surface of the nano-tin oxide particles, which improves the uniformity of the doping of cerium oxide, tantalum oxide and zinc oxide, and is conducive to the formation of a more uniform crystal structure and conductive channel, thereby improving the density and uniformity of the target material and reducing the resistivity; at the same time, the nano-tin oxide prepared by the above method has a large specific surface area, which can also promote the transmission of substances during the sintering process, and is conducive to the formation of a denser target structure.

[0010] Preferably, in steps S1 and S2, the dispersant is one or more of sodium dodecyl sulfate, sodium oleate and ammonium polyacrylate; the binder is polyvinyl acetate or polyvinyl alcohol; the plasticizer is polyethylene glycol or 2-nitrophenyl octyl ether; the mass ratio of the cerium oxide powder, tantalum oxide powder, zinc oxide powder and tin oxide powder is (0.2-0.8): (0.5-2): (0.2-0.6): (96.6-99.1); the mass ratio of the sum of the mass of the cerium oxide powder, tantalum oxide powder, zinc oxide powder and tin oxide powder, the total amount of pure water, the total amount of dispersant, the binder and the plasticizer is 100: (45-160): (1-4): (5-24): (0.2-1.2).

[0011] In the above technical solution, the dispersant is an amphiphilic surfactant that can evenly disperse cerium oxide, tantalum oxide, zinc oxide and tin oxide powders in pure water to prevent the powder particles from agglomerating due to high surface energy, thereby forming a stable and uniform slurry; the addition of a plasticizer can reduce the viscosity of the slurry, making it easier to flow and mix, forming a uniform slurry; the addition of a binder can enhance the bonding force between cerium oxide, tantalum oxide, zinc oxide and tin oxide particles, improve the uniformity of the slurry, and also improve the density and stability of the slurry. Therefore, the addition of a dispersant, a plasticizer and a binder is conducive to the formation of a uniform and stable slurry, laying the foundation for the preparation of high-density and high-density target materials.

[0012] Preferably, in step S1, the mass ratio of the sum of the masses of cerium oxide, tantalum oxide, zinc oxide, pure water, and dispersant is (9-34): (30-70): (3-12.5); the dispersion time is 10-60 min, the grinding speed is 1000-1800 rpm, the grinding time is 60-300 min, and the particle size after grinding D90 is ≤0.8 μm.

[0013] In the above technical scheme, if the dispersion time is short or the grinding is insufficient, the dispersibility of the slurry will deteriorate, and a large number of agglomerates will still be contained in the green blank. During the sintering process, these agglomerates will be pre-sintered first, resulting in asynchronous sintering between the agglomerates and the matrix. A large number of pores will be formed between the high-density agglomerates and the matrix. These pores are difficult to be discharged through sintering, thereby reducing the density of the target material.

[0014] Preferably, in step S2, the dispersion time is 30-120 min, the grinding speed is 1000-1800 rpm, the grinding time is 100-300 min, and the particle size after grinding is D90≤0.6 μm.

[0015] Preferably, in step S3, the inlet air temperature of the spray drying is 160-250°C, the outlet air temperature is 50-130°C, the spray speed is 7000-15000rpm; and the mesh size of the sieving is 40-120 mesh.

[0016] Preferably, in step S4, the pressing is first performed by using a hydraulic press for pre-pressing, and then by using a cold press for pressing, the cold pressing pressure is 200-400 MPa, and the cold pressing time is 1-100 min.

[0017] Preferably, in step S5, the sintering is divided into a degreasing stage, a heating stage, and a cooling stage. In the degreasing stage, the temperature is raised from room temperature to 600°C at a rate of 0.1-0.6°C / min, and kept warm for 5-10h; in the heating stage, the temperature is first raised from 600°C to 1300-1400°C at a rate of 0.1-1°C / min, and kept warm for 3-15h, and then cooled to 1250-1350°C at a rate of -1 to -3°C / min, and kept warm for 0.5-1h; in the cooling stage, the temperature is cooled from 1250-1350°C to room temperature at a rate of -3°C to -5°C / min.

[0018] In the above technical scheme, on the one hand, in order to improve the uniformity, stability and other properties of the slurry, additives such as dispersants, plasticizers, binders, etc. are added during the slurry preparation process. These additives will not only reduce the purity of the target material, but also affect the densification process of the target material during the sintering process. If they are not removed cleanly, the sintered target material will have irreversible defects such as pores, cracks, and deformation. Therefore, it is very necessary to degrease the blank first, and the degreasing rate cannot be too fast, otherwise the additives cannot be removed smoothly and continuously, affecting the quality of the target material.

