Patent ID: 7723204

Claim:
A method for constructing a microelectronic assembly comprising: forming a trench in a semiconductor substrate, the trench having first and second opposing inner walls and a floor and a first width; forming an insulating layer within the trench, the insulating layer having first and second portions over the first and second opposing inner walls of the trench respectively and a third portion over the floor of the trench; forming first and second conductive plates within the trench, the formation of the first and second conductive plates comprising forming a conductive layer within the trench, the conductive layer having first and second portions over the first and second opposing inner walls of the trench and the first and second portions of the insulating layer respectively and a third portion over the floor of the trench and the third portion of the insulating layer, and removing the third portion of the conductive layer to separate the first and second portions of the conductive layer and form the first and second conductive plates, wherein there is a gap between the first and second portions of the conductive layer; and forming an insulating body within the trench in the gap between the first and second portions of the conductive layer, the insulating body being adjacent to the first and second portions of the conductive layer, forming first and second semiconductor devices in the semiconductor substrate on opposing sides of the trench; and forming a second trench in the semiconductor substrate, the second trench having first and second opposing inner walls and a floor and a second width that is less than the first width.