The Kinetics of the Catalyzed CVD of Monocrystalline α‐Silicon Nitride Filaments

Abstract

AbstractCatalyzed chemical vapor deposition of α‐silicon nitride filaments from silicon subhydrides and ammonia was studied using calculation of nitrogen solubility in selected catalysts (silicon‐containing iron alloys), both in the solid and liquid‐state, by filament deposition experiments with catalysts of various composition and size, and by variation of the flow rates and partial pressures of precursor gases, the silicon subhydrides and ammonia. The results show that neither nitrogen solubility in, nor nitrogen diffusion through the catalyst plays a determining role in the deposition kinetics, as has been previously suggested. Instead, the deposition rate is determined by the partial dissociation of ammonia, which can be accelerated by adding diluent gases with a sufficiently high collision cross section. The catalyst material has an additional, strongly accelerating effect. The present state of research suggests that nitrogen is the preferred diluent gas and chromium an optimum alloying element.