Patent ID: 7402487

Claim:
A process for fabricating a semiconductor device comprising: a first stage comprising: providing a semiconductor substrate having a principal surface; forming a first portion of a trench in the principal surface of the semiconductor substrate using a masking pattern; covering an inner surface of the first portion of the trench with an insulating layer that is differently etchable with respect to a material of the masking pattern; and selectively removing the masking pattern with respect to the insulating layer in an etch step such that no residual portion of the masking pattern remains on the principle surface; and a second stage performed after the first stage, the second stage comprising: forming a second portion of the trench by selective epitaxial deposition of an upper layer of a semiconductor material on the principle surface of the semiconductor substrate, the layer of semiconductor material comprising a similar crystalline structure as the semiconductor substrate, wherein all surfaces of the trench are continuous within the upper layer and wherein the upper layer increases the effective depth of the trench.