Dislocation-Induced Deviation of Phosphorus-Diffusion Profiles in Silicon

Abstract

Deviation of phosphorus-impurity profiles in silicon from ideal ones under the diffusion condition of high surface concentrations is well known. Diffusion of high concentrations of phosphorus is also known to cause generation of dislocations with edge character in silicon wafer surfaces. A major cause of the deviation of the phosphorus profile is shown to be solute accumulation at these dislocations. The dislocation-precipitated profile is calculated for the ideal complementary error-function diffusion profile of phosphorus with 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sup> atoms/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> of surface concentration, using Ham's model of stress-assisted precipitation on dislocations. The results are shown to account for most of the major features of the experimental diffusion profiles.