A new dielectric isolation method using porous silicon

Abstract

A new dielectric isolation technology is proposed. In the new structure, single crystalline Si islands are separated from the silicon substrate by oxidized porous silicon. It is based on the following characteristics of the porous silicon oxide formation: (1) p-type Si is more easily changed to porous silicon than n-type Si; (2) porous silicon is formed along the anodic reaction current flow line; (3) the change in volume of porous silicon after oxidation is relatively small; (4) thick porous silicon films (10 μm) can be obtained easily. In this method, a p-type isolated layer is obtained by proton implantation used for an n-type layer formation. Lateral p- n junctions fabricated in such isolated silicon layers show lower leakage current than those reported in SOS technology.