A method for preparing indium cerium oxide target and its application

Abstract

This invention belongs to the field of coating materials technology and provides a method for preparing indium cerium oxide (ICE) target materials and their applications. The invention involves mixing metal oxides In₂O₃ and CeO₂ with salts in a specific ratio, calcining the mixture to obtain ICE powder, then adding water and a first dispersant to obtain a slurry, spray drying to obtain granulated powder, followed by molding and cold isostatic pressing to obtain a green blank, and finally sintering to obtain the ICE target material. The ICE target material prepared by this invention has high density (>99%), high uniformity (resistivity difference between different regions of the target material is less than or equal to 3.5%), and long service life (more than 160 hours). It solves the problem that Ce is difficult to completely dissolve in the In₂O₃ lattice, easily leading to the presence of a second crystalline phase CeO₂, which severely reduces the uniformity of the target material. Furthermore, the preparation process of this invention is simple and easy to control, with low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of coating materials technology, and more specifically, to a method for preparing an indium cerium oxide target and its application. Background Technology

[0002] Transparent conductive oxide (TCO) thin films exhibit high transmittance in the visible-near infrared band and high reflectivity in the mid-far infrared band, while also possessing excellent conductivity. They are widely used in display devices, solar cells, infrared imaging, spacecraft, and optical coatings. Magnetron sputtering deposition, which involves bombarding a target with high-energy ions to deposit atoms or molecules from the target onto a substrate surface, forms a thin film. This technique offers advantages such as fast deposition rates, high film density, and strong compositional controllability, making it suitable for large-area industrial production and widely used.

[0003] Currently, most transparent conductive oxide thin films are prepared using Sn-doped In₂O₃ (ITO) targets. However, ITO-based TCO films have low mobility and poor infrared transmittance, making them unsuitable for applications such as solar cells. Ce-doped In₂O₃ (indium cerium oxide target, or ICO)-based TCO films, while possessing high mobility and transmittance, can effectively compensate for the shortcomings of ITO, and TCO films prepared using ICO targets exhibit excellent photoelectric properties. However, during the sintering of ICO targets, Ce... 4+ It is difficult for the target material to enter the In2O3 lattice, and the second crystalline phase CeO2 is prone to exist, which reduces the uniformity of the target material, thereby reducing the quality of the obtained film and shortening its service life. Moreover, when the target material has poor uniformity, blackening nodules and cracking may occur during magnetron sputtering, which also directly reduces the coating quality and shortens the service life of the target material. Chinese patent (publication number CN119637931A) provides a method for preparing indium cerium oxide powder and target material based on electrochemical method. It uses an electrolytic method to prepare a mixture of In(OH)3 and Ce(OH)4, and then pyrolyzes it to obtain ICO powder, and then prepares ICO target material. Compared with ICO target material prepared by using In2O3 and CeO2 as raw materials, the ICO target material has better uniformity and longer service life. However, this electrolytic method uses In-Ce alloy as raw material. Since metallic Ce has a lower reduction potential, Ce will preferentially form during electrolysis. 4+ This leads to the formation of Ce(OH)4 first, resulting in a clear sequence in the precipitation processes of In(OH)3 and Ce(OH)4. This causes certain differences in the composition of each precipitate mixture, making it difficult to obtain precipitates with high uniformity. In addition, electrolytic preparation consumes a lot of energy, which is not conducive to green production.

[0004] Therefore, there is an urgent need to develop a method to improve the uniformity of indium cerium oxide (ICO) targets, reduce CeO2 residue in the targets, improve coating quality, extend the lifespan of the targets, and reduce energy consumption. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing indium cerium oxide (ICO) targets and its applications. The preparation method provided by this invention has low energy consumption, can improve the uniformity of the obtained ICO targets, has high target density (>99%), high uniformity (resistivity difference between different regions of the target is less than or equal to 3.5%), and long service life (more than 160 hours).

[0006] The first aspect of the present invention provides a method for preparing an indium cerium oxide target.

