Degree of Dissociation of SiH₄ under Microwave Plasma CVD

Abstract

The degree of dissociation of SiH₄ gas in the microwave plasma CVD system has been obtained.
By means of attaching a glass pipe on the gas sampling orifice, it has been shown that the fragments from SiH₄, SiH_n (n=03), can be excluded and that only SiH₄ molecules are extracted from a dissociated Ar/SiH₄ mixture gas to the mass spectrometer. The degree of dissociation of SiH₄ gas is evaluated from the ratio of the mass spectral line intensities that are measured with microwave discharges on and off. Using the glass pipes of different length, the degree of dissociation of SiH₄ gas is measured at the different points of a chamber.
The degree of dissociation of SiH₄ gas is from 40% to 70% and the radial distribution of it in the deposition chamber of this microwave plasma CVD system is very uniform.