SiO 2 Etching in C 4 F 8 /O 2 Electron Cyclotron Resonance Plasma

We report the application of C 4 F 8 /O 2 electron cyclotron resonance (ECR) plasma to SiO 2 etching. The effect on SiO 2 etching characteristics of O 2 addition to C 4 F 8 ECR plasma is investigated. In C 4 F 8 ECR plasma (no O 2 addition), strong reactive ion etching (RIE) lag effect of SiO 2 and poly-Si etching is observed. However, with O 2 addition, the RIE lag effect of SiO 2 etching decreases markedly whereas the RIE lag effect of poly-Si etching decreases gradually. Consequently, SiO 2 etching selectivity to poly-Si increases. The results of mass spectrometric measurement using two orifices indicate that surface reaction probability of fluorocarbon molecules is affected by O 2 addition.