Apparatus with overlapping deep trench and shallow trench and method of fabricating the same with low defect density

Abstract

A method for fabricating conductive deep trenches in conjunction with shallow trench isolations in a semiconductor device. The disclosed method introduces an integrated sequence during which a shallow trench is etched and filled before a deep trench is etched and filled. The disclosed method advantageously reduces cone defects and process complexity associated with the formation of a conductive deep trench within a shallow trench isolation structure. Fabricated under the integrated sequence, the conductive deep trench may extend through a shallow trench dielectric layer and into the substrate, where the top surfaces of both the conductive deep trench and shallow trench dielectric layer are substantially cone free.