[0019] Secondly, the sintering of the target material is mainly divided into three stages: the initial stage of sintering: the particles begin to contact and connect to form a sintering neck, and the large pores are pinned on the grain boundaries, hindering the growth of grains. The density does not increase significantly at this stage, and the grain size is small; the middle stage of sintering: the sintering neck continues to expand, and the continuous open pores formed between the particles gradually shrink into closed pores. The shape of the pores tends to be spherical. The volume diffusion and grain boundary diffusion mechanisms shrink the sintered body, and the pores shrink. The density is greatly improved at this stage, and the grains grow; the late stage of sintering: the spherical pores continue to shrink or disappear, and most of the pores can be discharged from the body through the material migration mechanism, but there are still a small number of closed pores remaining in the grains that are difficult to eliminate. The reduction in the number of pores weakens the pinning effect on the grain boundaries, and the grain boundaries move "freely". The speed of grain boundary migration will be faster than the speed of pore movement, resulting in the decoupling of grain boundaries and pores, and abnormal grain growth. In the above-mentioned heating process, the temperature is first raised to 1300-1400°C at a certain rate and kept at a certain time. At this time, as the grains grow, the pores shrink and the speed of grain boundary migration accelerates. If the temperature is lowered at a faster rate and kept at a certain time, the grown grains do not have enough energy to migrate at the grain boundaries. At this time, the migration of the grain boundaries is suppressed, which hinders the abnormal growth of the grains. Therefore, the sintered grains will not have an adverse effect on the performance of the target material due to their excessive size.

[0020] Preferably, in step S6, the target material is processed to a surface roughness of 0.4-1.0, the binding material is metal indium, and the binding rate is ≥85%.

[0021] Preferably, in step (1), the mass ratio of tin chloride pentahydrate to polyvinyl pyrrolidone is 100:(35-95).

[0022] In the above technical scheme, if the amount of polyvinyl pyrrolidone added is small, the nano-tin oxide formed has fewer pores, smaller specific surface area, and fewer active sites, which affects the dispersibility of cerium oxide, tantalum oxide and zinc oxide; if the amount of polyvinyl pyrrolidone added is too much, the nano-tin oxide formed has more pores and larger pores, and the pores may collapse, which not only affects the specific surface area of ​​the nano-tin oxide, but also may make the nano-tin oxide particles uneven.

[0023] Preferably, in step (2), the conditions for supercritical carbon dioxide extraction and drying are: the flow rate of supercritical carbon dioxide is 15-50 mL / min, the temperature of extraction and drying is 38-50° C., the pressure is 10-15 MPa, the time of extraction and drying is 3-7 h, and after drying, the pressure is quickly released to normal pressure, and then purged with dry air to reduce the temperature to room temperature.

[0024] By adopting the above technical scheme, when the specific surface area of ​​nano-tin oxide is large, agglomeration is likely to occur. In order to reduce the generation of agglomeration, the tin oxide precursor gel is dried by supercritical carbon dioxide extraction and drying. Supercritical carbon dioxide and ethanol are replaced in an autoclave, and ethanol in the gel is continuously replaced by carbon dioxide and continuously taken out by carbon dioxide fluid. After rapid pressure relief, the pressure drops to normal pressure instantly, and the liquid supercritical carbon dioxide in the gel is instantly gasified, the volume of the gel expands rapidly, the gaps between the nanoparticles increase, and the particles maintain a loose aggregation state. When heat treatment is performed, it is beneficial to reduce the aggregation and fusion of the nanoparticles, thereby reducing the agglomeration of the nanoparticles, and is beneficial to improving the uniformity and density of the target material, thereby improving the mobility of the sputtered film and reducing the resistivity.

[0025] The above technical solution of the present application includes at least the following beneficial effects: 1. This application uses polyvinyl pyrrolidone as a template and adopts a sol-gel method to prepare nano-tin oxide with a large specific surface area and high activity, improves the dispersibility of cerium oxide, tantalum oxide and zinc oxide, so as to make the doping more uniform, and performs drying treatment by supercritical carbon dioxide extraction and drying to reduce the agglomeration between nanoparticles, thereby further improving the density and conductivity of the target material; 2. This application adopts a unique sintering curve for sintering, which can reduce the generation of abnormal grains, improve the uniformity of grains, reduce crystal defects, thereby improving the density of the target material and reducing internal defects of the target material; and the sintering temperature is low, reducing energy consumption; 3. The present application uses cerium oxide, tantalum oxide and zinc oxide to co-dope tin oxide, which can improve the density and conductivity of the target material, thereby improving the mobility and conductivity of the film sputtered by the target material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the SEM image of the doped powder; Figure 2 is the SEM image of the target after sintering; Figure 3 This is the target image after processing. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the embodiments.

