Comparative study of CF4 + O2 and C6F12O + O2 plasmas for reactive-ion etching applications

This work represents a comparative study of gas-phase parameters and reactive-ion etching kinetics for Si and Si and SiO2 in CF4 + O-2 and C6F12O + O-2 plasmas. An interest to the C6F12O gas is because it combines the low global warming potential (low environmental impact) and weakly studied dry etching performance. It was shown that the investigated gas systems showed similar effects of processing conditions on electron- and ion-related plasma parameters as well as on the densities of F and O atoms. Etching experiments showed identical behaviors of Si and SiO2 etching rates as well as very similar SiO2/Si etching selectivities. The notable feature of the C6F12O + O-2 plasma is only the systematically lower absolute etching rates that correlate with lower in F atom densities.