SUPER HIGH RATE DEPOSITION OF HOMO- AND HETERO-EPITAXIAL SILICON THICK FILMS BY MESO-PLASMA CVD

Mesoplasma chemical vapor deposition has been demonstrated for deposition of epitaxial silicon thick films. The growth rate of the homoepitaxial films reached as fast as 60 nm/sec at temperatures around 700°C, while heteroepitaxial films on sapphire substrates were achieved at ∼ 10 nm/s at substrate temperatures ranging from 450 to 800°C. For both films, the microstructures were found to vary from agglomerated to epitaxial with an increase in the plasma power. In particular, despite the high rate, the interface between film and subsrate was observed to be atomically smooth. A simple calorimetric analysis during deposition has revealed that the boundary layer thickness between plasma and substrate reduced with increasing the power and became comparable to the mean free path of the gases when epitaxy was achieved. This potentially suggests that the formation of less agglomerated clusters / thermally activated atoms within the boundary has significant contribution to the high rate epitaxial growth. The quality of these epitaxial films was confirmed by the fact the hall mobilities reached as high as 260 cm2/V·s for homoepitaxial and 130 cm2/V·s for heteroepitaxial films, which are both comparably high in contrast to that achieved by conventional techniques.