Preparation method of high-density low-indium-content ITO target material

Abstract

A preparation method of high-density low-indium-content ITO target material, comprising the following steps: (1) mixing indium oxide and tin oxide micro-nano powder according to the indium content, then adding sintering aid antimony trioxide, uniformly mixing and grinding, and forming a green body; (2) after the green body is degreased, sintering is performed to obtain the ITO target material with high density (relative density >= 99.5%), low resistivity (<= 1*10 ‑3 Ω*cm) and low indium content (40.5-42%). The indium content is further reduced and the resistivity is reduced by tin doping on the In4Sn3O2 material. The relative density of the target material is improved by adding a suitable proportion of sintering aid and sintering at high temperature for a short time.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a metal oxide ceramic target material for magnetron sputtering coating, in particular to a preparation method of a high-density low-indium-content ITO target material. BACKGROUND

[0002] The indium tin oxide (ITO) target material is a kind of semiconductor ceramic functional material, which is used for magnetron sputtering coating of ITO thin film. As a kind of transparent conductive material, the ITO thin film is widely used in the fields of display and touch control, and is also partially applied in the industries of solar energy and Low-E glass. The commonly used ITO thin film has a mass ratio of indium oxide to tin oxide of 90:10, and the indium content is as high as 74.4%. Metal indium is a kind of rare and precious metal, and the high indium content leads to a high cost of the ITO target material, which seriously affects the popularization and application of the ITO material in the non-display fields such as solar energy and Low-E glass.

[0003] Typical low-indium ITO materials include In2SnO5 and In4Sn3O2, and the indium contents are 53.6% and 45.6% respectively. The patent “Indium tin oxide ternary compound target material, preparation method and application thereof” (patent application number: CN202310409407.9) discloses a low-indium ITO target material with an In4Sn3O2 composition, and the indium content is 43.5-55.7%, the relative density is greater than or equal to 98%, and the resistivity is less than or equal to 5*10 -3 Ω·cm. However, the market demands a low-indium ITO target material with a higher relative density and a lower resistivity, so it is necessary to develop a preparation process of a high-density low-resistivity low-indium ITO target material. SUMMARY

[0004] The technical problem to be solved by the application is to provide a preparation method of a high-density low-indium-content ITO target material. The method further reduces the indium content by tin doping of the In4Sn3O2 material, and the relative density of the target material is increased to more than 99.5% by adding a suitable proportion of sintering aid, so that a low-indium-content ITO target material with a lower resistivity is obtained, and the resistivity is less than or equal to 1*10 -3 Ω·cm.

[0005] The technical solution for solving the above technical problems is a preparation method of a high-density low-indium-content ITO target material, which comprises the following steps:

[0006] (1) Indium oxide micro-nano powder and tin oxide micro-nano powder are mixed in a mass fraction of 40.5%-42% of indium content, and then 2.5%-5% of the total amount of indium oxide and tin oxide of sintering aid antimony trioxide is added, a slurry with a mass solid content of 35%-44% is prepared, and the mixture is uniformly ground; and a green body with a relative density of greater than or equal to 53% is formed;

[0007] (2) After the obtained green body is debinded, sintering is carried out; the sintering process is as follows: first, the temperature is raised to 1280-1320°C at a rate of 0.5-2°C / min, and then the temperature is kept for 20-40 hours, then the temperature is raised to 1630-1650°C, and then the temperature is kept for 3-6 hours, then the temperature is lowered to 900-1100°C at a rate of 2.5-5°C / min, and finally the temperature is lowered naturally; during the process, oxygen is supplied when the temperature is raised to 500-600°C, and the oxygen supply is stopped when the temperature is lowered to 1400-1450°C; after the temperature in the furnace is lowered to room temperature, the target material is taken out of the furnace, and thus a high-density ITO target material with low indium content is obtained.

[0008] Further, the relative density of the prepared ITO target material is ≥99.5%.

[0009] Further, the resistivity of the prepared ITO target material is ≤1×10 -3 Ω·cm.

[0010] Further, granulation and die molding and cold isostatic pressing are adopted in step (1).

[0011] Further, injection molding or other conventional methods are adopted in step (1).

[0012] Further, the diameters of the indium oxide micro-nano powder and the tin oxide micro-nano powder in step (1) are less than 3μm.

[0013] In the preparation process of the present application, a proper amount (2.5-5%) of antimony oxide, a sintering aid, is added, which is beneficial to the densification of the target material in the early stage of sintering, and improves the sintering density of the target material; and the added antimony oxide will volatilize in the low-temperature stage (1280-1320°C) for a long time. The high-temperature sintering of the target material, which is not lower than the melting point of tin oxide (1630°C), is beneficial to reducing and eliminating a large number of pores left by the volatilization of antimony oxide, and improving the density. The volatilization of indium oxide and tin oxide will result in a decrease in density, and the high-temperature short-time sintering for 3-6 hours is beneficial to avoiding the excessive volatilization caused by the long-time high-temperature volatilization of indium oxide and tin oxide.

