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 structure comprising:
a semiconductor region over a substrate; a semiconductor layer over the semiconductor region, the semiconductor layer comprising:
a narrow portion; andtwo wide portions wider than the narrow portion connected to opposite ends of the narrow portion; an air gap underlying the narrow portion of the semiconductor layer, the semiconductor layer being supported by portions of the semiconductor region underlying the two wide portions of the semiconductor layer; a gate dielectric on a top surface and sidewalls of the narrow portion of the semiconductor layer; and a gate electrode over the gate dielectric.