JPH10203875A - Production of ceramic sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic sintered compact in a high yield by making an R-processing of a specified length or longer on the edges of a ceramic powder compact followed by sintering the compact so as not to develop any cracks on the edges of the (un)sintered compact. SOLUTION: This ceramic sintered compact is essentially composed, for example, of zinc, aluminum and oxygen, or strontium, titanium and oxygen, and obtained by making an R-processing of 0.2-3mm long on the edges of a ceramic powder compact followed by sintering the compact. For a sintered compact essentially composed of indium, tin and oxygen (ITO), the amount of tin oxide is set at 5-15wt.% so as to decrease the resistivity of an ITO thin film formed by sputtering. Specifically, this ceramic sintered compact is obtained by the following process: mixed powder or solid solution powder of desired ceramic stock powder is ground and subjected to compaction, as necessary, pressed into a mold together with water and a binder to form a compact, the respective edges of which are subjected to R-processing >=0.2mm in length followed by conducting a sintering operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a ceramic sintered body suitable for a sputtering target.

[0002]

2. Description of the Related Art Sputtering targets made of ceramic sintered bodies have been used to form thin films in various fields. For example, ITO (Indium Ti
n Oxide) thin film has features such as high conductivity and high transmittance, and can be easily micro-processed.
It is used in a wide range of fields such as display electrodes for flat panel displays, window materials for solar cells, and antistatic films. In particular, in the field of flat panel displays such as liquid crystal display devices, the size and definition are increasing,
The demand for an ITO thin film as the display electrode is also rapidly increasing.

[0003] However, the price of ceramics sintered products such as ITO is relatively high, and as the range of application expands, demands for lower prices are increasing from the market.

[0004] As one method for achieving a reduction in cost, it is conceivable to improve the production yield of ceramic sintered bodies. To date, cracks and cracks at the edge of the compact or the edge of the sintered compact, which occur during the manufacturing process, are known as factors that reduce the yield.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a ceramic sintered body having a high production yield.

[0006]

The inventors of the present invention have analyzed the causes of cracks generated from the edges of the sintered body. (2) When a compact having such small cracks is sintered, the cracks expand due to shrinkage during sintering, and in some cases, cracks occur in the sintered body. (3) It has been found that the edge portion of the molded body receives heat from above and from the measurement during sintering, so that it shrinks faster than other portions and micro cracks are easily expanded.

Therefore, based on the above findings, further experiments were conducted by focusing on the shape of the edge portion of the molded body and the processing method. As a result, when the molded body was processed into a shape satisfying certain conditions, cracks generated during sintering were observed. The inventors have found that the occurrence rate is remarkably reduced and the production yield of the ceramic sintered body is improved, and the present invention has been completed.

That is, the present invention relates to a method for producing a ceramic sintered body, which comprises subjecting an edge portion of a molded body formed of ceramic powder to a rounding process of 0.2 mm or more, followed by sintering. is there.

Hereinafter, the present invention will be described in detail.

Although the ceramic sintered body of the present invention is not particularly limited, for example, a sintered body (ZAO) substantially consisting of zinc, aluminum and oxygen, and substantially consisting of strontium, titanium and oxygen Sintered body (STO), sintered body substantially composed of strontium, barium, titanium and oxygen (BST), sintered body substantially composed of indium, tin and oxygen (ITO), substantially bismuth, tantalum, A sintered body (SBT) made of strontium and oxygen can be used.

The ceramic sintered body of the present invention is obtained by sintering a ceramic molded body having a specific edge portion. In the case of ITO, the amount of tin oxide is 5 to 15 wt.% So that the specific resistance value of the ITO thin film obtained by sputtering decreases. % Is desirable.

The compact in the present invention can be obtained, for example, by molding a mixed powder of a raw material powder (oxide powder) of a desired ceramic sintered body or a solid solution powder.

