Influence of initial conditions on point defect diffusion. Impact on models

The commonly used partial differential equations for point defect diffusion are reviewed. Special attention is given to the initial conditions of the point defect concentrations. Our numerical simulation clearly show that the assumption of initially equi-destributed point defect concentrations at process temperature is justified only for a very special choice of parameters. A more general treatment of the problem leads to an inhomogenous distribution of point defects and in consequence to strongly different concentrations beneath a silicondioxide and a siliconnitride layer even for heat treatment under inert conditions. (AIS-B)