Patent ID: 6987052

Claim:
A method of forming a semiconductor structure in a semiconductor wafer, the method comprising the steps of: forming an epitaxial layer on a least a portion of a semiconductor substrate of a first conductivity type; forming at least one trench through the epitaxial layer to at least partially expose the substrate; doping at least one or more sidewalls of the at least one trench with an impurity of a known concentration level so as to form a low-resistance electrical path between an upper surface of the epitaxial layer and the substrate; and substantially filling the at least one trench with a filler material; wherein the step of doping at least one or more sidewalls of the at least one trench with an impurity comprises: cleaning the sidewalls of the at least one trench to substantially remove any organic material in the at least one trench; predepositing the impurity on at least one or more sidewalls of the at least one trench; and driving in the impurity.