Oxidation‐Induced Point Defects in Silicon

Abstract

Oxidation is among the device fabrication processes that lead to perturbation of the equilibrium point defect concentration in silicon. Both oxidation‐enhanced and reduced diffusivity (OED and ORD) of substitutional dopants is observed as well as growth and shrinkage of oxidation stacking faults (OSF). However, at present there is no general agreement as to the type of the dominant point defect at high temperature in silicon. In this paper the theory of growth and shrinkage of OSF is reviewed and it is shown that the growth is reaction rate controlled. Recent works on OED, ORD, and OSF are surveyed and used to show conclusively that two diffusion mechanisms, most likely vacancy and interstitialcy, control diffusion of substitutional atoms in silicon. It is also shown that the normalized average enhancement of interstitials during oxidation can be calculated from existing OSF data and bounds for the fractional interstitialcy diffusion mechanism and normalized average vacancy reduction are presented. Finally, physical mechanisms that can yield the observed nonlinear relationship of point defect concentration increase enhancement to oxidation rate are briefly discussed.