Impurity Enhanced Diffusions in Silicon

Abstract

During the work on planar diffusions using liquid sources, enhanced impurity penetrations were observed in several runs. These enhanced diffusions were observed to be dependent on the amount of the impurity species fed into the diffusion zone. The experimental results have been analysed and effective diffusion coefficients have been determined at certain temperature, both for boron as well as phosphorus in silicon. The results indicate that enhanced diffusions can take place only when the impurity surface concentration is very much in excess of the intrinsic carrier concentration at the diffusion temperature.

Experience has shown that controlled enhanced diffusions could be profitably employed in the fabrication of semiconductor devices as it helps in cutting down the duration of the diffusion operation, thus saving experimental time as well as operational costs.