Effects of SiF4 and NH3 Concentrations on the Low-Pressure CVD of Polycrystalline α-Si3N4

The effects of SiF₄ and NH₄ concentrations on the growth rate of polycrystalline α-Si₃N₄ were examined in the pressure range of 1.5 to 10.0 torr (1 torr ∽ 1.33 × 10² Pa). At low SiF₄ partial pressures, the growth rate increased almost linearly with the SiF₄ partial pressure. The relationship appeared to become zeroth-order at high SiF₄ partial pressures. Under excess NH₃ conditions, the growth rate was not significantly affected in any consistent manner by changes in the NH₃ partial pressure. A surface kinetic rate mechanism which qualitatively described the observed deposition behavior was postulated and discussed.