Preparation method of fine-grain high-strength indium-titanium-tantalum-cerium target

Abstract

The application discloses a fine-grain high-strength indium-titanium-tantalum-cerium oxide target material and a preparation method thereof. The preparation method comprises the following steps: (1) weighing indium oxide powder, titanium oxide powder, tantalum pentoxide powder and cerium oxide powder; (2) mixing and dispersing the weighed powder with a dispersing agent and a binder, and obtaining mixed slurry through wet grinding; (3) performing spray granulation on the mixed slurry as raw material to obtain mixed oxide powder; (4) performing compression molding to obtain a target blank; and (5) sequentially performing debinding sintering and two-stage normal-pressure sintering on the target blank to obtain the indium-titanium-tantalum-cerium oxide target material, wherein the two-stage normal-pressure sintering comprises the following steps: heating to 1400-1500 DEG C and maintaining for 5-10 h; cooling to 1320-1370 DEG C and maintaining for 35-50 h. The target material disclosed by the application has a more uniform microstructure, the grain size is significantly refined, and the bending strength is significantly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of target material preparation, and more particularly relates to a fine-grained high-strength indium-titanium-tantalum-cerium oxide target material and a preparation method thereof. BACKGROUND

[0002] Oxide semiconductor thin films have excellent photoelectric properties such as wide band gap, low resistance, high light transmittance in the visible light region, and high light reflectance in the infrared spectrum region, and have been widely used in the fields of solar cells, flat panel displays, organic light-emitting diodes, low-emissivity glass, special functional window coatings, transparent thin-film transistors, and flexible electronic devices for a long time.

[0003] At present, indium-titanium-tantalum-cerium oxide films are widely used in HJT heterojunction cells as TCO layers between amorphous silicon and electrodes to improve the lateral collection of carriers and the transfer to front and back metals. As the sputtering raw material of the TCO layer, the average use period of the oxide tantalum-cerium target material is about thirty days, and it takes 2-3 days to replace the new target / sputtering shield to restore production. In order to reduce the production downtime caused by target replacement, heterojunction cell manufacturers gradually use larger outer diameter, higher weight, and longer use period target materials to replace the original small outer diameter target materials. With a significant increase in the weight of the target material, higher torque is required to drive the target material to rotate during sputtering. At this time, if the strength of the target material is low, there is a risk of target cracking during long-term use, which puts new demands on the mechanical properties such as bending strength of the indium-titanium-tantalum-cerium oxide target material.

[0004] The mechanical properties of oxide target materials are closely related to their microstructure, especially the size of the grain size. Generally, the smaller the grain size, the better the material toughness and the higher the strength. As a sintering process in the preparation of target materials, the traditional debinding-sintering-cooling sintering method often uses a higher sintering temperature and a longer holding time to ensure the densification of the target material, which leads to irregular grain growth and the formation of uneven microstructure at the end of sintering.

[0005] The traditional debinding-sintering-cooling sintering method can easily lead to abnormal grain growth and the formation of uneven microstructure in the target material during the late sintering period, resulting in a decrease in the mechanical properties such as bending strength of the target material and a high risk of target cracking. SUMMARY

[0006] In view of the above problems in the prior art, the purpose of the present application is to provide a fine-grained high-strength indium-titanium-tantalum-cerium oxide target material and a preparation method thereof.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0008] A preparation method of a fine-grained high-strength indium-titanium-tantalum-cerium oxide target material, comprising the following steps:

[0009] (1) Take indium oxide powder, titanium oxide powder, tantalum pentoxide powder, and cerium oxide powder by mass ratio of 95.5-97.5:0.3-2.0:0.3-2.0:0.3-1.5, respectively;

[0010] (2) Mix and disperse the powders taken in step (1) with a dispersant and a binder to obtain a mixed slurry through wet grinding;

[0011] (3) Spray granulation is performed with the mixed slurry as raw material to obtain a mixed oxide powder;

[0012] (4) The mixed oxide powder is used as raw material for compression molding to obtain a target blank;

[0013] (5) The target blank is sequentially subjected to debinding sintering and two-stage atmospheric sintering to obtain an indium titanium tantalum cerium oxide target material, wherein the two-stage atmospheric sintering comprises:

[0014] Rising to 1400-1500℃ for 5-10h, and then lowering to 1320-1370℃ for 35-50h.

