Temperature dependence of silicon on sapphire quality

Thin (300 and 600 nm) epitaxial silicon layers were deposited on R-plane sapphire wafers by CVD technique using SiH
₄
and SiCl
₄
mixture gas diluted by hydrogen. Quality parameters of epitaxial silicon on sapphire (SOS) wafers were studied by means of XRD, AFM, UV scattering and surface PV methods. Resistivity profiles of layers were measured. Quality of SOS in dependence on initial growth (up to 80-100 nm thickness of layer) temperature and growth (up to necessary thickness) temperature was observed. Optimal temperature ranges of layer growth were experimentally estimated. Using of low growth temperature (about 945-960 °C) of initial layer growth and high growth temperature (above 960 °C) of residual layer allowed to enhance quality of SOS wafer and get uniform resistivity profile of layer. Practical application of this technique allowed to produce SOS wafers of high quality in wide optimal temperature range, increase thermal stability of SOS and process efficiency.