An i n s i t u infrared study on the interaction of oxygen plasmas with Si and fluorine plasmas with SiO2 surfaces

Abstract

Infrared spectroscopy has been used to study in situ the oxidation of silicon in an oxygen plasma (10 Pa) and the etching of this silicon oxide in a He:F2 (5%) plasma (50 Pa) by monitoring the Si–O stretch vibration. The sensitivity of the present system is 10% of a monolayer of oxide. A wave number shift is observed from 1088 to 1045 wave numbers during the first stage of the oxidation. The oxide-layer thickness is determined from the integrated-band intensity. This thickness increases with the square root of the oxygen plasma exposure time and decreases linearly with etch time in the fluorine plasma (6 nm/min).