[0015] Further, in step (1), the purity of the indium oxide powder, the titanium oxide powder, the tantalum pentoxide powder, and the cerium oxide powder is 4N.

[0016] Further, the dispersant is one or more of triethylhexyl phosphoric acid, polyvinylpyrrolidone, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, a polycarboxylic acid compound, polyvinyl acetate, or sodium cetylbenzenesulfonate.

[0017] Preferably, the binder is one or more of polyethylene glycol, polyvinyl butyral, carboxymethyl cellulose, polyacrylamide, and polyacrylic acid.

[0018] Further, in step (2), the mass of the dispersant added is 0.5-1.0% of the total mass of the oxide powders, the dispersant, and the binder; and the mass of the binder added is 2.0-3.0% of the total mass of the oxide powders, the dispersant, and the binder.

[0019] Further, the solid content of the mixed slurry is 50-60%.

[0020] Further, in step (3), spray granulation is performed using a spray drying tower. The powder obtained after spray granulation is subjected to homogenizing screening to obtain a mixed oxide powder with uniform particle size distribution.

[0021] Further preferably, the particle size of the mixed oxide powder is required to be D50 of 40-60μm and D90 of 70-100μm.

[0022] Further, in step (4), the compression molding is performed by using post-molding cold isostatic pressing;

[0023] Preferably, the compression pressure is 30-100 Mpa, and the compression time is 40-120 s.

[0024] Preferably, the cold isostatic pressing pressure is 150-400 Mpa, and the compression time is 30-180 s.

[0025] Further, in step (8):

[0026] The debinding heat treatment is: in air atmosphere, the temperature is raised to 500-700 ℃ at a temperature raising rate of 0.5-1 ℃ / min, and the temperature is kept for 2-5 h.

[0027] The two-stage normal pressure sintering is: in oxygen atmosphere, the temperature is raised to 1400-1500 ℃ at a temperature raising rate of 0.6-1.2 ℃ / min, and the temperature is kept for 5-10 h; the temperature is lowered to 1320-1370 ℃ at a temperature lowering rate of 1-1.5 ℃ / min, and the temperature is kept for 35-50 h.

[0028] The application further discloses the indium titanium tantalum cerium oxide target prepared by the preparation method.

[0029] Further, the indium titanium tantalum cerium oxide target has a grain size of less than or equal to 8 μm, a relative density of more than or equal to 99.5%, and a bending strength of more than or equal to 160 Mpa.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] The application creatively proposes a two-step sintering process for preparing the indium titanium tantalum cerium oxide target. By this method, the microstructure of the obtained target becomes more uniform, and the grain size is significantly refined, thereby significantly improving the bending strength. Specifically, in the one-step sintering, the sintering in the later stage will cause the grain to grow rapidly due to the too fast grain boundary migration caused by the long time of keeping the temperature in the high temperature section. The target prepared by the two-step sintering method is firstly sintered at a higher temperature to make the target obtain a certain density, and then the difference between the grain boundary migration energy and the grain boundary diffusion energy is utilized to ensure the grain boundary diffusion while inhibiting the grain boundary migration in the set temperature range, thereby inhibiting the grain growth and obtaining a more uniform and refined microstructure.

