Reactive ion etching of silicon using bromine containing plasmas

Abstract

The characteristics of Si and SiO2 etching in HBr reactive ion etching plasmas have been studied by measuring etch rates, optical emission, scanning electron microscopy (SEM) cross-sectional analysis, and x-ray photoelectron spectroscopy (XPS). Etch rate measurements indicate that SiO2 is etched very slowly compared with Si, so that the Si/SiO2 etch selectivity may be as high as 400. Optical emission spectroscopy has been used to examine the gas phase species in the plasma, and emission from excited atomic bromine has been identified. The composition and thickness of reaction layers on silicon surfaces resulting from exposure to HBr plasmas has been obtained by XPS. It is found that the reaction layer on silicon due to HBr reactive ion etching is typically very thin, of the order of 1 monolayer thick. XPS has also been used to investigate the reaction layers on the sidewalls of etched trenches, and a thin oxidized layer has been detected for oxide-masked Si trench etching. © 1990, American Vacuum Society. All rights reserved.