[0007] Specifically, a method for preparing an indium cerium oxide target includes the following steps:

[0008] (1) Mix metal oxides and salts, and then calcine them to obtain indium cerium oxide powder;

[0009] The salts are solid at room temperature, but melt at 800-1000℃ to form an ionic melt;

[0010] (2) The indium cerium oxide powder, water, and the first dispersant are mixed, ground, and a slurry is obtained. The slurry is then spray-dried to obtain granulated powder.

[0011] (3) The granulated powder is injected into a mold for molding, and after demolding, it is subjected to cold isostatic pressing to obtain a green blank;

[0012] (4) The green blank is sintered to obtain the indium cerium oxide target material;

[0013] The metal oxides include In₂O₃ and CeO₂;

[0014] The mass ratio of the metal oxide to the salt is 1:3-10.

[0015] This invention uses metal oxides In₂O₃ and CeO₂, along with salts, to prepare ICO powder. The presence of salts provides a liquid-phase reaction environment during calcination, promoting uniform collision of reactants and facilitating CeO₂ reaction. 4+ When it enters the In2O3 lattice, it is not easy to form the second crystalline phase CeO2, thereby significantly improving the uniformity of the metal oxide and enhancing the quality and service life of the target material.

[0016] Preferably, the purity of the metal oxide is greater than or equal to 4N.

[0017] Preferably, the weight ratio of In2O3 to CeO2 is (90-99.5):(10-0.5).

[0018] Preferably, the median particle size (Dv) of the In2O3 is... 50 (less than or equal to 2μm)

[0019] Preferably, the median particle size (Dv) of the CeO2 is... 50 (less than or equal to 2μm)

[0020] Preferably, the salt is at least one selected from alkali metal halides, alkali metal nitrates, alkali metal sulfates, alkaline earth metal halides, alkaline earth metal nitrates, and alkaline earth metal sulfates.

[0021] Preferably, the alkali metal halide is NaCl and / or KCl.

[0022] Preferably, the alkali metal nitrate is NaNO3 and / or KNO3.

[0023] Preferably, the alkali metal sulfate is Na2SO4 and / or K2SO4.

[0024] Preferably, the alkaline earth metal halide is at least one of MgBr2, CaCl2, and BaCl2.

[0025] Preferably, the alkaline earth metal nitrate is at least one of Mg(NO3)2, Ca(NO3)2, and Ba(NO3)2.

[0026] Preferably, the sulfate of the alkaline earth metal is at least one of MgSO4, CaSO4, and BaSO4.

[0027] Na in salts + K + and Ca 2+ It cannot be incorporated into indium oxide to avoid reducing the uniformity of the target material, and is applicable to this invention.

[0028] Preferably, in step (1), In2O3 and CeO2 are first mixed, and then salts are added and ground and mixed.

[0029] Preferably, in step (1), the calcination temperature is 800-1000℃, and / or the calcination time is 3-10h.

[0030] Preferably, in step (1), after calcination, the powder is cooled and then washed with water until the Cl content in the powder is reduced. - Na + K + and Ca 2+The ion content was all <15ppm.

[0031] Preferably, in step (2), a second dispersant and a plasticizer are added to the slurry, and then spray drying is performed to obtain granulated powder.

[0032] Preferably, in step (2), the first dispersant and the second dispersant are each independently selected from at least one of polyvinylpyrrolidone (PVP), ammonium polyacrylate, polyacrylamide, and polymethyl methacrylate.

[0033] Preferably, in step (2), the plasticizer is at least one of polyethylene glycol (PEG), acrylic acid, and carboxymethyl cellulose.

[0034] Preferably, in step (2), the spray drying temperature is 120-180°C, and / or the spray drying flow rate is 5-50 L / h.

[0035] Preferably, in step (2), the median particle size (Dv) of the slurry is... 50 ≤0.30μm.

[0036] Preferably, in step (2), the moisture content of the granulated powder is 0.3-0.8%.

[0037] Preferably, in step (3), the molding pressure is 20-80 MPa.

[0038] Preferably, in step (3), the pressure of the cold isostatic pressing is 120-200 MPa, and / or the time of the cold isostatic pressing is 5-30 min.

