Patent attributes
A method for forming a semiconductor structure is provided. The method includes forming first and second fin structures, wherein each of the first and the second fin structurez include first semiconductor layers and second semiconductor layers alternatingly stacked, and forming a first mask structure to cover the second fin structure. The first mask structure includes a first dielectric layer and a second dielectric layer over the first mask structure, and the first dielectric layer and the second dielectric layer are made of different materials. The method also includes forming a first source/drain feature in the first fin structure, removing the first mask structure, forming a second source/drain feature in the second fin structure, removing the first semiconductor layers of the first fin structure and the second fin structure, thereby forming first nanostructures and second nanostructures, and forming a gate stack around the first and second nanostructures.