[0028] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0029] Example Example 1 The method for preparing the cerium-tantalum-zinc co-doped tin oxide target of this embodiment comprises the following steps: S1: Weigh 2g of cerium oxide powder, 5g of zinc oxide powder, 2g of tantalum oxide powder, 3g of sodium dodecyl sulfate and 30g of pure water and disperse them for 10min, grind them at 1000rpm for 60min using a grinder to obtain slurry A, and the particle size D90 after grinding is 0.8μm; S2: Weigh 991 g of tin oxide powder, 7 g of sodium dodecyl sulfate and 1570 g of pure water, disperse for 30 min, add slurry A, 50 g of polyvinyl alcohol and 2 g of 2-nitrophenyl octyl ether, and grind at 1000 rpm for 300 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.6 μm; S3: spray drying slurry B, with an inlet air temperature of 160°C, an outlet air temperature of 50°C, and a rotation speed of 7000 rpm. After spray drying, the slurry is sieved through a 40-mesh sieve to obtain a doped powder; S4: placing the doped powder in a mold, pre-pressing it with a hydraulic press, and then pressing it with a cold press, the cold pressing pressure is 200 MPa, and the cold pressing time is 100 min to obtain a green blank; S5: placing the green blank in a normal pressure furnace for sintering in air atmosphere. During sintering, firstly, the temperature is raised from room temperature to 600°C at a rate of 0.1°C / min, and kept at this temperature for 5 hours. Then, the temperature is raised from 600°C to 1300°C at a rate of 0.1°C / min, and kept at this temperature for 3 hours. Then, the temperature is lowered to 1250°C at a rate of -1°C / min, and kept at this temperature for 1 hour. Finally, the temperature is lowered from 1250°C to room temperature at a rate of -3°C / min, and a target material is obtained. S6: processing the target material, the roughness of the processed target material is 1.0, and the processed target material is bound with metal indium, and the target material binding rate is 85%; In this embodiment, the tin oxide powder is prepared by a method comprising the following steps: (1) Weigh 50 g of a 20% aqueous solution of tin chloride pentahydrate and dissolve it in 250 mL of ethanol. Add 3.5 g of polyvinyl pyrrolidone while stirring. Add ammonia water dropwise to adjust the pH value to 9. React at 25°C for 5 h. Aged for 6 h. Centrifuge the gel, remove the supernatant, wash with ethanol, centrifuge again, and wash with ethanol again. Repeat the centrifugation and washing until no chloride ions are detected in the supernatant to obtain a tin oxide precursor gel. (2) The tin oxide precursor gel is placed in a high-pressure extraction kettle for supercritical carbon dioxide extraction and drying. The supercritical carbon dioxide flow rate is set to 15 mL / min, the temperature of the high-pressure extraction kettle is set to 38°C, the pressure is set to 15 MPa, and the extraction and drying time is set to 3 h. After drying, the pressure is quickly released to normal pressure and purged with dry air. The temperature is lowered to room temperature. The cooled powder is placed in a muffle furnace and treated at 500°C for 4 h to obtain the powder.

[0030] Example 2 The method for preparing the cerium-tantalum-zinc co-doped tin oxide target of this embodiment comprises the following steps: S1: Weigh 2 g of cerium oxide powder, 5 g of zinc oxide powder, 2 g of tantalum oxide powder, 12.5 g of sodium oleate and 70 g of pure water and disperse them for 60 min. Use a grinder to grind at a speed of 1800 rpm for 300 min to obtain slurry A. The particle size D90 after grinding is 0.6 μm. S2: Weigh 991 g of tin oxide powder, 28.5 g of sodium oleate and 380 g of pure water, disperse for 120 min, add slurry A, 240 g of polyvinyl acetate and 12 g of polyethylene glycol 400, and grind at a speed of 1800 rpm for 100 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.5 μm; S3: spray drying slurry B, with an air inlet temperature of 250°C, an air outlet temperature of 130°C, and a rotation speed of 15000 rpm. After spray drying, the slurry is sieved through a 120-mesh sieve to obtain a doped powder; S4: placing the doped powder in a mold, pre-pressing it with a hydraulic press, and then pressing it with a cold press. The cold pressing pressure is 400 MPa and the cold pressing time is 1 min to obtain a green blank; S5: placing the green blank in a normal pressure furnace for sintering in air atmosphere. During sintering, firstly, heating from room temperature to 600°C at a rate of 0.6°C / min, keeping the temperature for 10 hours, then heating from 600°C to 1400°C at a rate of 1°C / min, keeping the temperature for 15 hours, then cooling to 1350°C at a rate of -3°C / min, keeping the temperature for 0.5 hours, and finally cooling from 1350°C to room temperature at a rate of -5°C / min to obtain a target material; S6: Processing the target material, the roughness of the processed target material is 0.4, and the processed target material is bound with metal indium, and the target material binding rate is 85%; In this embodiment, the tin oxide powder is prepared by a method comprising the following steps: (1) Weigh 50 g of a 20% aqueous solution of tin chloride pentahydrate and dissolve it in 250 mL of ethanol. Add 9.5 g of polyvinyl pyrrolidone while stirring. Add ammonia water dropwise to adjust the pH value to 10. React at 25°C for 2 h. Age for 12 h. Centrifuge the gel, remove the supernatant, wash with ethanol, centrifuge again, and wash with ethanol again. Repeat the centrifugation and washing until no chloride ions are detected in the supernatant to obtain a tin oxide precursor gel. (2) Place the tin oxide precursor gel in a high-pressure extraction autoclave for supercritical carbon dioxide extraction drying. Set the supercritical carbon dioxide flow rate to 50 mL / min, the temperature of the high-pressure extraction autoclave to 50 °C, the pressure to 10 MPa, and the extraction drying time to 7 h. After drying is completed, quickly release the pressure to atmospheric pressure, purge with dry air, cool to room temperature, and place the cooled powder in a muffle furnace for high-temperature treatment at 650 °C for 2 h to obtain the product.

