US Patent 9755017 Co-integration of silicon and silicon-germanium channels for nanosheet devices

Nanosheet semiconductor devices and methods of forming the same include forming a first nanosheet stack in a first device region with layers of a first channel material and layers of a sacrificial material. A second nanosheet stack is formed in a second device region with layers of a second channel material, layers of the sacrificial material, and a liner formed around the layers of the second channel material. The sacrificial material is etched away, but the liner protects the second channel material from the etch. Gate stacks are formed over and around the layers of first and second channel material to form respective first and second semiconductor devices in the first and second device regions.