Patent ID: 8492252

Claim:
A method comprising: patterning a photoresist layer on a structure to define an opening and expose a first planar area on a substrate layer; forming doped portions on a sacrificial substrate layer of the substrate layer to define an exposed doped portion of the sacrificial substrate layer and an exposed undoped portion of the sacrificial substrate layer; removing a portion of the photoresist to form a second opening defining a second planar area on the substrate layer; and etching to form a first cavity having a first depth defined by the first opening to expose a first contact in the structure and to form a second cavity defined by the second opening to expose a second contact in the structure, wherein the exposed doped portion is more selective to etching than the exposed undoped portion, and wherein the etching includes etching the doped portion such that the etching of the first cavity and the etching of the doped portion results in openings of different depths.