SI-SIO2 INTERFACE OXIDATION-KINETICS - PHYSICAL MODEL FOR THE INFLUENCE OF HIGH SUBSTRATE DOPING LEVELS .1. THEORY

A physical model based on the statistics of silicon point defects is proposed to explain the commonly observed enhanced oxidation rates of heavily doped silicon. The physical effect of the high doping levels on the Si/SiO2 interface oxidation kinetics is postulated to be primarily electrical in nature. The high doping levels shift the position of the Fermi level toward the conduction band (n-type) or toward the valence band (p-type) even at oxidation temperatures, causing an increase in the equilibrium concentration of point defects (vacancies) in the silicon substrate. These point defects may provide reaction sites for the chemical reaction converting Si to SiO2 and thereby increase the rate at which this reaction occurs. This paper describes the theoretical basis for this model and predicts quantitatively the expected oxidation rates for n+- and p +-doped silicon under a wide range of oxidation conditions. © 1979, The Electrochemical Society, Inc. All rights reserved.