JPH10273318A - Method for producing gallium oxide powder - Google Patents

Abstract

(57) [Problem] To provide a method for producing gallium oxide powder having excellent fluidity. A method for producing gallium oxide powder obtained by calcining gallium hydroxide obtained by electrolysis using gallium as an anode and, if necessary, using an aqueous solution of ammonium nitrate or ammonium chloride as an electrolytic solution, For producing gallium oxide powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing gallium oxide powder used for a high-density sintered body such as a sputtering target material used for producing a conductive thin film.

[0002]

2. Description of the Related Art Conventionally, metallic gallium is first dissolved in nitric acid and neutralized with aqueous ammonia (NH ₄ OH). Then, the deposit (gallium hydroxide) generated by the neutralization is filtered, washed, and dried. Next, a method is known in which the obtained gallium hydroxide is bi-baked to obtain gallium oxide powder.

[0003]

However, the gallium oxide powder obtained by the above-mentioned prior art has various properties (average particle size,
Variations in particle size distribution, apparent density, etc.) are relatively large. When this powder is used to produce a sintered body for a sputtering target, a high density of about 95 to 98% is obtained, but this sintered body is obtained. When a sputtering target is formed by using, the target is liable to crack under high-speed sputtering conditions, so that there is a problem that stable film formation cannot be performed.

However, in recent years, high-speed sputtering has been increasingly used, and a more stable discharge during sputtering has been developed.
It is required for the production of high-quality conductive thin films, and for that purpose, higher densities of sintered bodies used for sputtering targets and strength under high-speed sputtering conditions when using targets have been demanded. However, at the present time, the above-mentioned conventional technology cannot sufficiently cope with it.

[0005]

Means for Solving the Problems Accordingly, the present inventors have
As a result of intensive research and development to solve the above circumstances, when producing gallium hydroxide, a pre-firing substance for obtaining gallium oxide powder, the "electrolysis method" was used instead of the "neutralization method" as in the past. It has been found that the use of gallium oxide powder finally obtained improves various properties and makes it possible to produce a high-density, high-strength sintered body for a sputtering target.

The present invention has been made based on the above findings. (1) A gallium hydroxide powder obtained by calcining gallium hydroxide obtained by electrolysis with gallium as an anode is used. The method is characterized by (2) a method for producing gallium oxide powder according to (1), wherein gallium is electrolyzed using an aqueous solution of ammonium nitrate or ammonium chloride as an electrolytic solution.

[0007] The gallium oxide powder obtained according to the present invention is a powder composed of agglomerated secondary particles of fine primary particles, the secondary particles having a relatively narrow particle size. Within the distribution. Since the powder is excellent in fluidity, the density of a compact formed using the powder is high, the sintered body after firing has a high density, and the mechanical strength is high. The sputtering target obtained by using No. does not show a phenomenon such as cracking even under high-speed sputtering conditions, and can form a high-quality conductive thin film.

[0008]

Embodiments of the present invention will be described below. In an electrolytic cell having a cooling system, for example, using an aqueous solution of ammonium nitrate or ammonium chloride as an electrolytic solution, a concentration of 0.5 to 3 mol / L, and a bath temperature of 30 ° C. or less, a current density of 0.5 g / min. Was controlled within the range of 300 to 70 OA / m ² . The deposit at the bottom of the electrolytic cell was filtered, washed and dried to obtain gallium hydroxide. Next, this is 500 ~
By baking at 900 ° C., a desired gallium oxide powder can be obtained.

[0009]

EXAMPLES Examples of the present invention will be specifically described below. [Example 1] In an electrolytic cell having a cooling system, an aqueous solution of ammonium nitrate was used as an electrolytic solution, and its concentration was 1.5 m.
o1 / L, and the bath temperature was kept at 25 ° C., and electrolysis was carried out while controlling the current density to 600 A / m ² using metal gallium as an anode. Filtering, washing and drying the sediment at the bottom of the cell,
Gallium hydroxide was obtained. Next, this was bi-baked at 600 ° C. to obtain gallium oxide powder. When the obtained gallium oxide powder was observed with an electron microscope, the individual powder of the gallium oxide of the present invention was found to have a length of about 2 to 2.5 μm and a width of about 1.2 μm as shown in FIG. It was found that the secondary particles had a rectangular shape and rounded corners, and the inside thereof was composed of aggregates of fine primary particles. The secondary particles were relatively non-sized powder non-particles. Further, when the particle size distribution was measured by a (microtrack) laser diffraction method, the distribution was considerably narrow (see FIG. 3).

