JPH09111444A - Production of indium oxide-zinc oxide based sintered body target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of an indium oxide-zinc oxide based sintered body target capable of obtaining the target high in relative density even if the sintered body having a large size is produced and suppressing the generation of a color shading at a peripheral part and a center part of the sintered body. SOLUTION: In a production method of the indium oxide-zinc oxide based sintered body target, a zinc oxide powder is calcined at 400-800 deg.C, and the calcined zinc oxide power is mixed with an indium oxide powder, then after press molding this powdery mixture, the molded matter is sintered at 1,200-1,400 deg.C. A BET surface area of the zinc oxide powder after calcinating is kept in 0.2-4.0m<2> /g. A temp. raising speed to a sintering temp. at a sintered stage is kept in >=350 deg.C/hr.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an indium oxide-zinc oxide based sintered body target used as a material for forming a transparent conductive film.

[0002]

2. Description of the Related Art Liquid phase display devices (LCDs) are currently in use.
Indium oxide-tin oxide (ITO) is widely used as a transparent conductive film material for display devices such as. The ITO transparent conductive film is usually produced by a sputtering method using an ITO sintered body target. This ITO film is an excellent material such as low resistance, excellent transparency, and good etching property, but it has a problem of low moisture resistance.

Japanese Patent Laid-Open No. 6-234565 discloses a sintered body target made of an indium oxide-zinc oxide based material as a material having improved moisture resistance and having conductivity and transparency equivalent to that of ITO. Proposed. Although the method for producing a sintered body disclosed in Japanese Patent Laid-Open No. 6-234565 targets relatively small articles,
The size of the sintered compact target used in actual industrial production is much larger than this. When a large-sized sintered body having a size of, for example, 5 inches × 15 inches or more is produced by such a conventional manufacturing method, a sufficiently high-density sintered body (relative density of 95% or more) cannot be obtained. There are still problems such as uneven color in the peripheral part and the central part. In particular, when a target with uneven color is used for sputtering, the resistance value of the obtained film varies, so in practice, the outer part of the sintered body is ground to remove the uneven color before use as a target. is the current situation.

[0004]

According to the present invention, even when a large-sized sintered body is produced, a high density having a relative density of 90% or more can be obtained, and the color of the peripheral portion and the central portion of the sintered body is high. It is an object of the present invention to provide a method for manufacturing an indium oxide-zinc oxide based sintered compact target in which unevenness is suppressed.

[0005]

The present invention is characterized by the following items. The zinc oxide powder is calcined at 400 ° C. to 800 ° C., the calcined zinc oxide powder and the indium oxide powder are mixed, and the mixed powder is press-molded at 1200 ° C. to 1 ° C.
A method for manufacturing an indium oxide-zinc oxide based sintered body target, which is sintered at 400 ° C. The BET surface area of the zinc oxide powder after calcination is 0.2 to
The method for producing a target as described above, wherein the target is 4.0 m ² / g. The rate of raising the temperature to the sintering temperature in the sintering process is 3
The method for producing a target according to 1) or 2) above 50 ° C./hour or more. The method for producing a target according to 1 to 3, wherein the composition of the sintered body is 50% by weight or more of indium oxide.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The manufacturing method of the present invention will be described in detail below. First, only zinc oxide powder is calcined prior to mixing the raw material zinc oxide (ZnO) and indium oxide (In ₂ O ₃ ) powders. The purpose of calcining the zinc oxide powder is to cause the powder particles to grow into particles by the calcining and reduce the activity as powder. Calcination temperature is 40
The temperature is 0 to 800 ° C, preferably 400 to 600 ° C. This is because the higher the calcination temperature, the stronger the particles are coagulated, and the more difficult the subsequent crushing is. The calcination time is preferably 2 hours or more.

Next, the obtained zinc oxide calcined powder is mixed with indium oxide. As a mixing method, a known method such as a ball mill is adopted. A known composition can be applied to the mixing ratio of zinc oxide and indium oxide. A binder is added as necessary during or after the mixing of these powders, and then press molding is performed by means such as cold isostatic pressure (CIP).