[0032] The indium titanium tantalum cerium oxide target prepared by the preparation method has a significantly improved strength, and can meet the demand of the application scenarios with higher strength requirements. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application together with the embodiments thereof, and explain the application without limiting the application. In the drawings:

[0034] Figure 1 Metallographic picture of the target material obtained in Comparative Example 1;

[0035] Figure 2 Column chart of grain size distribution of the target material obtained in Comparative Example 1;

[0036] Figure 3 Metallographic picture of the target material obtained in Example 1;

[0037] Figure 4 Column chart of grain size distribution of the target material obtained in Example 1;

[0038] Figure 5 Metallographic picture of the target material obtained in Comparative Example 2;

[0039] Figure 6 Column chart of grain size distribution of the target material obtained in Comparative Example 2;

[0040] Figure 7 Metallographic picture of the target material obtained in Example 2;

[0041] Figure 8 Column chart of grain size distribution of the target material obtained in Example 2. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present application, the following will be a more comprehensive and detailed description of the present application in conjunction with the drawings and preferred embodiments of the specification, but the protection scope of the present application is not limited to the following specific embodiments.

[0043] Unless otherwise defined, all the professional terms used in the following have the same meaning as that generally understood by those skilled in the art. The professional terms used in this paper are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present application.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0045] Example 1

[0046] (1) 50 kg of indium oxide, titanium oxide, tantalum oxide and cerium oxide powders were accurately weighed according to the mass ratio of 96.5:0.5:2.0:1.0.

[0047] (2) The powders weighed in step (1) were added to a dispersion tank with 350 g of polyvinylpyrrolidone and 1050 g of polyvinyl butyral for dispersion, and the dispersion conditions were 90 rpm for 40 min. The dispersed powder was pumped into a sand mill for wet sanding at 1000 rpm for 120 min to obtain a mixed slurry with a solid content of 60%.

[0048] (3) The slurry obtained in step (2) is sprayed and granulated in a spray drying tower. The powder is homogenized and sieved to obtain a mixed oxide powder with uniform particle size distribution. The D50 of the mixed oxide powder is 43 μm and the D90 is 79 μm.

[0049] (4) The mixed oxide powder obtained in step (3) is added to the mold, and the target blank is obtained by molding and cold isostatic pressing. The molding pressure is 60 MPa and the pressing time is 100 s. The cold isostatic pressing pressure is 180 MPa and the pressing time is 70 s.

[0050] (5) Place the target blank obtained in step (4) into a sintering furnace, heat it to 600℃ at a rate of 0.5℃ / min, hold it in an air atmosphere for 3 hours, continue to heat it to 1450℃ at a rate of 0.7℃ / min, hold it in an oxygen atmosphere for 8 hours, and continue to cool it to 1370℃ at a rate of 1.5℃ / min, hold it in an oxygen atmosphere for 35 hours. Obtain the indium titanium tantalum cerium target material.

[0051] The indium titanium tantalum cerium target material prepared in this embodiment has a relative density of 99.45%, a grain size of 6.92 μm, and a bending strength of 175 MPa.

[0052] Comparative Example 1

[0053] (1) Weigh out 50 kg of indium oxide, titanium oxide, tantalum oxide and cerium oxide powder in a mass ratio of 96.5:0.5:2.0:1.0.

[0054] (2) The powder weighed in step (1) is added to a dispersion tank along with 350g of polyvinylpyrrolidone and 1050g of polyvinyl butyral for dispersion at a speed of 80 rpm for 30 min. The dispersed powder is then pumped into a sand mill for wet sand milling at 1100 rpm for 60 min to obtain a mixed slurry with a solid content of 60%.

[0055] (3) The slurry obtained in step (2) is sprayed and granulated in a spray drying tower. The powder is homogenized and sieved to obtain a mixed oxide powder with uniform particle size distribution. The D50 of the mixed oxide powder is 47 μm and the D90 is 82 μm.

[0056] (4) The mixed oxide powder obtained in step (3) is added to the mold, and the target blank is obtained by molding and cold isostatic pressing. The molding pressure is 60 MPa and the pressing time is 100 s. The cold isostatic pressing pressure is 180 MPa and the pressing time is 70 s.

[0057] (5) Place the target blank obtained in step (4) into a sintering furnace, heat it to 600℃ at 0.5℃ / min, hold it for 3h, and continue to heat it to 1380℃ at 0.7℃ / min, hold it for 20h. Obtain indium titanium tantalum cerium target material.

