Cu-Ga alloy sputtering target and manufacturing method thereof

Abstract

Disclosed is a Cu-Ga alloy sputtering target which enables the formation of a Cu-Ga sputtering film having excellent uniformity in film component composition (film uniformity), enables the reduction of occurrence of arcing during sputtering, has high strength, and rarely undergoes cracking during sputtering. Specifically disclosed is a Cu-Ga alloy sputtering target which comprises a Cu-based alloy containing Ga, has an average crystal particle diameter of 10 [mu]m or less, and has a porosity of 0.1% or less.

Description

technical field [0001] The present invention relates to a Cu-Ga alloy sputtering target and a manufacturing method thereof, for example, to a Cu-Ga alloy sputtering target used for forming a light absorbing layer of a CIS (CIGS) thin-film solar cell and a manufacturing method thereof. Background technique [0002] As a method for forming a light absorbing layer of a CIS (CIGS) thin-film solar cell, a Cu—Ga alloy layer and an In layer are sequentially formed and laminated by a sputtering method (for example, refer to Patent Document 1). Moreover, as a sputtering target used for formation of the said Cu-Ga alloy layer, the sputtering target whose Ga content is 10-30 atomic % is used normally, for example. [0003] As the manufacturing method of the said sputtering target, as shown in patent document 2, the method of manufacturing by melting-casting method is mentioned, for example. However, if this method is used to manufacture, since the cooling after casting is relatively s...

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Problems solved by technology

However, if this method is used to manufacture, since the cooling after casting is relatively slow, the crystal structure becomes larger, and the microscopic unevenness of the material composition occurs, which is likely to occur in the in-plane direction and the thickness direction of the sputtering target. Tendency to change composition

When a film is formed using such a sputtering target, the composition of the obtained film tends to change in the in-plane direction, and this is considered to be one of the causes of lowering the conversion efficiency of solar cells.

In addition, the sputtering target produced by the melting casting method tends to change the composition in the plate thickness direction as described above, and it is considered to be one of the causes of batch-to-batch unevenness in batch production.

[0004] In addition, pores (porosity) are prone to occur on sputtering targets manufactured by melting casting

If the porosity in the sputtering target is high, there are problems such as perforation (abnormal discharge) at the edge of the pore during sputtering, poor discharge stability in sputtering, generation of particles due to the impact of the perforation, and adhesion of particles to the substrate, etc. Decrease the adhesion between the film and the substrate, and deteriorate the performance of the solar cell, etc.

In this method, alloy powder and pure copper powder are sintered, but there is a limit to the miniaturization of the powder before sintering, and as a result, there is a limit to the miniaturization of the crystal structure

In addition, there is a limit to the uniform mixing of powders

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