Semiconductor device and method of forming the same

Abstract

A method for forming a semiconductor device includes forming a fin structure extending along a first direction over a substrate, the fin structure having a height along a second direction transverse the first direction and including a stack portion of alternating channel semiconductor portions and sacrificial material portions and a hard mask portion over the stack portion. The sacrificial material portions include a first sacrificial material portion in contact with the hard mask portion and second sacrificial material portions below the first sacrificial material portion. Next, the first sacrificial material portion and the second sacrificial material portions are laterally recessed, with the first sacrificial material portion being etched to a greater extent than the second sacrificial material portions. After removing the recessed first and sacrificial material portion and sacrificial material portions to form a plurality of channel nanostructures, a gate stack is formed to surround the channel nanostructures.

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