Silicon epitaxy from silane by atmospheric-pressure chemical vapor deposition at low temperatures

Abstract

Epitaxial silicon has been grown in an ultraclean system at atmospheric pressure and low temperatures (650-750°C) using silane as a Si source in a He carrier gas. The depositions were nonselective (blanket) and demonstrate the broad capabilities of the low-temperature atmospheric-pressure growth apparatus that has previously been used for selective deposition of Si and SiGe from dichlorosilane (DCS) in H2. n-type doping using PH3 was also carried out and doping levels exceeding 1×1020/cm 3 were obtained. However, abrupt doping pulses, as have been obtained for Si growth from DCS in the same temperature regime, were not achieved. In addition, PH3 was found to diminish the growth rate and degrade the crystal quality of the layers. The films grown from silane exhibited higher levels of oxygen at the interface between the epitaxial layer and the substrate than did films grown from DCS in the same temperature range. However, high quality films, free from extended defects, as determined by transmission electron microscopy (TEM), could still be achieved.