Patent ID: 8242578

Claim:
A circuit structure comprising: a wafer comprising: a substrate having a front side and a backside; a contact at said back side of said substrate; an electrical connector within said substrate adjacent said contact; a metal layer on said front side of said substrate adjacent said electrical connector, wherein said electrical connector is adapted to provide an electrical connection between said contact and said metal layer; and a dielectric layer on said metal layer; and a trench in said dielectric layer, wherein an entire bottom surface of said trench comprises a portion of said metal layer, wherein said contact is adapted to connect to a power supply such that a current path is established from said power supply through said back side contact, said electrical connector and said metal layer to said bottom surface of said trench, wherein said power supply is adapted to pass a current through said current path and wherein one of said electrical connector and said power supply are adapted to selectively control flow of said current through said current path.