Patent ID: 7855415

Claim:
A semiconductor device comprising: a drift region of a first conductivity type; a well region extending above the drift region and having a second conductivity type opposite the first conductivity type; an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer forming an upper electrode and a second conductive layer forming a lower electrode, the upper electrode being disposed above the lower electrode and separated therefrom by inter-electrode dielectric material; source regions having the first conductivity type formed in the well region adjacent the active trench; a first termination trench extending below the well region and disposed at an outer edge of an active region of the device; wherein the first termination trench is lined with a layer of dielectric material that is thicker than the dielectric material lining the sidewalls of the active trench, and the termination trench comprises a conductive material; and wherein the conductive material inside the first termination trench is buried under dielectric material in a lower portion of the termination trench.