Effect of Selected Ionic Inorganic Surface Contaminants on Thermal Oxidation of p-Type Polished Silicon Wafers

Abstract

The influence of substrate surface contamination, by selected inorganic ions, on the growth rate of thermal oxide on boron-doped single-crystal silicon wafers in dry oxygen at elevated temperatures is described. Of the contaminating species evaluated, only alkali metal cations and inorganic anions had any influence. Transition metal cations, common contaminants monitored in the manufacture of semiconductor devices from silicon wafers, had no affect on oxide growth rate. Increases in oxide growth rate, up to approximately twice that observed on an uncontaminated reference wafer, were noted for both alkali metal cations and inorganic anions. None of the contaminating species reduced the oxide growth rate. The dependence of oxide growth rate upon surface concentration was observed to be linear for inorganic anions and parabolic for alkali metal cations. The presence of extrinsic gettering on the wafer back surface was found to suppress, to a limited extent, the effect of contamination by only at higher surface concentrations. © 2003 The Electrochemical Society. All rights reserved.