Thin film deposition in glow discharges fed with hexamethyl-disilazane-oxygen mixtures

Thin films deposited in glow discharges fed with hexamethyl disilazane-oxygen-argon mixtures at low substrate temperature have been studied by means of in situ x-ray photoelectron spectroscopy. The results have been compared with those obtained with tetraethoxysilane-oxygen plasmas. It has been found that hexamethyldisilazane, even if less oxidable, is strongly fragmented in the plasma phase. The oxygen atoms produced by plasma dissociation promote decrease of nitrogen, carbon and hydrogen content of the film but are not able to form oxygenated nitrogen compounds. The results are in agreement with a deposition mechanism composed of different gas-gas and gas-surface reactions as previously found for tetraethoxysilane. The main difference is that in the present work the homogeneous activation reaction of unreacted compound by means of oxygen atoms is important even when the oxygen content of the feed is low. When the oxygen content of the film is high, the chemical composition of the film surface is slightly different from that of the bulk.