Semiconductor structure and method of forming the same

Abstract

Semiconductor structures and methods for forming the same are provided. The semiconductor structure includes a plurality of nanostructures formed over a substrate, and an isolation structure formed over the substrate. The semiconductor structure includes a gate structure formed on the nanostructures, and the gate structure includes a gate dielectric layer and a metal layer over the gate dielectric layer. The semiconductor structure includes a first gate spacer layer formed on a sidewall of the gate structure, and a dielectric constant of the gate dielectric layer is greater than a dielectric constant of the first gate spacer layer. The gate structure includes a first portion on the isolation structure and a second portion below a topmost nanostructure, and the first portion has a first gate length, the second portion has a second gate length, and the first gate length is greater than the second gate length.

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