Semiconductor device

Abstract

A semiconductor device includes an active region extending on a substrate in a first direction, a plurality of channel layers on the active region to be spaced apart from each other in a vertical direction, perpendicular to an upper surface of the substrate, the plurality of channel layers including silicon germanium, a gate structure intersecting the active region and the plurality of channel layers on the substrate to surround the plurality of channel layers, respectively, a source/drain region on the active region on at least one side of the gate structure, the source/drain region in contact with the plurality of channel layers, and a substrate insulating layer disposed between the source/drain region and the substrate. The source/drain region includes a first layer in contact with a side surface of the gate structure, side surfaces of the plurality of channel layers, and an upper surface of the substrate insulating layer.