The Spatial Distribution of Neutral Radicals in SiH4 RF Glow Discharges Measured by a Mass Spectrometer with a Movable Gas Sampling System

A movable mass spectroscopy gas sampling apparatus has been proposed, established and equipped in a residual gas analyzer (SRS RGA-100). This mass spectroscopy analysis system has been used to measure the spatial density distributions of SiH_n (n=0-3) radicals in silane radio frequency glow discharge successfully. The experimental results demonstrate that the densities of various neutral radicals SiH_n (n=0-3) in silane plasma have each peak value near the middle position of electrodes, and the densities of SiH₂ and SiH₃ are higher than those of Si and SiH. This reveals that SiH₂ and SiH₃ may be the primary precursors in forming the a-Si:H film