Characteristics of semi-aqueous cleaning solution with carboxylic acid for the removal of copper oxides residues

초록

In this study, semi-aqueous solutions containing carboxylic acids such as oxalic acid (OA), lactic acid (LA) and citric acid (CA) were formulated for the removal of copper etching residues produced at the interconnection process, and their characteristics were analyzed. Carboxylic acids in the solutions were apt to form various copper complexes according to the value of pH. Semi-aqueous solution containing 10 wt% CA showed the lowest etching rate of copper in the range from pH2 to pH7 and the highest selectivity in the range of pH 2 to pH 4. However, the cleaning solution containing 10 wt% LA revealed the superior selectivity at the range from pH 5 to pH 7. Appropriate selection of carboxylic acid should be required to improve the performance of cleaning solution. In the case of CA, the etching selectivity of copper oxide complex to copper was increased with the concentration of CA in the solution, when the solutions contain over 5 wt% CA, the copper interconnection layer has a metallic copper surface more than 88% in the area. The result shows that CA contained semi-aqueous solution has a relatively good cleaning ability.

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