Process for fabricating submicron single crystal electromechanical structures

Claim 1

A process for fabricating, from a single crystal substrate, a high aspect ratio, released, single-crystal microstructure having any arbitrary structural orientation with respect to the substrate, comprising: providing a substrate of single-crystal material from which a microstructure is to be fabricated; depositing by plasma enhanced chemical vapor deposition of silicon nitride a first layer of a dielectric stack on a top surface of said substrate; depositing by plasma enhanced chemical vapor deposition of silicon dioxide a second layer of said dielectric stack on a top surface of said first layer; forming in said dielectric stack a pattern of the microstructure to be fabricated; transferring said pattern to said substrate by ion beam etching to form trenches having bottom walls and vertical side walls in the substrate, the trenches defining mesas having the location, shape and dimensions of the microstructure; conformally coating said substrate with a dielectric material to form a third layer on said second layer, on said trench bottom walls, and on said vertical side walls; etching back said third layer from the bottom walls of said trenches; and releasing said mesas to produce said microstructure from said substrate.