Self-aligned spacers for multi-gate devices and method of fabrication thereof

Abstract

A semiconductor device includes channel members vertically stacked, a gate structure wrapping around the channel members, a gate spacer disposed on sidewalls of the gate structure, an epitaxial feature abutting the channel members, and an inner spacer layer interposing the gate structure and the epitaxial feature. In a top view of the semiconductor device, the inner spacer layer has side portions in physical contact with the gate spacer and a middle portion stacked between the side portions. In a lengthwise direction of the channel members, the middle portion of the inner spacer layer is thicker than the side portions of the inner spacer layer.