SiO2 Etching Characteristics with Low-Energy Ions Generated by Electron Cyclotron Resonance Plasma Using CF4 and NF3 Gases

Abstract

We report on the basic investigations of SiO2 etching characteristics in low ion energy regions using electron cyclotron resonance (ECR) plasma. The SiO2 etch rate is enhanced by higher microwave power and higher pressure, but it is not dependent solely on the ion current density. In the case of NF3 plasma, the ion sheath potential depends only on pressure, and the ion current density shows a strong dependence on the distance between the ECR region and the wafer. The yield of SiO2 etched with NF3 plasma increases as the distance increases. The etching yield of SiO2 strongly depends on the ion energy and the flux ratio of neutrals to ions.