[0039] Preferably, in step (4), the sintering includes the following steps:

[0040] First, the blank is heated to 600-900℃ and held for 2-6 hours; then the temperature is increased to 1300-1600℃ while oxygen is introduced and held for 3-20 hours. After the holding period, the temperature is reduced to room temperature to obtain the indium cerium oxide target.

[0041] More preferably, in step (4), the sintering includes the following steps:

[0042] First, the blank is heated to 600-900℃ at a rate of 0.5-3℃ / min and held for 2-6 hours; then the temperature is increased to 1300-1600℃ while oxygen is introduced at a rate of 5-50L / min and held for 3-20 hours. After the holding period, the temperature is reduced to room temperature at a rate of 0.5-3℃ / min to obtain the indium cerium oxide target.

[0043] A second aspect of the present invention provides an application of a method for preparing an indium cerium oxide target.

[0044] Application of a method for preparing indium cerium oxide target material in the fields of photovoltaic cells, displays or semiconductors.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] This invention involves mixing metal oxides In₂O₃ and CeO₂ with salts in a specific ratio, calcining the mixture to obtain indium cerium oxide powder, then adding water and a first dispersant to obtain a slurry, spray drying to obtain granulated powder, followed by molding and cold isostatic pressing to obtain a green blank, and finally sintering to obtain an indium cerium oxide target. The preparation method of this invention has low energy consumption, is simple and easy to control, and produces an indium cerium oxide target with high density (>99%), high uniformity (resistivity difference between different regions of the target is less than or equal to 3.5%), and long service life (more than 160 hours). It solves the problem that Ce is difficult to completely dissolve in the In₂O₃ lattice, and the second crystalline phase CeO₂ is prone to exist, which seriously reduces the uniformity of the target. Detailed Implementation

[0047] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0048] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0049] Example 1

[0050] A method for preparing an indium cerium oxide (ICO) target material includes the following steps:

[0051] (1) First, In₂O₃ (purity 99.99%, median particle size 1.5 μm) and CeO₂ (purity 99.99%, median particle size 1.5 μm) were mixed, followed by the addition of salts. The pre-mixed powder was then thoroughly ground and mixed evenly. The mixed powder was then placed in a corundum crucible and calcined at 900℃ for 6 hours. After holding at this temperature, the crucible was cooled. The resulting powder was stirred in deionized water for 3 hours, with the water changed 3 times, until the Cl content in the powder decreased. - Na + K + and Ca 2+ The ion content is <15ppm. The detection method is: ICP is used to characterize the impurity content in the powder to obtain ICO powder.

[0052] (2) Mix ICO powder, water, and polyvinylpyrrolidone (PVP, dispersant), and ball mill using a sand mill for 5 hours. The median particle size Dv of the slurry is... 50The particle size was ≤0.30μm. Then, 0.8wt% PVA and 0.5wt% PEG of ICO powder were added to the slurry. After stirring for 3 hours, the spray drying temperature was adjusted to 150℃ and the flow rate was 30L / h to obtain granulated powder with a moisture content of 0.5%.

[0053] (3) The granulated powder is injected into a metal mold for molding. The molding pressure is 50 MPa. After demolding, it is placed in a cold isostatic pressing equipment and held under a pressure of 150 MPa for 10 minutes. After depressurization, a green blank with a relatively high density is obtained.

[0054] (4) Sintering the green blank: raise the temperature to 700℃ at a rate of 1.5℃ / min and hold for 5h; continue to raise the temperature to 1580℃ at the same time, while introducing oxygen at a rate of 20L / min and holding at the same temperature for 5h. After the holding period, lower the temperature to room temperature at a rate of 1.5℃ / min to obtain the ICO target material.

[0055] Examples 2-6

[0056] Examples 2-6 provide ICO targets, which differ from Example 1 in that the raw material composition is different. The preparation method is the same as in Example 1, except that the sintering temperature is different, as shown in Table 1.

[0057] Comparative Example 1

[0058] An ICO target material, which differs from Example 4 in that no salts are added in step (1).

[0059] Comparative Example 2

[0060] An ICO target material, which differs from Example 5 in that no salts are added in step (1).

