Mass spectrometry investigation of N 2O dissociation and H 2 and H 2O production during SiO 2 deposition in a remote reactor

Abstract

The composition of the gas phase during remote plasma-enhanced chemical vapour deposition (RPECVD) of SiO 2 from a diluted SiH 4N 2OHe mixture was investigated by mass spectroscopy. We chose the gas flow rates such that no direct excitation of SiH 4 by the plasma took place. Considering the observed consumption of SiH 4 and O 2, together with a comparison between the experimental and calculated N 2O dissociation, we confirmed the idea that excited molecular oxygen is mainly responsible for the deposition rate. The generation of H 2 and H 2O at different r.f. powers may indicate the existence of two qualitatively different reaction pathways. At low N 2O dissociation (low r.f. powers), no H 2O production was detected. This result will be applicable for optimization of the low temperature deposition of SiO 2.