Process for vacuum chemical epitaxy

Abstract

An injection block having a plurality of geometrically arranged injection sources for gaseous Group III metal organic compounds is oriented substantially perpendicular to the placement of at least one semiconductor wafer substrate within a vacuum reaction chamber. The injector sources are sized to provide disbursing flow of the compounds capable of depositing a layer of about 5% uniform thickness or less over substantially the entire semiconductor wafer. An injection source of Group V compounds is located centrally within the geometrically arranged injection sources for the Group III compounds. The Group V injection source is sized to supply an excess of the Group V compounds required to react with the Group III compounds in order to form Group III-V semiconductor layers on the substrate and partition the Group III sources into groups having substantially equal numbers of injection sources. An excess of Group V comounds is injected. The vacuum within the reaction chamber is adjusted at predetermined flow rates of the Group III compounds such that a mean-free path of the Group III compounds is greater than the distance from the injection source of the Group III compounds to the substrate. The substrate is heated to a temperature to which a reaction proceeds. The unreacted Group III compounds are exhausted from the vacuum chamber adjacent the edges of a substrate holder facing the top of the chamber opposite to the injection sources. In this manner, the disbursing flow of Group III compounds from the geometric arrangement of sources uniformly overlaps substantially the entire substrate and the algebraic sum of the fluxes from the Group III compound sources remains constant across the area of the substrate upon which the layer is to be deposited.