[0061] Comparative Example 3

[0062] An ICO target material differs from Example 4 in that the amount of salt used in step (1) is reduced so that the weight ratio of metal oxide to salt is 1:1.

[0063] Product effectiveness test

[0064] Density: The density of the ICO target was tested using the Archimedes displacement method.

[0065] Resistivity: The resistivity of the target material was tested using the four-probe method.

[0066] The resistivity difference rate is calculated as follows: 10 sites are randomly selected on the target material, their resistivity is tested, and the maximum and minimum values ​​are compared. The difference rate between the two is the maximum difference rate.

[0067] Target lifespan: This refers to the time it takes for the target to undergo continuous coating until severe abnormalities such as nodulation, blackening, or cracking occur. The coating process is as follows: magnetron sputtering is used, with a coating power of 6kW and a coating temperature of 180℃.

[0068] Table 1. Raw material composition and target material performance parameters for each embodiment and comparative example.

[0069]

[0070] As shown in the table above, the ICO targets prepared in Examples 1-6 all achieved high density (>99%), and the resistivity difference between different regions of the target was less than or equal to 3.5%, indicating excellent uniformity. Furthermore, their service life was all above 160 hours. Compared to the ICO targets prepared in Comparative Examples 1-3, the targets prepared in Examples 1-6 exhibited higher uniformity and longer service life.

[0071] Comparative Examples 1 and 2 were prepared using conventional methods for ICO targets. Comparative Example 1 did not add salts. Although it could also achieve a high density, the resistivity difference between different regions of the target was >10%, resulting in poor uniformity. This led to a significantly shorter lifespan of the target compared to Examples 4 and 5 with the same formulation.

[0072] Comparative Example 3 added less molten salt, making it difficult to form a molten liquid phase. As a result, the uniformity of the obtained ICO powder was poor, and the uniformity and service life of the target material were worse than those of Examples 1-6.

Claims

1. A method for preparing an indium cerium oxide target, characterized in that, Includes the following steps: (1) Mix metal oxides and salts, and then calcine them to obtain indium cerium oxide powder; The salts are solid at room temperature and melt at 800-1000℃ to form an ionic melt; (2) The indium cerium oxide powder, water, and the first dispersant are mixed, ground, and a slurry is obtained. The slurry is then spray-dried to obtain granulated powder. (3) The granulated powder is injected into a mold for molding, and after demolding, it is subjected to cold isostatic pressing to obtain a green blank; (4) The green blank is sintered to obtain the indium cerium oxide target material; The metal oxides include In₂O₃ and CeO₂; The mass ratio of the metal oxide to the salt is 1:3-10. In step (4), the sintering includes the following steps: First, the blank is heated to 600-900℃ and held for 2-6 hours; then the temperature is increased to 1300-1600℃ while oxygen is introduced and held for 3-20 hours. After the holding period, the temperature is reduced to room temperature to obtain the indium cerium oxide target.

2. The preparation method according to claim 1, characterized in that, The weight ratio of In2O3 to CeO2 is (90-99.5):(10-0.5).

3. The preparation method according to claim 1, characterized in that, The salt is at least one of alkali metal halides, alkali metal nitrates, alkali metal sulfates, alkaline earth metal halides, alkaline earth metal nitrates, and alkaline earth metal sulfates.

4. The preparation method according to claim 1, characterized in that, In step (1), the calcination temperature is 800-1000℃, and / or the calcination time is 3-10h.

5. The preparation method according to claim 1, characterized in that, In step (2), the spray drying temperature is 120-180℃, and / or the spray drying flow rate is 5-50L / h.

6. The preparation method according to claim 1, characterized in that, In step (2), the median particle size of the slurry is ≤0.30μm, and / or the moisture content of the granulated powder is 0.3-0.8%.

7. The preparation method according to claim 1, characterized in that, In step (3), the molding pressure is 20-80 MPa.

8. The preparation method according to claim 1, characterized in that, In step (3), the pressure of the cold isostatic pressing is 120-200 MPa, and / or the time of the cold isostatic pressing is 5-30 min.

9. The application of the method for preparing the indium cerium oxide target according to any one of claims 1-8 in the fields of photovoltaic cells, displays or semiconductors.

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