[0014] The ITO target material is an electronic ceramic, and the purity requirement is high. The added sintering aid can be completely volatilized in the subsequent process, and the residual amount of antimony element is ≤1ppm, so the addition of the sintering aid has basically no effect on the purity of the prepared ITO target material.

[0015] Thanks to the above technical solutions, the present application can prepare an ITO target material with high density (relative density ≥99.5%), low resistivity (≤1×10 -3 Ω·cm), and low indium content (40.5-42%).

[0016] In the following, the technical features of the preparation method of the high-density ITO target material with low indium content will be further described in combination with examples. DETAILED DESCRIPTION Example 1

[0017] The indium oxide and tin oxide micro-nano powders were mixed in a mass fraction of 40.5% of indium content, and then 5% of the total amount of indium oxide and tin oxide of the sintering aid antimony trioxide was added, to form a slurry with a mass solid content of 44%, which was uniformly mixed and ground. Granulation and cold isostatic pressing were used for molding, and the relative density of the green body after molding was 56%.

[0018] The obtained green body was debound and then sintered. The sintering process was as follows: heating at 0.5°C / min to 1280°C, holding for 40 hours; then heating to 1650°C, holding for 3 hours. Then, the temperature was decreased to 1100°C at a rate of 2.5°C / min. Then, the temperature was naturally decreased with the furnace. During the process, oxygen was supplied when the temperature reached 500°C, and the oxygen supply was stopped when the temperature reached 1450°C. After the furnace temperature decreased to room temperature, the target material was taken out of the furnace. The relative density of the target material was 99.5%, and the resistivity was 0.83 x 10 -3 Ω·cm, and the residual amount of antimony was ≤1 ppm. Example 2

[0019] The indium oxide and tin oxide micro-nano powders were mixed in a mass fraction of 42% of indium content, and then 2.5% of the total amount of indium oxide and tin oxide of the sintering aid antimony trioxide was added, to form a slurry with a mass solid content of 35%, which was uniformly mixed and ground. Injection molding was used for molding, and the relative density of the green body after drying was 53%.

[0020] The obtained green body was debound and then sintered. The sintering process was as follows: heating at 2°C / min to 1320°C, holding for 20 hours; then heating to 1630°C, holding for 6 hours. Then, the temperature was decreased to 900°C at a rate of 5°C / min. Then, the temperature was naturally decreased with the furnace. During the process, oxygen was supplied when the temperature reached 600°C, and the oxygen supply was stopped when the temperature reached 1400°C. After the furnace temperature decreased to room temperature, the target material was taken out of the furnace. The relative density of the target material was 99.7%, and the resistivity was 0.72 x 10 -3 Ω·cm, and the residual amount of antimony was ≤1 ppm. Example 3

[0021] The indium oxide and tin oxide micro-nano powders were mixed in a mass fraction of 41.5% of indium content, and then 3.5% of the total amount of indium oxide and tin oxide of the sintering aid antimony trioxide was added, to form a slurry with a mass solid content of 40%, which was uniformly mixed and ground. Granulation and cold isostatic pressing were used for molding, and the relative density of the green body after molding was 56%.

[0022] The obtained green body is debound and then sintered. The sintering process is as follows: heating to 1300 DEG C at a rate of 1 DEG C / min and keeping for 30 hours; then heating to 1640 DEG C and keeping for 4.5 hours. Then, the temperature is decreased to 1000 DEG C at a rate of 3.5 DEG C / min. Then, the temperature is decreased naturally. During the process, oxygen is supplied when the temperature is increased to 550 DEG C, and the oxygen supply is stopped when the temperature is decreased to 1430 DEG C. After the temperature of the furnace is decreased to room temperature, the target material is taken out of the furnace. The relative density of the target material is 99.6%, and the resistivity is 0.78*10 -3 Ω*cm, and the residual amount of antimony element is less than or equal to 1 ppm.

[0023] In the embodiments of the present application, the diameters of the indium oxide micro-nano powder and the tin oxide micro-nano powder are less than 3 μm. The debinding temperature is about 600 DEG C, which is a conventional temperature in the industry.

[0024] Comparative Example 1:

[0025] The indium oxide micro-nano powder and the tin oxide micro-nano powder are mixed according to the mass fraction of 45% of indium content, the amount of the sintering aid is 0, the intermediate holding point is 900 DEG C for 8 hours, and the other steps are the same as those in Example 2. After the temperature of the furnace is decreased to room temperature, the target material is taken out of the furnace. The relative density of the target material is 98.4%, and the resistivity is 3.88*10 -3 Ω*cm.

[0026] Comparative Example 2:

[0027] The indium oxide micro-nano powder and the tin oxide micro-nano powder are mixed according to the mass fraction of 45% of indium content, and the other steps are the same as those in Example 2. After the temperature of the furnace is decreased to room temperature, the target material is taken out of the furnace. The relative density of the target material is 99.5%, and the resistivity is 1.63*10 -3 Ω*cm.

