Impurity Redistribution during Silicon Epitaxial Growth and Semiconductor Device Processing

Abstract

A model has been developed that can account for both front and back “autodoping” effects during epitaxial growth as well as impurity redistribution during further high‐temperature processing. The model incorporates three dopant fluxes, i.e., (i) the flux from the solid into the gas phase at the rear of the wafer, (ii) the flux from the solid to the front surface of the wafer, and (iii) the flux from the bulk gas phase into the boundary layer near the front surface of the wafer in which transport of dopant occurs by diffusion only. The redistribution of impurities both within the solid semiconductor and in the gas phase are investigated from a theoretical viewpoint. Numerical solutions are obtained using the Crank‐Nicolson method. Implications of differences between this approach and previous work are discussed. Calculated results are presented to illustrate the variety of problems that may be solved using this mathematical approach.