Phosphorus Doping and Sharp Profiles in Silicon and Silicon‐Germanium Epitaxy by Rapid Thermal Chemical Vapor Deposition

Abstract

In situ phosphous doping of silicon epitaxy from 700 to 1000°C by low pressure rapid thermal chemical vapor deposition in a cold wall system, using dichlorosilane as the silicon source, has been investigated. At a high phosphine flow rate, the growth rate of silicon decreases dramatically (by ∼60%) and the phosphorus incorporation level saturates. A significant persistence effect of phosphorus after turning off phosphine is observed. However, a sharper transition and higher doping level are observed in layers grown at 625°C. Improvement of the phosphous profile in silicon to ∼ 13 nm/decade is demonstrated by reactor cleaning and ex situ etching of the wafer surface during a growth interruption after phosphorus‐doped epitaxy. Despite the growth interruption, an in situ 800°C bake at 10 Torr in hydrogen before regrowth can give an oxygen‐ and carbon‐free interface without excessive dopant diffusion. © 2000 The Electrochemical Society. All rights reserved.