Patent ID: 8129245

Claim:
A method of manufacturing a semiconductor device comprising: forming an epitaxial layer over a substrate; forming a dielectric layer over the epitaxial layer and patterning the dielectric layer; etching the patterned dielectric layer to form an active trench in the portions of the dielectric layer that have been patterned to not have dielectric layer; forming a first oxide layer across a top surface of the substrate including the active trench; forming a first conductive layer on top of the first oxide layer; etching the first conductive layer away inside the active trench forming a second oxide layer over the first conductive layer; forming a second conductive layer on top of the second oxide layer, wherein the second conductive layer does not extend completely over the first conductive layer in a first edge region outside of the active trench; forming a third oxide layer over the second conductive layer; etching a first opening through the third oxide layer to expose the second conductive layer outside of the active trench; etching a second opening through the second oxide layer outside of the active trench to expose the first conductive layer but not the second conductive layer; the first opening and the second opening located in the first edge region and filling the first opening and the second opening with a conductive material.