Further, the obtained molded body is heated at 1200 ° C to 1 ° C.
Sinter at a temperature of 400 ° C. This gives a relative temperature of 9
A sufficiently high density sintered body target of 0% or more can be obtained. If the sintering temperature is 1200 ° C. or less, the sintered body does not have a high density, and if it exceeds 1400 ° C., ZnO sublimes, resulting in composition unevenness or composition deviation. The sintering time is preferably 2 hours or more. Next, the sintered body is subjected to surfacing processing by surface grinding and mechanical processing for cutting the outer peripheral portion for removing the uneven color portion to obtain a product target.

The method of manufacturing an In ₂ O ₃ —ZnO-based sintered body target of the present invention is characterized in that only the ZnO powder is calcined prior to mixing the In ₂ O ₃ and ZnO powders. The ZnO powder is calcined in order to suppress color unevenness that is expected to be caused by the nonstoichiometry of oxygen. That is, zinc oxide originally exhibits an oxygen-deficient non-stoichiometric property, and thus calcining this reduces the activity as powder and makes it difficult for oxygen to enter and exit. If calcination is performed in a state of being mixed with indium oxide, the activity of the indium oxide powder is also reduced, and it becomes difficult to sufficiently densify in the subsequent sintering step, and a high density sintered body target cannot be obtained.

Zinc oxide after calcination has a BET surface area of 0.2.
Color unevenness can be effectively suppressed in the range of up to 4.0 m ² / g. Further, if the rate of raising the temperature to the sintering temperature in the sintering step is 350 ° C./hour or more, it is possible to ensure that a sufficient high density (relative density of 95% or more) is obtained,
In particular, the rate of temperature increase between 800 ° C and the sintering temperature (1200 ° C to 1400 ° C) is important. Furthermore, when the composition of the target is 50 wt% or more of indium oxide, the effect of increasing the density (95% or more in relative density) and suppressing color unevenness is particularly remarkable.

[0011]

The present invention will be further described below with reference to examples and comparative examples. As shown in Table 1, after the zinc oxide powder was calcined at each calcining temperature for 2 hours, the calcined zinc oxide powder and the indium oxide powder were mixed to each composition, and zirconia (ZrO ₂ ) balls were formed. Use a ball mill to dry 2
Mix for 4 hours. Then, an aqueous PVA solution was added to this mixture as a binder, and the size was 5 inches x 15 inches x 18 m.
A m-thick flat plate was press-formed with a pressure of 800 kgf / cm ² using a mold. Sintering time of the obtained compact is 8
It was fired under various sintering conditions in the air for a time.

Table 1 shows the calcination conditions, the sintering conditions and the results of various tests. Regarding the determination of color unevenness, the weight that must be removed to remove the color unevenness portion by grinding to obtain a target without color unevenness exceeds 30% of the weight of the sintered body immediately after firing. Is x and 30
The ones that were completed within% were rated as ○.

[0013]

[Table 1]

As can be seen from the test results shown in Table 1, all of the sintered bodies of Examples 1 to 4 which are within the manufacturing conditions of the present invention have high density and less uneven coloring. on the other hand,
In Comparative Example 1 in which the calcination temperature and the BET surface area are outside the manufacturing conditions of the present invention, color unevenness occurs, and in the Comparative Example 2 in which the sintering temperature is out of the range, only a sintered body having a low density is obtained. Absent.

[0015]

EFFECTS OF THE INVENTION According to the present invention, even a large-sized sintered body can be obtained which is uniform and has no unevenness, high density, and little unevenness in color. In particular, since it is possible to suppress the occurrence of color unevenness between the peripheral portion and the central portion of the sintered body, the yield is significantly improved as compared with the conventional products.

Claims (4)

[Claims] 1. Zinc oxide powder is calcined at 400 ° C. to 800 ° C., the calcined zinc oxide powder and indium oxide powder are mixed, and the mixed powder is press-molded 1200.
The manufacturing method of the indium oxide-zinc oxide system sintered compact target characterized by sintering at ℃ -1400 ° C. 2. The method for producing a target according to claim 1, wherein the BET surface area of the zinc oxide powder after calcination is 0.2 to 4.0 m ² / g. 3. The method for producing a target according to claim 1, wherein the rate of raising the temperature to the sintering temperature in the sintering step is 350 ° C./hour or more. 4. The composition of the sintered body is 50% by weight of indium oxide.
It is above, The manufacturing method of the target of Claims 1-3 characterized by the above-mentioned.