Patent ID: 8716075

Claim:
A method of forming a floating body field-effect transistor, comprising: forming a semiconductor first Si x Ge (1-x) -comprising layer over an insulator; forming a semiconductor second Si x Ge (1-x) -comprising layer over the semiconductor first Si x Ge (1-x) -comprising layer, the second Si x Ge (1-x) -comprising layer having greater Ge quantity than the first Si x Ge (1-x) -comprising layer; forming a semiconductor silicon-comprising layer over the second Si x Ge (1-x) -comprising layer, the second Si x Ge (1-x) -comprising layer having greater quantity of Ge than any quantity of Ge within the semiconductor silicon-comprising layer; forming a gate dielectric and a gate electrode over the semiconductor silicon-comprising layer; using the gate dielectric and the gate electrode at least in part as a mask, etching into unmasked portions of the semiconductor silicon-comprising layer, the second Si x Ge (1-x) -comprising layer, and the first Si x Ge (1-x) -comprising layer to form a floating body channel region comprising at least the semiconductor silicon-comprising layer and the first Si x Ge (1-x) -comprising layer; replacing at least some of the second Si x Ge (1-x) -comprising layer with insulative material; and after the replacing, epitaxially growing semiconductive silicon-comprising material from laterally outermost sidewalls of at least the silicon-comprising layer and the first Si x Ge (1-x) -comprising layer to form a pair of source/drain regions.