Etch characteristics of cobalt thin films using high density plasma of halogen gas

Inductively coupled plasma (ICP) reaction ion etching of Co thin films patterned with SiO2 hard marks was performed using Cl2/Ar and Cl2/O2/Ar gas mixtures. The etch rate, etch selectivity, and etch profile of the cobalt thin films were investigated by varying the gas concentration in the Cl2/Ar and Cl2/O2/Ar gas mixtures. The etching parameters, including the ICP RF power, DC-bias voltage to the substrate, and process pressure, were varied to investigate the etch characteristics. The etch mechanisms in the Cl2/Ar and Cl2/O2/Ar gas mixtures were examined using X-ray photoelectron spectroscopy, scanning probe microscopy, and optical emission spectroscopy. Finally, the cobalt thin films with 300 nm line pattern were etched using a Cl2/O2/Ar gas mixture under the optimized etch conditions.