Impurity Redistribution and Junction Formation in Silicon by Thermal Oxidation

Abstract

In the process of growing an oxide on doped silicon, electrically active impurities near the silicon/silicon dioxide interface are redistributed according to the diffusion coefficients and the distribution coefficient of the impurity between the oxide and the semiconductor. An analysis of the phenomenon predicts that single-junction or two-junction material can be obtained by oxidation of the surface of a compensated silicon crystal. For parabolic growth of the oxide, the surface concentration is independent of time, and the junction depth, gradient and sheet resistivity vary with t <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> . This has been demonstrated experimentally by oxidation of a compensated p-type silicon crystal doped with gallium and antimony.