[0031] Example 3 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this example includes the following steps: S1: Weigh 2 g of cerium oxide powder, 5 g of zinc oxide powder, 2 g of tantalum oxide powder, 4 g of ammonium polyacrylate, and 50 g of pure water, disperse for 30 min, and grind with a grinder at a speed of 1300 rpm for 100 min to obtain slurry A. The particle size D90 after grinding is 0.5 μm; S2: Weigh 991 g of tin oxide powder, 21 g of ammonium polyacrylate, and 950 g of pure water, disperse for 80 min, add slurry A, 200 g of polyvinyl alcohol, and 8 g of 2-nitrophenyloctyl ether, and grind with a grinder at a speed of 1300 rpm for 200 min to obtain slurry B. The particle size D90 after grinding is 0.4 μm; S3: Spray-dry slurry B, with an inlet air temperature of 200 °C, an outlet air temperature of 80 °C, and a rotation speed of 10000 rpm. After spray-drying, pass through a 100-mesh sieve to obtain doped powder; S4: Place the doped powder in a mold, first pre-press it with a hydraulic press, and then press it with a cold press. The pressure of the cold press is 300 MPa, and the cold press time is 60 min to obtain a green body; S5: Place the green body in an atmospheric furnace for sintering. The sintering atmosphere is air. During sintering, first heat from room temperature to 600 °C at a rate of 0.35 °C / min, hold for 8 h, then heat from 600 °C to 1350 °C at a rate of 0.55 °C / min, hold for 10 h, then cool to 1300 °C at a rate of -2 °C / min, hold for 1 h, and finally cool from 1300 °C to room temperature at a rate of -4 °C / min to obtain the target; S6: Process the target. The roughness of the processed target is 0.7. Bind the processed target with indium metal, and the target binding rate is 90% to obtain the product. The tin oxide powder in this example is prepared by a method including the following steps: (1) Weigh 50 g of a 20% aqueous solution of tin chloride pentahydrate and dissolve it in 250 mL of ethanol. Add 6 g of polyvinyl pyrrolidone while stirring. Add ammonia water dropwise to adjust the pH value to 10. React at 25°C for 4 h. Aged for 8 h. Centrifuge the gel, remove the supernatant, wash with ethanol, centrifuge again, and wash with ethanol again. Repeat the centrifugation and washing until no chloride ions are detected in the supernatant to obtain a tin oxide precursor gel. (2) The tin oxide precursor gel is placed in a high-pressure extraction kettle for supercritical carbon dioxide extraction and drying. The supercritical carbon dioxide flow rate is set to 30 mL / min, the temperature of the high-pressure extraction kettle is set to 45°C, the pressure is set to 12 MPa, and the extraction and drying time is set to 5 h. After drying, the pressure is quickly released to normal pressure and purged with dry air. The temperature is lowered to room temperature. The cooled powder is placed in a muffle furnace and treated at 600°C for 3 h to obtain the powder.

[0032] Example 4 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this embodiment is different from that in embodiment 3 in that: S1: Weigh 8 g of cerium oxide powder, 20 g of zinc oxide powder, 6 g of tantalum oxide powder, 4 g of ammonium polyacrylate and 50 g of pure water and disperse them for 30 min. Use a grinder to grind them at a speed of 1300 rpm for 100 min to obtain slurry A. The particle size D90 after grinding is 0.5 μm. S2: Weigh 966 g of tin oxide powder, 21 g of ammonium polyacrylate and 950 g of pure water, disperse for 80 min, add slurry A, 200 g of polyvinyl alcohol and 8 g of 2-nitrophenyl octyl ether, and grind at 1300 rpm for 200 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.4 μm; The remaining steps are the same as those in Example 3; The preparation method of tin oxide powder in this example is the same as that in Example 3.

