US Patent 11749678 Semiconductor device

A semiconductor device includes a substrate with an active region being provided with a channel pattern, a device isolation layer including a first part defining the active region and a second part surrounding a first portion of the channel pattern, an upper epitaxial pattern disposed on an upper surface of the channel pattern, a gate electrode surrounding a second portion of the channel pattern and extending in a first direction, a gate spacer on the gate electrode, an interlayer dielectric layer on the gate spacer, and an air gap between a bottom surface of the gate electrode and the second part of the device isolation layer. At least a portion of the air gap vertically overlaps the gate electrode. The second portion of the channel pattern is higher than the first portion of the channel pattern.