For example, a compact for obtaining ZAO is made from a mixed powder of zinc oxide and aluminum oxide by STO.
The molded body for obtaining BST was obtained from a mixed powder of strontium carbonate and titanium oxide.
A compact for obtaining ITO from a mixed powder of strontium carbonate, barium carbonate and titanium oxide is made of bismuth oxide, and a compact for obtaining SBT is made of a mixed powder of indium oxide and tin oxide or a solid solution powder of indium oxide and tin oxide. And a mixed powder of tantalum oxide and strontium carbonate.

More specifically, these raw material powders are subjected to pulverization or consolidation treatment as necessary, and then molded by a molding method such as a press method or a casting method to produce a molded body.

In the case of producing a molded article by press molding, after filling the above-mentioned powder into a mold of a predetermined size, the molded article is pressed with a press at a pressure of 100 to 1000 kg / cm ^2. I do. At this time, a binder such as polyvinyl alcohol and paraffin may be added to the raw material powder as needed.

On the other hand, in the case of producing a molded article by casting, the powder is mixed with water, a binder and a dispersing agent to form a slurry, and the thus obtained powder is mixed with 50 to 5,000.
A slurry having a viscosity of centipoise is poured into a casting mold at a pressure of ¹ to 50 kg / cm ² to produce a molded body.

In order to prevent cracks and cracks after sintering, each edge of the ceramic molded body thus obtained is 0.2 mm or more, preferably 0.2 to 3 mm.
The edge is chamfered by performing an R process of mm.

Further, the R-processed compact may be subjected to a consolidation treatment by a cold isostatic press (CIP), if necessary. At this time, the pressure of the CIP is preferably ² ton / cm ² or more in order to obtain a sufficient consolidation effect. When the molding is performed by the casting method, a drying treatment and a debinding treatment are performed at a temperature of 300 to 500 ° C. for about 5 to 20 hours to remove moisture and organic substances such as a binder remaining in the molded body after the CIP. It is preferable to apply. Also, even when molding is performed by the press method,
When a binder is used at the time of molding, it is desirable to perform the same binder removal treatment.

The thus obtained compact is sintered in a sintering furnace. The sintering atmosphere is not particularly limited, and may be, for example, in the air or in an oxidizing atmosphere. The sintering temperature and time can be appropriately set by those skilled in the art to obtain a sufficient density increasing effect. For example, in order to obtain ITO, 1400 ° C. or more,
3 hours or more, ZAO, STO, B
In order to obtain ST, the temperature is preferably set to 1300 to 1500 ° C. for 3 hours or more.
It is desirable to set the temperature at 0 to 1400 ° C. for 3 hours or more.

The crack generation rate of the sintered body manufactured by the above method is reduced, and the production yield is improved.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0022] 10wt Example 1 SnO _2. % Of the mixed powder of indium oxide and tin oxide was placed in a mold having a diameter of 200 mm.
Pressing was performed at a pressure of 250 kg / cm ² to produce 20 molded bodies. After subjecting these compacts to CIP treatment at a pressure of 3 ton / cm ² ,
A 0.2 mm round process was performed. Next, these 20 compacts were placed in a pure oxygen atmosphere sintering furnace and sintered.

No cracks or cracks occurred from the edges in any of the obtained sintered bodies, and the yield was 20/20 =
100%.

Comparative Example 1 Twenty sintered bodies were produced in the same manner as in Example 1 except that the R processing was not performed on the edge portion of the molded body. Cracks from the edges were observed in the five sintered bodies after sintering, and the production yield was 15/20 = 75%.

Example 2 BaCO ₃ was added in an amount of 39.1 wt. %, SrCO ₃ 29.2w
t. % And TiO ₂ are 31.7 wt. % Mixed powder was used as a raw material powder. The resultant powder mixture was placed in a mold having a diameter of 200 mm, 200 kg / cm ²
And pressed to produce 20 molded bodies. After subjecting these compacts to CIP treatment at a pressure of 3 ton / cm ² , the edges of the compacts were subjected to a 0.2 mm rounding process. Next, these 20 compacts were placed in a pure oxygen atmosphere sintering furnace and sintered.

No cracks or cracks were generated from the edges of any of the obtained sintered bodies, and the yield was 20/20 =
100%.