[0033] Example 5 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this embodiment is different from that in embodiment 3 in that: S1: Weigh 5 g of cerium oxide powder, 10 g of zinc oxide powder, 4 g of tantalum oxide powder, 4 g of ammonium polyacrylate and 50 g of pure water and disperse them for 30 min. Use a grinder to grind at a speed of 1300 rpm for 100 min to obtain slurry A. The particle size D90 after grinding is 0.5 μm. S2: Weigh 981 g of tin oxide powder, 21 g of ammonium polyacrylate and 950 g of pure water, disperse for 80 min, add slurry A, 200 g of polyvinyl alcohol and 8 g of 2-nitrophenyl octyl ether, and grind at 1300 rpm for 200 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.4 μm; The remaining steps are the same as those in Example 3; The preparation method of tin oxide powder in this example is the same as that in Example 3.

[0034] Comparative Example Comparative Example 1 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target of this comparative example comprises the following steps: S1: Weigh 2g of cerium oxide powder, 5g of zinc oxide powder, 2g of tantalum oxide powder, 991g of tin oxide powder, 10g of sodium dodecyl sulfate and 1600g of pure water, disperse for 10min, add 50g of polyvinyl alcohol and 2g of 2-nitrophenyl octyl ether, grind at 1000rpm for 60min using a grinder to obtain a slurry, and the particle size D90 after grinding is 0.8μm; S2: spray drying the slurry, with an air inlet temperature of 160°C, an air outlet temperature of 50°C, and a rotation speed of 7000 rpm. After spray drying, the slurry is passed through a 40-mesh sieve to obtain a doped powder; S3: placing the doped powder in a mold, pre-pressing it with a hydraulic press, and then pressing it with a cold press. The cold pressing pressure is 200 MPa and the cold pressing time is 100 min to obtain a green blank; S4: placing the green blank in a normal pressure furnace for sintering in air atmosphere. During sintering, firstly, the temperature is raised from room temperature to 600°C at a rate of 0.1°C / min, and kept at this temperature for 5 hours. Then, the temperature is raised from 600°C to 1300°C at a rate of 0.1°C / min, and kept at this temperature for 3 hours. Then, the temperature is lowered to 1250°C at a rate of -1°C / min, and kept at this temperature for 1 hour. Finally, the temperature is lowered from 1250°C to room temperature at a rate of -3°C / min to obtain a target material. S5: Process the target material, the roughness of the processed target material is 1.0, and the processed target material is bound with metal indium, and the target material binding rate is 85%.

[0035] Comparative Example 2 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target of this comparative example comprises the following steps: S1: Weigh 2g of cerium oxide powder, 5g of zinc oxide powder, 2g of tantalum oxide powder, 3g of sodium dodecyl sulfate and 30g of pure water and disperse them for 10min, grind them at 1000rpm for 60min using a grinder to obtain slurry A, and the particle size D90 after grinding is 0.8μm; S2: Weigh 991 g of tin oxide powder, 7 g of sodium dodecyl sulfate and 1570 g of pure water, disperse for 30 min, add slurry A, 50 g of polyvinyl alcohol and 2 g of 2-nitrophenyl octyl ether, and grind at 1000 rpm for 300 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.6 μm; S3: spray drying slurry B, with an inlet air temperature of 160°C, an outlet air temperature of 50°C, and a rotation speed of 7000 rpm. After spray drying, the slurry is sieved through a 40-mesh sieve to obtain a doped powder; S4: placing the doped powder in a mold, pre-pressing it with a hydraulic press, and then pressing it with a cold press, the cold pressing pressure is 200 MPa, and the cold pressing time is 100 min to obtain a green blank; S5: placing the green blank in a normal pressure furnace for sintering in air atmosphere. During sintering, firstly, the temperature is raised from room temperature to 600°C at a rate of 0.1°C / min, and kept at this temperature for 5 hours. Then, the temperature is raised from 600°C to 1300°C at a rate of 0.1°C / min, and kept at this temperature for 3 hours. Then, the temperature is lowered to 1250°C at a rate of -1°C / min, and kept at this temperature for 1 hour. Finally, the temperature is lowered from 1250°C to room temperature at a rate of -3°C / min, and a target material is obtained. S6: Process the target material, the roughness of the processed target material is 1.0, and the processed target material is bound with metal indium, and the target material binding rate is 85%.

