Effects of radio frequency bias frequency and radio frequency bias pulsing on SiO2 feature etching in inductively coupled fluorocarbon plasmas

Abstract

The effect of radio frequency (rf) bias frequency on SiO2 feature etching using inductively coupled fluorocarbon plasmas is investigated. It is found that the rf bias frequency can have an important effect on SiO2 feature etch rate, microtrenching phenomena, and SiO2-to-photoresist etch selectivity. In addition, the effect of rf bias pulsing on inductively coupled fluorocarbon plasma SiO2 etching has been studied and a model that describes the data well is presented. The model assumes that fluorocarbon deposition occurs while the rf bias is off, fluorocarbon etching occurs during the first part of time that the bias is on, and substrate etching occurs once the fluorocarbon material has been removed from the substrate.