Comparative Example 2 Twenty sintered bodies were produced in the same manner as in Example 1 except that the R processing was not performed on the edge portion of the molded body. Cracking from the edge portion was observed in the eight sintered bodies after sintering, and the production yield was 12/20 = 60%.

[0028]

By producing a ceramic sintered body by the method of the present invention, cracks and cracks from the edges do not occur in the sintered body after sintering, and the production yield can be greatly improved. .

[0029]

Claims (27)

[Claims] 1. A method for producing a ceramic sintered body, comprising: subjecting an edge portion of a molded body formed of ceramic powder to a rounding process of 0.2 mm or more, followed by sintering. 2. The method for producing a ceramic sintered body according to claim 1, wherein an R process of 0.2 to 3 mm is performed. 3. The method for producing a ceramic sintered body according to claim 1, wherein the molded body is substantially made of zinc, aluminum and oxygen. 4. The method for producing a ceramic sintered body according to claim 3, wherein the sintering is performed in the air or in an oxidizing atmosphere. 5. The method for producing a ceramic sintered body according to claim 3, wherein the sintering is performed at 1300 to 1500 ° C. for 3 hours or more. 6. The method for producing a ceramic sintered body according to claim 1, wherein the molded body substantially consists of strontium, titanium, and oxygen. 7. The method for producing a ceramic sintered body according to claim 6, wherein the sintering is performed in the air or in an oxidizing atmosphere. 8. The method for producing a ceramic sintered body according to claim 6, wherein the sintering is performed at 1300 to 1500 ° C. for 3 hours or more. 9. The method for producing a ceramic sintered body according to claim 1, wherein the molded body is substantially composed of strontium, barium, titanium, and oxygen. 10. The method for producing a ceramic sintered body according to claim 9, wherein the sintering is performed in the air or in an oxidizing atmosphere. 11. The method for producing a ceramic sintered body according to claim 9, wherein the sintering is performed at 1300 to 1500 ° C. for 3 hours or more. 12. The method for producing a ceramic sintered body according to claim 1, wherein the molded body is substantially composed of bismuth, tantalum, strontium and oxygen. 13. The method for producing a ceramic sintered body according to claim 12, wherein the sintering is performed in the air or in an oxidizing atmosphere. 14. The method for producing a ceramic sintered body according to claim 12, wherein the sintering is performed at 900 to 1400 ° C. for 3 hours or more. 15. The method for producing a ceramic sintered body according to claim 1, wherein the molded body is substantially composed of indium, tin and oxygen. 16. The molded product obtained by molding a mixed powder of an indium oxide powder and a tin oxide powder.
6. The method for producing a ceramic sintered body according to 5. 17. The method for producing a ceramic sintered body according to claim 15, wherein the molded body is formed by molding indium tin oxide solid solution powder. 18. The amount of tin oxide in the compact is 5 to 15 watts.
t. The method for producing a ceramic sintered body according to any one of claims 15 to 17, wherein the percentage is%. 19. The method for producing a ceramic sintered body according to claim 15, wherein the molded body is obtained by press molding. 20. Press molding is performed at 100 to 1000 kg /
The method for producing a ceramic sintered body according to claim 19, wherein the method is performed at a pressure of cm ² . 21. The method for producing a ceramic sintered body according to claim 15, wherein the molded body is obtained by cast molding. 22. The method for producing a ceramic sintered body according to claim 21, wherein the casting is performed at a pressure of 1 to 50 kg / cm ² . 23. The ceramic sintering method according to claim 15, wherein a cold isostatic pressing (CIP) is further performed on the R-processed compact before the sintering step. The method of manufacturing the aggregate. 24. The method for producing a ceramic sintered body according to claim 23, wherein the CIP is performed at a pressure of 1 ton / cm ² or more. 25. The molded product after the CIP is further subjected to 300 to 5
The method according to claim 2, wherein the treatment is performed at 00C for 5 to 20 hours.
The method for producing a ceramic sintered body according to claim 3 or 24. 26. The method for producing a ceramic sintered body according to claim 15, wherein the sintering is performed in the air or in an oxidizing atmosphere. 27. The method according to claim 15, wherein the sintering is performed at 1400 ° C. or more for 3 hours or more.