Effect of filament temperature and deposition time on the formation of tungsten silicide with silane

The effect of filament temperature and deposition time on the formation of tungsten silicide upon exposure to the SiH₄ gas in a hot wire chemical vapor deposition process was studied using the techniques of cross-sectional scanning electron microscopy and Auger electron spectroscopy. At a relatively low temperature of 1500 °C, the decomposition of WSi₂ phase and the diffusion of Si towards the silicide/W interface produce a thick W₅Si₃ layer. The diffusional nature leads to a parabolic rate law for silicide growth. An exponential decrease of silicide thickness with temperature between 1600 and 2000 °C illustrates the dominance of Si evaporation at higher temperatures (T ≥ 1600 °C) over the silicide formation.