Effect of the addition of O2 on copper etching using high density plasma of acetylacetonate/Ar

In the present study, the high density plasma etching of copper thin films masked with SiO2 was conducted using an acetylacetone/O2/Ar gas mixture. As the concentration of acetylacetone increased, the etch rates for the copper film decreased but the etch selectivity increased. The addition of O2 gas to the acetylacetone/Ar mixture greatly improved the etch profile without the redeposition on the sidewalls of the copper film. This was attributed to the formation of copper compounds containing oxygen with the assistance of a polymeric protection layer. Good etch profile for the copper film was obtained using an acetylacetone/O2/Ar gas mixture with a 4:1 vol ratio of acetylacetone to O2. The proposed acetylacetone/O2/Ar gas mixture thus represents a potential candidate gas for the dry etching of copper films.