[0028] Comparative Example 3:

[0029] The indium oxide micro-nano powder and the tin oxide micro-nano powder are mixed according to the mass fraction of 40% of indium content, and the other steps are the same as those in Example 2. After the temperature of the furnace is decreased to room temperature, the target material is taken out of the furnace. The relative density of the target material is 99.1%, and the resistivity is 1.23*10 -3 Ω*cm.

[0030] Comparative Example 4:

[0031] The amount of the sintering aid is 2%, and the other steps are the same as those in Example 2. After the temperature of the furnace is decreased to room temperature, the target material is taken out of the furnace. The relative density of the target material is 99.0%, and the resistivity is 0.98*10 -3 Ω*cm.

[0032] Comparative Example 5:

[0033] The fluxing agent is added in an amount of 6%, and other steps are the same as those in Example 2. After the furnace temperature is reduced to room temperature, the target material is discharged from the furnace. It is measured that the relative density of the target material is 97.8%, and the resistivity is 4.87 x 10 -3 Ω·cm.

[0034] Comparative Example 6:

[0035] The slurry solid content is 50% by weight, and other steps are the same as those in Example 2. After the furnace temperature is reduced to room temperature, the target material is discharged from the furnace. It is measured that the relative density of the target material is 98.1%, and the resistivity is 2.32 x 10 -3 Ω·cm.

[0036] Comparative Example 7:

[0037] The intermediate section holding point is set to 1200℃, and other steps are the same as those in Example 2. After the furnace temperature is reduced to room temperature, the target material is discharged from the furnace. It is measured that the relative density of the target material is 97.3%, and the resistivity is 4.26 x 10 -3 Ω·cm.

[0038] Comparative Example 8:

[0039] The intermediate section holding point is set to 1350℃, and other steps are the same as those in Example 2. After the furnace temperature is reduced to room temperature, the target material is discharged from the furnace. It is measured that the relative density of the target material is 98.8%, and the resistivity is 3.41 x 10 -3 Ω·cm.

[0040] Comparative Example 9:

[0041] The highest temperature holding point is set to 1620℃, and other steps are the same as those in Example 2. After the furnace temperature is reduced to room temperature, the target material is discharged from the furnace. It is measured that the relative density of the target material is 96.3%, and the resistivity is 9.24 x 10 -3 Ω·cm.

[0042] Comparative Example 10:

[0043] The highest temperature holding point is set to 1680℃, and other steps are the same as those in Example 2. After the furnace temperature is reduced to room temperature, the target material is discharged from the furnace. It is measured that the relative density of the target material is 97.6%, and the resistivity is 4.18 x 10 -3 Ω·cm.

[0044] Comparison Table of Process Parameters and Product Performance Parameters of Examples and Comparative Examples of the Invention

[0045]

[0046] Note: The target material resistivity requirement is ≤1 x 10 -3 Ω·cm, and the relative density requirement is ≥99.5%.

[0047] In the table, R represents that the result meets the requirements, and Q represents that the result does not meet the requirements.

Claims

1. A method for preparing a high-density low-indium-content ITO target material, characterized by: The method comprises the following steps: (1) mixing indium oxide micro-nano powder and tin oxide micro-nano powder according to the indium content of 40.5%-42% by mass fraction, then adding 2.5%-5% of the total amount of sintering aid antimony trioxide to the indium oxide and tin oxide, preparing slurry with mass solid content of 35%-44%, and uniformly mixing and grinding; forming a green body with relative density of ≥53%; (2) after the green body is debound, sintering is performed; the sintering process is: first, heating at a rate of 0.5-2 ℃ / min to 1280-1320 ℃, maintaining for 20-40 hours, then heating to 1630-1650 ℃, maintaining for 3-6 hours, then cooling at a rate of 2.5-5 ℃ / min to 900-1100 ℃, and finally naturally cooling with the furnace; during the process, oxygen is started to be supplied when the temperature is raised to 500-600 ℃, and the oxygen supply is stopped when the temperature is lowered to 1400-1450 ℃; after the furnace temperature is lowered to room temperature, the target material is taken out of the furnace, and a high-density low-indium-content ITO target material is obtained.

2. The method of claim 1, wherein the method further comprises: The prepared ITO target material has a relative density of ≥99.5%. ​ 3. The method of claim 1, wherein the method further comprises: The prepared ITO target has resistivity ≤1×10 -3 Ω·cm. ​ 4. The method of producing a high-density low-indium-content ITO target according to any one of claims 1 to 3, characterized in that: In step (1), granulation and cold isostatic pressing are adopted for forming.

5. The method of producing a high-density low-indium-content ITO target according to any one of claims 1 to 3, characterized in that: In step (1), injection molding or other conventional methods are adopted for forming.

6. The method of claim 1-3, wherein the method of producing a high-density low-indium-content ITO target is characterized by: In step (1), the diameter of the indium oxide micro-nano powder and the tin oxide micro-nano powder is less than 3 μm.

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