[0058] The indium titanium tantalum cerium target material prepared in this embodiment has a relative density of 99.35%, a grain size of 12.78 μm, and a bending strength of 142 MPa.

[0059] Figure 1 , Figure 2 The images shown are metallographic images of the target material obtained in Comparative Example 1 and a bar chart showing the grain size distribution of the target material. Figure 3 , Figure 4 The images shown are metallographic images and grain size distribution histograms of the target material obtained in Example 1. It can be seen that the preparation method of this application can obtain an indium titanium tantalum cerium target material with a more uniform and refined microstructure, and its strength is also significantly improved.

[0060] Comparative Example 2

[0061] (1) Weigh out 50 kg of indium oxide, titanium oxide, tantalum oxide and cerium oxide powder in a mass ratio of 96.5.0:1.0:1.5:1.0.

[0062] (2) The powder weighed in step (1) is added to a dispersion tank along with 350g of polyvinylpyrrolidone and 1050g of polyvinyl butyral for dispersion at a speed of 80 rpm for 30 min. The dispersed powder is then pumped into a sand mill for wet sand milling at 1100 rpm for 60 min to obtain a mixed slurry with a solid content of 60%.

[0063] (3) The slurry obtained in step (2) is sprayed and granulated in a spray drying tower. The powder is homogenized and sieved to obtain a mixed oxide powder with uniform particle size distribution. The D50 of the mixed oxide powder is 53 μm and the D90 is 82 μm.

[0064] (4) The mixed oxide powder obtained in step (3) is added to the mold, and the target blank is obtained by molding and cold isostatic pressing. The molding pressure is 60 MPa and the pressing time is 100 s. The cold isostatic pressing pressure is 180 MPa and the pressing time is 70 s.

[0065] (5) The target blank obtained in step (4) is placed in a sintering furnace and heated to 600°C at a rate of 0.5°C / min. It is then kept in an air atmosphere for 3 hours. The temperature is then increased to 1530°C at a rate of 0.7°C / min and kept in an oxygen atmosphere for 8 hours. Finally, the temperature is decreased to 1380°C at a rate of 1.5°C / min and kept for 35 hours to obtain an indium titanium tantalum cerium target.

[0066] The indium tantalum cerium oxide target material prepared in this comparative example has a relative density of 99.24%, a grain size of 15.25 μm, and a bending strength of 135 MPa.

[0067] Example 2

[0068] (1) Weigh out 50 kg of indium oxide, titanium oxide, tantalum oxide and cerium oxide powder in a mass ratio of 96.5:1.0:1.5:1.0.

[0069] (2) The powder weighed in step (1) is added to a dispersion tank along with 350g of polyvinylpyrrolidone and 1050g of polyvinyl butyral for dispersion at a speed of 80 rpm for 30 min. The dispersed powder is then pumped into a sand mill for wet sand milling at 1100 rpm for 60 min to obtain a mixed slurry with a solid content of 60%.

[0070] (3) The slurry obtained in step (2) is sprayed and granulated in a spray drying tower. The powder is homogenized and sieved to obtain a mixed oxide powder with uniform particle size distribution. The D50 of the mixed oxide powder is 53 μm and the D90 is 76 μm.

[0071] (4) The mixed oxide powder obtained in step (3) is added to the mold, and the target blank is obtained by molding and cold isostatic pressing. The molding pressure is 60 MPa and the pressing time is 100 s. The cold isostatic pressing pressure is 180 MPa and the pressing time is 70 s.

[0072] (5) Place the target blank obtained in step (4) into a sintering furnace, heat it to 600℃ at a rate of 0.5℃ / min, hold it in air atmosphere for 3 hours, continue to heat it to 1430℃ at a rate of 0.7℃ / min, hold it in oxygen atmosphere for 8 hours, and continue to cool it to 1350℃ at a rate of 1.5℃ / min, hold it in oxygen atmosphere for 35 hours. Obtain indium titanium tantalum cerium target material.

