Fabrication of thick insulating membrane embedded in Si substrate

The present paper is devoted to the description of a fabrication process of thick (tens of micrometers) insulating SiO₂ membrane embedded in a c-Si substrate. The membrane processing consists of total thermal oxidation of trenches, which were preliminary etched on front side of the substrate, conformal deposition of dielectric layer for SiO₂ trenches closing and selective etching of c-Si from back side of the substrate. The proposed process provides high accuracy of membrane thickness control and can be used in monolithic integration of dielectric based passive components with active semiconductor elements. Measurement results demonstrate that thermal insulation similar to that of glass substrate can be reached.