Selection of Impurities

Abstract

Various impurities are used in VLSI processes. The key factors for the selection of the impurities are their solid solubility and diffusion coefficient. B, As, P are commonly used as doping impurities due to their high solid solubility. In and Sb are sometimes used to realize shallow junctions due to their low diffusion coefficients. We briefly showwhere various impurities are used in two distinguished devices of bipolar transistors and MOS FET’s.

Keywords: Solid solubility, diffusioncoefficient, boron, arsenic, phosphorous, antimony, indium, bipolar, MOS, emitter, base, collector, source, drain, gate, extension, pocket.