[0073] The indium tantalum cerium oxide target material prepared in this comparative example has a relative density of 99.28%, a grain size of 7.45 μm, and a bending strength of 167 MPa.

[0074] Figure 5 , Figure 6 The images shown are metallographic images of the target material obtained in Comparative Example 2 and a bar chart showing the grain size distribution of the target material. Figure 7 , Figure 8 The images shown are metallographic images and grain size distribution graphs of the target material obtained in Example 2. It can be seen that the preparation method of this application can obtain an indium titanium tantalum cerium target material with a more uniform and refined microstructure, and its strength is also significantly improved.

[0075] The above are merely preferred embodiments of the present invention and are not intended to limit the 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 the present invention.

Claims

1. A method for preparing a fine-grained, high-strength indium titanium tantalum cerium target, characterized in that, Includes the following steps: (1) Weigh out indium oxide powder, titanium oxide powder, tantalum pentoxide powder and cerium oxide powder respectively in a mass ratio of 95.5~97.5:0.3~2.0:0.3~2.0:0.3~1.5; (2) The powder weighed in step (1) is mixed and dispersed with the dispersant and binder, and then wet-milled to obtain a mixed slurry; (3) Spray granulation is performed using the mixed slurry as raw material to obtain mixed oxide powder; (4) The mixed oxide powder is pressed and molded to obtain the target blank; (5) The target blank is subjected to degreasing sintering and two-stage atmospheric pressure sintering in sequence to obtain indium titanium tantalum cerium target material, wherein the two-stage atmospheric pressure sintering includes: Heat to 1400~1500℃ and hold for 5~10 hours; Cool down to 1320~1370℃ and keep warm for 35~50 hours.

2. The preparation method according to claim 1, characterized in that, In step (1), the purity of indium oxide powder, titanium oxide powder, tantalum pentoxide powder, and cerium oxide powder is 4N.

3. The preparation method according to claim 1, characterized in that, The dispersant is one or more of the following: triethylhexylphosphonic acid, polyvinylpyrrolidone, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polycarboxylic acid compounds, polyvinyl salts, and sodium hexadecylbenzene sulfonate; The adhesive is one or more of polyethylene glycol, polyvinyl butyral, carboxymethyl cellulose, polyacrylamide, and polyacrylic acid.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass of the dispersant is 0.5 to 1.0% of the total mass of the oxide powder, dispersant, and binder; the mass of the binder is 2.0 to 3.0% of the total mass of the oxide powder, dispersant, and binder.

5. The preparation method according to claim 1 or 4, characterized in that, The solid content of the mixed slurry is 50-60%.

6. The preparation method according to claim 1, characterized in that, In step (3), a spray drying tower is used for spray granulation; the powder obtained after spray granulation is homogenized and sieved to obtain a mixed oxide powder with uniform particle size distribution.

7. The preparation method according to claim 1, characterized in that, In step (4), the molding process is carried out by first molding and then cold isostatic pressing.

8. The preparation method according to claim 7, characterized in that, The molding pressure is 30~100Mpa; the pressing time is 40~120s.

9. The preparation method according to claim 7, characterized in that, The cold isostatic pressing pressure is 150~400Mpa, and the pressing time is 30~180s.

10. The preparation method according to claim 1, characterized in that, In step (5): The degreasing heat treatment is as follows: in an air atmosphere, the temperature is increased to 500℃~700℃ at a heating rate of 0.5~1℃ / min, and held for 2~5 hours; The two-stage atmospheric pressure sintering process is as follows: in an oxygen atmosphere, the temperature is increased to 1400~1500℃ at a heating rate of 0.6~1.2℃ / min and held for 5~10h; then the temperature is decreased to 1320~1370℃ at a cooling rate of 1~1.5℃ / min and held for 35~50h.

11. An indium titanium tantalum cerium target material prepared by the preparation method according to any one of claims 1 to 10.

12. The indium titanium tantalum cerium target material according to claim 11, characterized in that, The indium titanium tantalum cerium target has a grain size ≤8μm, a relative density ≥99%, and a bending strength ≥160Mpa.

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