Fine-line formation of cobalt thin films via cyclic etching using two-step process

Co thin films were etched via cyclic etching using a two-step process of Cl2 plasma and Ar sputtering. In the first step, the Co surface was chlorinated by exposing the Co film to Cl2 plasma to form a CoCl2 layer, and the chlorinated Co film was removed via Ar sputtering in the second step. The saturation point of chlorination in the first step provided a 2 nm-thick CoCl2 layer. In the second step, the dc bias voltage and Ar sputtering time were varied to optimize the removal of the CoCl2 layer. A close relationship between the thickness of the CoCl2 layer and the sputtering conditions was revealed, which was responsible for the etch profiles of the Co films. Finally, 300 nm patterns of the Co films were successfully etched via cyclic etching without redeposition on the sidewall.