Redeposition-free dry etching of copper thin films using organic gas mixtures

Dry etching of copper thin films was investigated using acetylacetone/Ar and acetone/Ar gas mixtures. The effect of gas concentration on both the etch rate and the etch profile was evaluated, and the acetone/Ar gas mixture was found to provide redeposition-free etch profile with a high etch rate. Optical emission spectroscopy shows that the intensities of the effective active species were higher in acetone/Ar than in acetylacetone/Ar. X-ray photoelectron spectroscopy confirms the formation of copper compounds (CuO_x and Cu(OH)₂) during the etching process. Optimization of the etch parameters yields a good etch profile without redeposition. These results indicate that the acetone/Ar gas mixture is a promising etch gas for achieving redeposition-free copper etching at a high etch rate.