Semiconductor device having thin bottom channel and manufacturing method thereof

Abstract

A semiconductor device includes semiconductor nanosheets, a gate structure, and a dielectric spacer. The semiconductor nanosheets are vertically stacked over each other, disposed above a semiconductor substrate, and serve as channel regions. A bottommost semiconductor nanosheet most proximate from the semiconductor substrate is a thinnest nanosheet of the semiconductor nanosheets. The gate structure surrounds each of the semiconductor nanosheets in a first cross-section, and the dielectric spacer is interposed between the bottommost semiconductor nanosheet and the semiconductor substrate and adjoins the gate structure in the first cross-section.