Patent ID: 8384140

Claim:
A structure comprising: a shallow trench isolation (STI) structure formed in a wafer body; a first hole formed in the STI structure to a first depth, and having a cross-sectional size; a second hole aligned with the STI structure and formed into the wafer body to a second depth greater than the first depth, and having a different cross-sectional size less than the cross-sectional size; a first plate formed within the first hole and the second hole, and being isolated from the wafer body by a first insulator layer formed in the first hole and the second hole; and a second plate formed within the first hole and the second hole, and being isolated from the wafer body and the first plate by a second insulator layer formed in the first hole and the second hole, and top surfaces of the STI structure, the first plate, the first insulator layer, the second plate, and the second insulator layer being at a same level.