Channel regions in stacked transistors and methods of forming the same

Abstract

A method includes: epitaxially growing a first multi-layer stack over a first substrate; epitaxially growing a second multi-layer stack over a second substrate; and bonding the first multi-layer stack to the second multi-layer stack. The first substrate and the second substrate have different crystalline orientations. The method further includes patterning the first multi-layer stack and the second multi-layer stack to form a fin, the fin comprising a plurality of lower nanostructures alternatingly stacked with first dummy nanostructures and a plurality of upper nanostructures alternatingly stacked with second dummy nanostructure; replacing the first dummy nanostructures with a first gate stack, the first gate stack surrounding each of the plurality of lower nanostructures; and replacing the second dummy nanostructures with a second gate stack, the second gate stack surrounding each of the plurality of upper nanostructures.