Patent ID: 8796138

Claim:
A method for forming a via in a portion of a semiconductor wafer comprising a substrate, the method comprising the steps of: forming a front surface layer on a first surface of a semiconductor substrate, wherein the front surface layer comprises a first contact; forming a second contact through the semiconductor substrate in electrical contact with the first contact, wherein forming the second contact comprises: forming a trench in a second surface of the semiconductor substrate, opposite the first surface, the trench surrounding a first part of the substrate such that the first part is separated from a second part of the substrate, wherein the trench extends through the substrate from the second surface to the first surface of the semiconductor substrate; forming a hole through the substrate within the first part; forming at least one conformal metal layer to line the trench and hole; removing a portion of conformal metal layer in the trench to isolate a remaining portion of the conformal metal layer lining the hole; and filling the trench and hole with dielectric material, wherein the second contact is a via that comprises the hole and a portion of the conformal metal layer lining the hole.