[0036] Comparative Example 3 The difference between the preparation method of the cerium-tantalum-zinc co-doped tin oxide target material in this comparative example and that in comparative example 2 is that S5: placing the green blank in a normal pressure furnace for sintering in air atmosphere. During sintering, firstly, heating from room temperature to 600°C at a rate of 0.1°C / min, keeping the temperature for 5 hours, then heating from 600°C to 1300°C at a rate of 0.1°C / min, keeping the temperature for 3 hours, and finally cooling from 1250°C to room temperature at a rate of -3°C / min to obtain a target material; The remaining steps are the same as those in Comparative Example 2.

[0037] Comparative Example 4 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this comparative example is different from that in comparative example 2 in that: S1: Weigh 0.5 g of cerium oxide powder, 5 g of zinc oxide powder, 0.5 g of tantalum oxide powder, 3 g of sodium dodecyl sulfate and 30 g of pure water, disperse for 10 min, and grind at 1000 rpm for 60 min using a grinder to obtain slurry A. The particle size D90 after grinding is 0.8 μm; S2: Weigh 994 g of tin oxide powder, 7 g of sodium dodecyl sulfate and 1570 g of pure water, disperse for 30 min, add slurry A, 50 g of polyvinyl alcohol and 2 g of 2-nitrophenyl octyl ether, and grind at 1000 rpm for 300 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.6 μm; The remaining steps are the same as those in Comparative Example 2.

[0038] Comparative Example 5 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this comparative example is different from that in comparative example 2 in that: S1: Weigh 15 g of cerium oxide powder, 5 g of zinc oxide powder, 10 g of tantalum oxide powder, 3 g of sodium dodecyl sulfate and 30 g of pure water, disperse for 10 min, and grind at 1000 rpm for 60 min using a grinder to obtain slurry A. The particle size D90 after grinding is 0.8 μm; S2: Weigh 970 g of tin oxide powder, 7 g of sodium dodecyl sulfate and 1570 g of pure water, disperse for 30 min, add slurry A, 50 g of polyvinyl alcohol and 2 g of 2-nitrophenyl octyl ether, and grind at 1000 rpm for 300 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.6 μm; The remaining steps are the same as those in Comparative Example 2.

[0039] Comparative Example 6 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this comparative example is different from that in comparative example 2 in that: S1: Weigh 2g of cerium oxide powder, 1g of zinc oxide powder, 2g of tantalum oxide powder, 3g of sodium dodecyl sulfate and 30g of pure water and disperse them for 10min, and grind them at 1000rpm for 60min using a grinder to obtain slurry A. The particle size D90 after grinding is 0.8μm; S2: Weigh 995 g of tin oxide powder, 7 g of sodium dodecyl sulfate and 1570 g of pure water, disperse for 30 min, add slurry A, 50 g of polyvinyl alcohol and 2 g of 2-nitrophenyl octyl ether, and grind at 1000 rpm for 300 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.6 μm; The remaining steps are the same as those in Comparative Example 2.

[0040] Comparative Example 7 The preparation method of the cerium-tantalum-zinc co-doped tin oxide target in this comparative example is different from that in comparative example 2 in that: S1: Weigh 2 g of cerium oxide powder, 30 g of zinc oxide powder, 2 g of tantalum oxide powder, 3 g of sodium dodecyl sulfate and 30 g of pure water, disperse for 10 min, and grind at 1000 rpm for 60 min using a grinder to obtain slurry A. The particle size D90 after grinding is 0.8 μm; S2: Weigh 969 g of tin oxide powder, 7 g of sodium dodecyl sulfate and 1570 g of pure water, disperse for 30 min, add slurry A, 50 g of polyvinyl alcohol and 2 g of 2-nitrophenyl octyl ether, and grind at 1000 rpm for 300 min using a grinder to obtain slurry B. The particle size D90 after grinding is 0.6 μm; The remaining steps are the same as those in Comparative Example 2.

[0041] Performance testing 1. Scanning electron microscope observation The doped powder prepared in the preparation process of the cerium-tantalum-zinc co-doped tin oxide target and the sintered target were observed by scanning electron microscope. The microscopic morphology is as follows: Figure 1 and Figure 2 shown.

[0042] 2. Density test The density test was carried out using the Archimedes drainage method, and the test results are shown in Table 1.

[0043] 3. Resistivity test The resistivity of the target material and the thin film sputtered from the target material was measured by a four-probe measurement method. The measurement results are shown in Table 1.

[0044] 4. Film mobility test The cerium-tantalum-zinc co-doped tin oxide targets prepared in Examples 1-5 and Comparative Examples 1-7 were used to deposit alloy films on quartz glass using a magnetron sputtering process. The film mobility was measured and calculated based on the Hall effect. The test results are shown in Table 1.

