Grain boundary diffusion of phosphorous in silicon

Abstract

Grain boundary diffusion of phosphorous in Wacker SILSO polycrystalline Si has been studied at temperatures between 750 and 1050 °C using a groove and stain technique. It is shown that the Fisher model of grain boundary diffusion describes the data accurately assuming an infinite source (Whipple solution) aided by Le Claire’s graphical solution of the model. The bulk DB and grain boundary D′ diffusion coefficients were best described by DB=1.6×1015 cm2/s exp(−2.09eV/kT) and D′=4.0×10−5 cm2/s exp(−1.4eV/kT), respectively, where a boundary width of 5 Å was assumed for D′. Proper procedures for reducing the data are illustrated including an important correction to penetration depth made necessary because of the inability of optical microscopy to detect very narrow diffusion regions near a grain boundary.