Patent ID: 8598675

Claim:
A device comprising: a semiconductor substrate; and a trench in the semiconductor substrate that includes: a first portion extending from a surface of the semiconductor substrate to a first depth in the semiconductor substrate, wherein the first portion has a width that tapers from a first width at the surface of the semiconductor substrate to a second width at the first depth, the first width being greater than the second width, a second portion extending from the first depth to a second depth in the semiconductor substrate, wherein the second portion has substantially the second width from the first depth to the second depth, and a third portion extending from the second depth to a third depth in the semiconductor substrate, wherein the third portion includes a first substantially linear sidewall and a second substantially linear sidewall, wherein the first substantially linear sidewall has a first length and the second substantially linear sidewall has a second length, wherein the first and second length extend from the second depth to the third depth, wherein the first substantially linear sidewall and the second substantially linear sidewalls physically contact at the third depth, and wherein the first length is transverse to a top surface of the semiconductor substrate and the second length is transverse to the top surface of the semiconductor substrate.