Etch characteristics of copper thin films in high density plasma of CH4/O2/Ar gas mixture

Abstract

Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO2 masks was performed using CH4/O2/Ar gas mixture. The etch characteristics of copper films in CH4/Ar and O2/Ar gases were examined to determine the roles of CH4 and O2, respectively. The etch rates and etch profiles of copper films were investigated by varying the O2 concentration in CH4/O2/Ar gas mixture. In the optimized CH4/O2/Ar gas mixture, systematic etching of copper films was performed by changing the etch parameters, including ICP RF power, DC-bias voltage, and process pressure. As the ICP RF power and DC-bias voltage was increased and the process pressure was decreased, the etch rate increased and the etch profile improved. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy were used to determine the etch mechanism in the CH4/O2/Ar gas mixture. Finally, the etching of copper films in the optimized CH4/O2/Ar gas mixture was successfully achieved with good etch profile with a high degree of anisotropy.