Process-induced SOI strain via sacrificial Ge-Si

We present here, for the first time, a method of introducing strain into Si, for example ultra-thin SOI, with a sacrificial strained Ge x Si 1-x layers. Etching proximate trenches into the Ge x Si 1-x -Si stack causes the stack to relax, transferring strain from the surface Ge x Si 1-x into the buried Si. Filling the trenches locks the strain in place, where it remains after the Ge x Si 1-x is removed. This method can be combined with more conventional stress engineering, such as strained trench fills, strained source/drain epitaxy, or strained overlayers.