Highly Selective and Highly Anisotropic SiO₂ Etching in Pulse-Time Modulated Electron Cyclotron Resonance Plasma

Abstract

A 10–100 µ s modulated electron cyclotron resonance (ECR) plasma is discharged to control the generation of reactive species in high-density, low-pressure plasma. The density ratio of CF 2 radicals to F atoms in the CHF 3 plasma correlates well with the pulse duration. This is because the generation of reactive species in the ECR plasma depends on time (10–100 µ s). Moreover, we found that a collimated ion flux was generated in the pulsed plasma. This method achieves a high ratio of SiO 2 etching selectivity to Si etching and eliminates microloading effects during SiO 2 contact hole etching.