A Movable Mass Spectroscopy Sampling Apparatus for Measuring Spatial Distribution of Neutral Radicals in Silane Plasma

A movable mass spectroscopy gas sampling apparatus has been established and a straight-line fit of silane depletion fraction f is proposed. The spatial density distributions of SiH_n (n=0-3) radicals in
silane radio frequency glow discharge have been measured by a mass spectrometer. The experimental results demonstrate that the densities of the neutral radicals have the peak value near the middle position of electrodes, and the densities of SiH₂ and SiH₃ are higher than those of Si and SiH in silane plasma. This reveals that SiH₂ and SiH₃ may be the primary precursors in forming the a-Si:H film.