Method of making silicon on sapphire field effect transistors with specifically aligned gates

Claim 1

A process for manufacturing field effect transistors on an insulating substrate selected from the group consisting of sapphire, spinel and beryllium oxide; comprising: (a) depositing a mask comprising a layer of silicon nitride directly on an exposed surface of said insulating substrate; (b) defining an aperture in said mask to expose portions of the underlying insulating substrate; (c) exposing said mask and said exposed portions of said insulating substrate to a gas mixture comprised of sulfur hexafluoride gas and a carrier gas at a temperature less than 1050° C. for a time period sufficient to form blind holes in said insulating substrate; (d) epitaxially growing silicon in said blind holes; and (e) forming field effect transistors in said epitaxially grown silicon, the gates of said field effect transistors being aligned orthogonal to the projection of the "c" axis on the "r" plane of said insulating substrate.