Semiconductor device with backside gate isolation structure and method for forming the same

Abstract

A semiconductor device includes a first dielectric layer, a stack of semiconductor layers disposed over the first dielectric layer, a gate structure wrapping around each of the semiconductor layers and extending lengthwise along a direction, and a dielectric fin structure and an isolation structure disposed on opposite sides of the stack of semiconductor layers and embedded in the gate structure. The dielectric fin structure has a first width along the direction smaller than a second width of the isolation structure along the direction. The isolation structure includes a second dielectric layer extending through the gate structure and the first dielectric layer, and a third dielectric layer extending through the first dielectric layer and disposed on a bottom surface of the gate structure and a sidewall of the first dielectric layer.