Influence of an etch mask on the etch profile of copper thin films in propanol/Ar gas mixture

초록

Copper dry-etching without redeposition was performed using a propanol/Ar gas mixture. The etch selectivity and etch profile were evaluated by varying the concentration of propanol in the propanol/Ar gas mixture. More importantly, the effects of mask type and mask shape were investigated in terms of the etch profile. Two types of mask layers (photoresist and SiO2) with different sidewall angles were used. As the thickness of the mask layer decreased and the slant of the sidewall angle of the mask increased, the redeposition on the etched sidewalls of the copper thin films significantly decreased. In this study, copper thin films patterned using a mask with a sidewall angle of 60 degrees exhibited a redeposition-free etch profile. Optical emission spectroscopy and X-ray photoelectron spectroscopy were used to identify the main active species in the plasma and copper compounds on the etched surface, respectively. Finally, redeposition-free copper dry-etching using a propanol/Ar gas mixture was achieved under the optimized etching conditions of the mask type and mask shape.

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