FinFETs with strained well regions

摘要

A device includes a substrate and insulation regions over a portion of the substrate. A first semiconductor region is between the insulation regions and having a first conduction band. A second semiconductor region is over and adjoining the first semiconductor region, wherein the second semiconductor region includes an upper portion higher than top surfaces of the insulation regions to form a semiconductor fin. The semiconductor fin has a tensile strain and has a second conduction band lower than the first conduction band. A third semiconductor region is over and adjoining a top surface and sidewalls of the semiconductor fin, wherein the third semiconductor region has a third conduction band higher than the second conduction band.

主权项

1. A method comprising:
recessing a portion of a substrate between two insulation regions to form a recess; performing a first epitaxy to grow a first semiconductor region in the recess, wherein the first semiconductor region is relaxed; performing a second epitaxy to grow a second semiconductor region in the recess, wherein the second semiconductor region is over and contacting the first semiconductor region; performing a planarization to level top surfaces of the second semiconductor region and the insulation regions; recessing the insulation regions, wherein a top portion of the second semiconductor region over the insulation regions forms a semiconductor fin; and performing a third epitaxy to grow a third semiconductor region on a top surface and sidewalls of the semiconductor fin, wherein the second semiconductor region has a conduction band lower than conduction bands of the first and the third semiconductor regions.