[0045] Table 1 Performance test results of target materials and sputtered films

[0046] Results Analysis It can be seen from the data of Comparative Examples 1-2 and Example 1 in Table 1 that when the oxide powder is dispersed and ground multiple times, the dispersibility is better, the relative density of the prepared target material is improved, the resistivity of the target material and the resistivity of the film sputtered by the target material are reduced, and the mobility of the sputtered film is improved. This may be because after the oxide powder is dispersed and ground multiple times, the powder particles have a smaller particle size and are not easy to agglomerate. During molding and sintering, the powder particles with better dispersibility produce smaller and fewer pores. Therefore, the compactness of the sintered target material is better, the relative density is reduced, and fewer pores are more conducive to the transmission of electrons, and the resistivity is reduced. The film sputtered by a target material with better density has fewer surface defects and higher mobility. When the wall surface area of ​​the tin oxide powder is larger and it is not easy to agglomerate, the relative density of the prepared target material is higher, the resistivity of the target material and the resistivity of the film sputtered by the target material are reduced, and the mobility of the sputtered film is increased. This may be because when the specific surface area of ​​the tin oxide powder is larger, there are more active sites, and the dispersion of cerium oxide, tantalum oxide and zinc oxide in it is better and the bonding force is stronger. After sintering, it is easier to densify and fewer crystal defects are produced. Therefore, the relative density is increased, the resistivity is reduced, and the mobility of the sputtered film is increased.

[0047] It can be seen from the data of Comparative Example 3 and Examples 1-3 in Table 1 that the sintering process has an important influence on the performance of the target material. This may be because the sintering process is an important part of the target material densification process. If the sintering curve is inappropriate, more pores and more crystal defects will be generated during sintering, resulting in a decrease in the density of the target material and an increase in the resistivity, which in turn affects the performance of the sputtered film.

[0048] It can be seen from the data of Comparative Examples 4-7 and Examples 1-5 in Table 1 that when the amount of cerium oxide, tantalum oxide and zinc oxide added is too little, fewer ions are provided and fewer oxygen vacancies are generated, so the mobility of the sputtered film is low and the resistivity is high; when the amount of cerium oxide, tantalum oxide and zinc oxide added is too much, the dispersibility may be deteriorated, more defects may be generated during molding and sintering, and the density may be reduced. Excessive doping may also enhance impurity scattering, increase resistivity and reduce mobility. Therefore, an appropriate amount of doping is more conducive to improving the performance of the target material and the sputtered film.

[0049] from Figure 1It can be seen intuitively that the doped powder in Comparative Example 1 shows obvious agglomeration phenomenon, large particles and small particles aggregate, irregular morphology, and poor dispersibility. In Example 1, Example 3, and Example 5, the doped powder is a relatively regular sphere, the particle distribution is relatively uniform, and the dispersibility is good. This is mainly due to: in the above embodiments, a step-by-step mixing method is adopted, and the tin oxide powder is prepared by the sol-gel method. First, cerium oxide powder, zinc oxide powder, tantalum oxide powder, etc. are made into slurry A, and then mixed with tin oxide, etc. At this time, the particles in slurry A have been preliminarily dispersed and refined, and can be more easily evenly distributed in the tin oxide system when mixed with tin oxide, thereby improving the overall dispersibility. In addition, the tin oxide powder prepared by the sol-gel method has special surface properties and particle morphology, which further helps the uniform dispersion of the mixed system. In Comparative Example 1, all powders are mixed at one time without step-by-step processing, which may cause some components to easily agglomerate and cannot be evenly dispersed in the entire system.

[0050] from Figure 2 It can be seen intuitively that the microstructures of Comparative Examples 1, 2, and 3 appear to be relatively rough and uneven, with many irregularly shaped areas. The microstructure of Example 5 is relatively more uniform. This is mainly due to: Figure 1 It can be seen that compared with Example 5 and Comparative Example 1, Example 5 adopts step-by-step grinding, first grinding and refining part of the raw materials separately, so that the particles are fully processed at different stages, reducing the tendency of agglomeration between particles and making it easier to distribute evenly. At the same time, Example 5 uses the sol-gel method to prepare tin oxide powder, which increases the roughness and surface area of ​​the tin oxide powder. Larger roughness and surface area can increase the interaction sites between powders, which helps to arrange and combine particles more closely and evenly in the subsequent mixing, pressing and sintering processes, thereby promoting the uniformity of the microstructure.

