Boron Autodoping during Silane Epitaxy

In order to calculate the redistribution of boron in silicon by both diffusion and autodoping during epitaxial growth, certain materials parameters must be known as a function of temperature. The parameters are the diffusion coeffi-cient of boron, the evaporation coefficient of boron from silicon, and the silicon evaporation rate in a hydrogen ambient. The value of the diffusion coefficient of boron is already well known while the values for the other two parameters have not been determined over the temperature range usually used for epi-taxial growth. The evaporation coefficient of boron in silicon in a hydro-gen ambient was experimental ly determined to be h = 1.674 • 10 T e-2.4s/kT where h is in microns per minute, the energy is expressed in electron volts, and temperature is in degrees Kelvin. The evaporation rate of silicon in a hydrogen ambient was measured as 0.013 _ _ 0.003 microns/min in a hydrogen ambient. These results were obtained in the temperature range from 1190 ~ to 1380~ These results allowed the accurate prediction of boron back surface "auto