Infrared spectroscopic analysis of plasma-treated Si(100)-surfaces

Infrared reflection spectroscopy (specular reflection, attenuated total ref lection) has been applied in combination with spectroscopic ellipsometry an d electron microscopy to analyze the surface structure of plasma-treated Si (100) surfaces. It is shown that plasma treatments in oxygen and fluorine o r chlorine-containing gases cause the formation of a thin surface layer hav ing thicknesses of a few nanometers. The layer was identified to consist of SiO2 for treatments in an oxygen plasma. Analyses of layers formed by trea tments in a fluorine-containing plasma do not confirm the generally assumed model. Different Si-F vibration modes were identified in the surface layer caused by a SF6 plasma. They correlate, however, with SiF and SiF2 molecul es. There are no indications of the existence of the generally assumed SiF4 . Neither has SiOF2 been proven in layers produced by etching in a SF6/O-2 plasma.