Apparatus for chemical vapor deposition using an axially symmetric gas

Abstract

In a chemical vapor deposition chamber, an improved technique for providing deposition materials to the growth surface is described. The gas carrying deposition materials is constrained to have axial symmetry thereby providing a uniform deposition of materials on the substrate. The gas can be initially directed toward the substrate with a generally uniform perpendicular velocity. The gas can be introduced into the deposition chamber through a multiplicity of apertures and is extracted from the vicinity of the substrate in a manner to preserve the axial symmetry. The apparatus permits convenient control of the deposition process by varying the distance between apparatus introducing the gas carrying the deposition materials and the substrate. The flow of gas minimizes the problems arising from autodoping of the growth layer of material. The flow of gas and generally small size of the deposition chamber minimize particulate contamination of the growing film.