Abstract: A semiconductor structure includes a fin extending from a substrate and oriented lengthwise in a first direction, where the fin includes a stack of semiconductor layers, an isolation feature disposed over the substrate and oriented lengthwise in a second direction perpendicular to the first direction, where the isolation feature is disposed adjacent to the fin, and a metal gate structure having a top portion disposed over the stack of semiconductor layers and a bottom portion interleaved with the stack of semiconductor layers. Furthermore, a sidewall of the bottom portion of the metal gate structure is defined by a sidewall of the isolation feature, and the top portion of the metal gate structure laterally extends over a top surface of the isolation feature.

Abstract: A method for manufacturing a semiconductor structure includes forming a fin over a substrate, wherein the fin includes first semiconductor layers and second semiconductor layers alternating stacked. The method also includes forming an isolation feature around the fin, forming a dielectric feature over the isolation feature, forming a cap layer over the fin and the dielectric feature, oxidizing the cap layer to form an oxidized cap layer, forming source/drain features passing through the cap layer and in the fin, removing the second semiconductor layers in the fin to form nanostructures, and forming a gate structure wrapping around the nanostructures.

Abstract: A semiconductor structure includes a semiconductor substrate; fin active regions protruded above the semiconductor substrate; and a gate stack disposed the fin active regions; wherein the gate stack includes a high-k dielectric material layer, and various metal layers disposed on the high-k dielectric material layer. The gate stack has an uneven profile in a sectional view with a first dimension D1 at a top surface, a second dimension D2 at a bottom surface, and a third dimension D3 at a location between the top surface and the bottom surface, and wherein each of D1 and D2 is greater than D3.