MOSFETs with channels on nothing and methods for forming the same

摘要

A method includes performing an epitaxy to grow a semiconductor layer, which includes a top portion over a semiconductor region. The semiconductor region is between two insulation regions that are in a substrate. The method further includes recessing the insulation regions to expose portions of sidewalls of the semiconductor region, and etching a portion of the semiconductor region, wherein the etched portion of the semiconductor region is under and contacting a bottom surface of the semiconductor layer, wherein the semiconductor layer is spaced apart from an underlying region by an air gap. A gate dielectric and a gate electrode are formed over the semiconductor layer.

主权项

1. A method comprising:
performing an epitaxy to grow a semiconductor layer, wherein the semiconductor layer comprises a top portion over a semiconductor region, and wherein the semiconductor region is between two insulation regions that are in a substrate; recessing the insulation regions to expose portions of sidewalls of the semiconductor region; etching a portion of the semiconductor region, wherein an etched portion of the semiconductor region is under and contacting a bottom surface of the semiconductor layer, wherein the semiconductor layer is spaced apart from an underlying region by an air gap; forming a gate dielectric over the semiconductor layer; and forming a gate electrode over the gate dielectric.