[0051] In contrast, in Comparative Example 1, all powders were mixed and ground at once, resulting in insufficient particle refinement and uneven dispersion, resulting in a rough and uneven microstructure. Although Comparative Examples 2 and 3 have improvements in the grinding step, they use ordinary tin oxide powder, which is inferior to the tin oxide powder prepared by the sol-gel method in terms of properties. In addition, there are differences in subsequent processes such as sintering, such as the lack of an intermediate heat preservation stage in Comparative Example 3. During the cooling process, the temperature inside the material changes unevenly, which also affects the uniformity of the microstructure.

[0052] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a cerium-tantalum-zinc co-doped tin oxide target, characterized in that: The steps include: S1: mixing cerium oxide powder, tantalum oxide powder, zinc oxide powder and water, adding a dispersant to disperse and grind to obtain slurry A; S2: mixing tin oxide powder with water, adding a dispersant for dispersion, adding slurry A, a binder and a plasticizer, grinding, and obtaining slurry B; S3: spray drying and sieving slurry B to obtain doped powder; S4: pressing and cold isostatically pressing the doped powder to obtain a green blank; S5: sintering the green blank in an air atmosphere to obtain a target material; S6: Process and bind the target material; The tin oxide powder is prepared by a method comprising the following steps: (1) An aqueous solution of tin chloride pentahydrate is mixed with ethanol, polyvinyl pyrrolidone is added, the pH is adjusted to 9-10, the mixture is reacted at room temperature for 2-5 hours, aged for 6-12 hours, and centrifuged and washed to obtain a tin oxide precursor gel; (2) The tin oxide precursor gel is extracted and dried by supercritical carbon dioxide, and then treated at 500-650° C. for 2-4 hours to obtain the tin oxide precursor gel.

2. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In steps S1 and S2, the dispersant is one or more of sodium dodecyl sulfate, sodium oleate and ammonium polyacrylate; the binder is polyvinyl acetate or polyvinyl alcohol; the plasticizer is polyethylene glycol or 2-nitrophenyl octyl ether; the mass ratio of the cerium oxide powder, tantalum oxide powder, zinc oxide powder and tin oxide powder is (0.2-0.8): (0.5-2): (0.2-0.6): (96.6-99.1); the mass ratio of the sum of the mass of the cerium oxide powder, tantalum oxide powder, zinc oxide powder and tin oxide powder, the total amount of pure water, the total amount of dispersant, the binder and the plasticizer is 100: (45-160): (1-4): (5-24): (0.2-1.2).

3. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step S1, the mass ratio of the sum of the masses of cerium oxide, tantalum oxide, zinc oxide, pure water, and dispersant is (9-34): (30-70): (3-12.5); the dispersion time is 10-60 min, the grinding speed is 1000-1800 rpm, the grinding time is 60-300 min, and the particle size after grinding D90 is ≤0.8 μm.

4. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step S2, the dispersion time is 30-120 min, the grinding speed is 1000-1800 rpm, the grinding time is 100-300 min, and the particle size after grinding is D90≤0.6 μm.

5. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step S3, the inlet air temperature of the spray drying is 160-250°C, the outlet air temperature is 50-130°C, the spray speed is 7000-15000rpm; and the mesh size of the sieving is 40-120 mesh.

6. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step S4, the pressing is first performed by pre-pressing with a hydraulic press, and then performed by pressing with a cold press, the cold pressing pressure is 200-400 MPa, and the cold pressing time is 1-100 min.

7. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step S5, the sintering is divided into a degreasing stage, a heating stage, and a cooling stage. In the degreasing stage, the temperature is raised from room temperature to 600°C at a rate of 0.1-0.6°C / min, and kept warm for 5-10h; in the heating stage, the temperature is first raised from 600°C to 1300-1400°C at a rate of 0.1-1°C / min, and kept warm for 3-15h, and then cooled to 1250-1350°C at a rate of -1 to -3°C / min, and kept warm for 0.5-1h; in the cooling stage, the temperature is cooled from 1250-1350°C to room temperature at a rate of -3°C to -5°C / min.

8. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step S6, the target material is processed to a surface roughness of 0.4-1.0, the binding material is metal indium, and the binding rate is ≥85%.

9. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step (1), the mass ratio of tin chloride pentahydrate to polyvinyl pyrrolidone is 100:(35-95).

10. The method for preparing a cerium-tantalum-zinc co-doped tin oxide target according to claim 1, characterized in that: In step (2), the conditions for supercritical carbon dioxide extraction and drying are: the flow rate of supercritical carbon dioxide is 15-50 mL / min, the temperature of the extraction kettle is 38-50° C., the pressure is 10-15 MPa, the extraction and drying time is 3-7 h, and after drying, the pressure is quickly released to normal pressure, and then purged with dry air to reduce the temperature to room temperature.

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