Oxygen Incorporation during Low Temperature Chemical Vapor Deposition Growth of Epitaxial Silicon Films

We have studied the incorporation kinetics of oxygen during the chemical vapor deposition (CVD) growth of epitaxial silicon and silicon-germanium layers at temperatures between 700 and 750°C. In this temperature range, the incorporation of oxygen into the growing film is a kinetically driven process and is not governed by equilibrium conditions. Oxygen concentrations exceeding the solid solubility for interstitial oxygen in silicon can be incorporated into the epitaxial layers. We determine an effective sticking probability for oxygen on the surface of silicon under CVD growth conditions and find it to be 100 times lower than that found in ultrahigh vacuum experiments. This reduction in sticking is due to both hydrogen surface coverage and boundary layer effects. We also have determined the maximum oxygen contamination level allowed in the gas stream for the CVD growth of low oxygen content silicon films.