High rate etching of 6H–SiC in SF 6-based magnetically-enhanced inductively coupled plasmas

Abstract

In this study, the etch characteristics of 6H–SiC were investigated in magnetically-enhanced SF 6 inductively-coupled-plasmas (ICP) with and without magnetic field. The etch characteristics of various metal films such as Ni, Al and Cu were also investigated to apply as the etch mask to the highly selective SiC etching process. With the magnetic field, the etch rates of SiC were increased 60% compared to those without the magnetic field. With the magnetic field, the etch rates of Ni and Al were also increased white the etch rates of Cu decreased. In fact, in the case of Cu etching using SF 6, deposition instead of etching occurred through the formation of etch products such as copper fluoride on the surface with fluorine in the plasma. Therefore, among the investigated mask materials, Cu showed infinite etch selectivity over SiC during etching using SF 6. The highest etch rate obtained for SiC was greater than 1500 nm/min at 1500 W of inductive power, −350 V of bias voltage, and 1.33 Pa of SF 6. SiC etching with the Cu mask showed highly anisotropic etch profiles.