Quasi <i>In Situ</i> XPS on a SiO _x F _y Layer Deposited on Silicon by a Cryogenic Process

Abstract

A silicon oxyfluoride layer was deposited on a-Si samples using SiF 4 /O 2 plasma at different temperatures between −100°C and −40 °C. In situ X-ray photoelectron spectroscopy measurements were then performed to characterize the deposited layer. The sample was then brought back to room temperature and analyzed again. It has been shown that a temperature below −65 °C is needed to significantly enhance the physisorption of SiF x species. Hence, in this condition, a F-rich oxyfluoride layer, stable at low temperature only, is physisorbed. Above this threshold temperature, the native silicon oxide layer is fluorinated and the proportion of O in the deposited layer is higher and remains stable even when the sample is brought back to room temperature.