The Thermodynamic Behavior of the Si-H System and Its Role in Si-CVD from SiH₄

Thermodynamic calculations of the Si-H system were performed at typical chemical vapor deposition conditions of total pressure, partial pressure of SiH₄, ambient, and temperature. Effects of the conditions on the equilibria of the system were examined, and homogeneous reaction mechanisms in the system were qualitatively discussed. The main conclusions include that Si deposition at low temperatures is due to SiH₄ alone and high-temperature film deposition is dominated by gaseous silane intermediates produced through homogeneous reactions of SiH₄. As the homogeneous reactions develop, homogeneous nucleation of Si₃ occurs. Both inert ambient and low pressure promote the homogeneous reactions.