Field effect transistors having concave drain extension region and method of making the same

Abstract

A field effect transistor includes a source region embedded in a semiconductor material layer, a drain region embedded in the semiconductor material layer and laterally spaced from the source region by a channel, a gate stack including a gate dielectric and a gate electrode, a shallow trench isolation portion embedded in an upper portion of the semiconductor material layer and contacting the drain region and the gate stack, and a concave drain extension region continuously extending underneath the shallow trench isolation portion from a bottom surface of the gate dielectric to a bottom surface of the drain region.