US Patent 11062937 Dielectric isolation for nanosheet devices

A technique relates to a semiconductor device. A stack is formed over a bottom sacrificial layer, and the bottom sacrificial layer is on a substrate. The bottom sacrificial layer is removed so as to create an opening under the stack, and a dummy gate anchors the stack. A support structure is formed in the opening, and the support structure includes an air gap and is positioned between the stack and the substrate. One or more layers are formed on the support structure. Source or drain regions are formed over the one or more layers, such that the source or drain regions are isolated from the substrate.