Semiconductor device

A semiconductor device includes a vertical stack of channel members disposed over a substrate; a gate structure covering a periphery of each channel member of the vertical stack of channel members; and a source/drain feature disposed over the substrate and coupled to the vertical stack of channel members. The source/drain feature is separated from the sidewalls of the gate structure by a first air gap from the first gate dielectric layer, and the first air gap extends into the source/drain feature. 一种半导体装置，包括通道构件的垂直堆叠物，置于基底的上方；栅极结构，包覆通道构件的垂直堆叠物的每个通道构件的周围；以及源极/漏极部件，置于基底的上方并耦接于通道构件的垂直堆叠物。源极/漏极部件是通过第一空气间隙与第一栅极介电层而与栅极结构的侧壁隔开，而第一空气间隙延伸至源极/漏极部件中。