Abstract: The starting material for this process is a bonded silicon wafer with the appropriate thickness of separating silicon oxide and the appropriate thickness of superficial silicon. The thicknesses are chosen to give the desired operating characteristics of the device. First a masking oxide is formed and holes are opened in the masking oxide having the diameter needed for the pedestal. The holes are then opened down to the separating silicon oxide. If KOH is used then the etch will stop at the oxide automatically. After the silicon etch the oxide is opened to the silicon substrate.

Abstract: The present invention provides a method of treating a SIMOX wafer so that oxygen precipitates and heavy metal, carbon, and other contaminants are substantially reduced. The method includes forming a protective layer on the SIMOX surface, heating the wafer and protective layer so that the precipitates and contaminants disolve and diffuse into the protective layer, and slowly cooling the wafer to permit continued diffusion during cooling.

Abstract: Heavily doped substrates of silicon wafers are inhibited from contaminating by autodoping phenomenon lightly doped epitaxial growing films by providing a thick film of silicon on the susceptor for CVD processing in an RF powered reactor. The susceptor film of silicon serves to provide a silicon seal to the rear surface of the substrate to prevent or at least inhibit outdiffusion of dopants that can contaminate the epitaxial film. For example, substrates heavily doped with arsenic, phosphorus or boron at concentrations of 10.sup.19 atoms/cc are inhibited from autodoping contaminating epitaxial films of silicon lightly doped with the same dopant at 10.sup.14 atoms/cc.

Abstract: A variable sweep means connects the rotating shaft of an electric motor to a rotatable gas manifold in a rotary disc reactor to convert rotation of the shaft into reciprocating oscillation of the gas manifold. A cycle timing control means for varying electric motor speed at two independent speeds is connected to the electric motor. The control means varies the oscillation speed of the gas manifold at two sweep rates by varying electric motor speed automatically during each sweep cycle.