Soft X-ray stimulated etching reaction in the SF 6/SiO 2 adsorption system studied by neutral products detection

Abstract

Soft X-ray stimulated etching reactions in the adsorption systems SF 6/a-SiO 2 and SF 6/poly-Si at low temperature (≈ 100 K) have been studied by the direct detection of neutral products using a quadrupole mass spectrometer (QMS) in the 90–190 eV excitation energy range. The neutral products could be detected in a-SiO 2, but not in poly-Si. This is evidence that there is a high material selectivity. The yield curve of the SiF + fragments which arised from SiF x neutral products in the SF 6/SiO 2 and the absorption spectrum of SF 6/poly-Si were measured. The peak positions of both spectra are similar. This suggests that the layers containing SiF x were intially produced on both surfaces. The difference in reactivities between SiO 2 and poly-Si can be ascribed to the desorption process of etching products from the reaction layers.