Method of fabricating suspended microstructures

Abstract

A method of fabricating a non-perforate suspended platform on a bonded-substrate is disclosed. The method includes forming a dielectric layer on a support surface of a base substrate followed by patterning an interface surface of the dielectric layer to define a well feature. The well feature is etched until a well having a depth that leaves a thin protective layer of the dielectric layer covering the support surface. Next a platform substrate is urged into contact with the base substrate followed by annealing the base and platform substrates to fusion bond the interface surface with a mounting surface of the platform substrate. The platform substrate is thinned, using CMP for example, to form a membrane over a sealed cavity defined by the well and the mounting surface. The membrane is patterned and etch to form a plurality of trenches that extend through the membrane to the sealed cavity and define a suspended platform and a flexure. Only those portions of the suspended platform substrate necessary to define the suspended platform and the flexures are patterned and etched so that the suspended platform is devoid of perforations. As a result, the surface area of the suspended platform is maximized because perforations or the like do not subtract from the available surface area. A selective etch material such as HF is used to remove the remaining dielectric layer from beneath the platform and the flexures thereby freeing the suspended platform and the flexures. The thin protective layer prevents pitting or damage to the support surface of the base substrate during the removal of the dielectric layer.

Dependencies are inferred from the claim text.