Effect of H2 dilution in the catalytic CVD processes of SiH4/NH3 system

Catalytic chemical vapor deposition (Cat-CVD) is one of the most promising techniques for preparing thin SiN_x films at low substrate temperatures by using SiH₄ and NH₃ as material gases (Matsumura et al., 2001 and Osono et al., 2003). One of the problems in this technique has been the low decomposition efficiency of NH₃ in the presence of SiH₄. The decomposition efficiency decreases sharply by the introduction of a small amount of SiH₄ (Umemoto, 2003). Recently, it has been found that the addition of H₂ improves not only the decomposition efficiency of NH₃ in the presence of SiH₄ but also the SiN_x film quality (Mahan et al., 2003 and Wang et al., 2004). In the present work, the catalytic decomposition efficiency of NH₃ in the SiH₄/NH₃/H₂ system is determined. The absolute H-atom densities were also measured under several conditions.