[Example 2] In an electrolytic cell having a cooling system, an ammonium chloride aqueous solution was used as an electrolytic solution, the concentration was 2 mol / L, the bath temperature was maintained at 25 ° C, and the current density was measured using metallic gallium as an anode. Was controlled to 700 A / m ² for electrolysis. The deposit at the bottom of the electrolytic casket was filtered, washed and dried to obtain gallium hydroxide. Next, this is 600 ° C
To obtain gallium oxide powder. When the obtained gallium oxide powder was observed with an electron microscope, Example 1 was observed.
The powder particles were similar to the above. Also (micro track)
When the particle size distribution was measured by the laser method, a fairly narrow distribution was shown as in Example 1.

Comparative Example For comparison, metal gallium was dissolved in nitric acid as a conventional method to obtain a gallium nitrate aqueous solution having a concentration of 2 mol / L, which was then removed from aqueous ammonia (NH ₄ OH).
And neutralized deposits (gallium hydroxide)
Was filtered, washed and dried. The obtained gallium hydroxide was bi-baked at 600 ° C. to obtain gallium oxide powder. When the obtained gallium oxide powder was observed with an electron microscope, as shown in FIG. 2, it was an agglomerated and dispersed powder of fine powder having a diameter of about 1 μm or less. Further, when the particle size distribution was measured by a (microtrack) laser method, a distribution in a considerably wide range was shown (see FIG. 4).

Each of the gallium oxide powders obtained in Examples 1 and 2 and Comparative Example was used, and the pressure was 5 ton / c.
These were press-formed at m ² and fired at 1500 ° C. for 7 hours in air, respectively, to obtain a sintered body of φ: 20 cm. The density of the obtained sintered body was 5.6 g / cm ³ (true density: 5.
88 g / cm ³ ). Each of these was brazed to a base metal to produce a sputtering target. Using the obtained sintered body as a target, a film was formed by a DC magnetron sputtering method. As a result, a nodule serving as a cause of a short circuit was not generated, and a stable conductive thin film was obtained for a long time. Further, when the sheet resistance and the light-transmitting properties of the obtained transparent conductive film were examined, it was confirmed that the transparent conductive film could be sufficiently heated even for a conductive thin film and showed satisfactory results. In any of the cases using the gallium oxide powder of the present invention obtained in Example 1.2, no cracking was observed and a desired film was formed, but the gallium oxide obtained by the conventional method of the comparative example was obtained. In the case of using the powder, cracking was observed and a desired film could not be formed.

[0013]

As described above, the gallium oxide powder obtained by the present invention can form a sintered body with high density and high strength, and therefore can be used as a sintered body for a sputtering target. In this case, nodules are less generated, excellent performance is exhibited under high-speed sputtering conditions, and a more stable film can be formed than the conventional method, which contributes to related fields.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of the gallium oxide powder of the present invention.

FIG. 2 is an electron micrograph of gallium oxide powder according to a conventional method.

FIG. 3 shows the results of the particle size distribution of the gallium oxide powder of the present invention by the microtrack method.

FIG. 4 shows a particle size distribution result of a gallium oxide powder obtained by a conventional method using a microtrack method.

Claims (2)

[Claims] 1. A method for producing gallium oxide powder, comprising calcining gallium hydroxide obtained by electrolysis using gallium as an anode. 2. The method for producing gallium oxide powder according to claim 1, wherein gallium is electrolyzed using an aqueous solution of ammonium nitrate or ammonium chloride as an electrolytic solution.