Nanosheet structure with isolated gate

A method for forming a semiconductor structure comprising:

• providing a substrate;
• epitaxially growing an oxide layer over the substrate;
• epitaxially growing a stack of a plurality of alternating semiconductor layers over the epitaxial oxide layer;
• forming a plurality of suspended nanosheets from the epitaxially grown alternating semiconductor layers;
• forming a source/drain semiconductor region in contact with lateral portions of the plurality of suspended nanosheets and the epitaxial oxide layer, wherein forming the plurality of suspended nanosheets comprises:
• forming, by epitaxial growth, at least two stacks, each including a plurality of sacrificial release layers and at least one alternating nanosheet channel layer on the substrate;
• forming a dummy gate on a top most layer of each of the at least two stacks;
• and
• after forming the source/drain semiconductor region, removing both of i) the dummy gate on a top most layer of each of the at least two stacks and ii) the plurality of sacrificial release layers to create the plurality of suspended nanosheets, wherein the source/drain semiconductor region physically supports and is in contact with the plurality of suspended nanosheets;
• forming a plurality of functional gate structures, each of the plurality of functional gate structures in contact with at least one of the plurality of suspended nanosheets;
• and
• decoupling the i) the plurality of functional gate structures and ii) the plurality of suspended nanosheets from the substrate by contacting at least a portion of a bottom one of the plurality of functional gate structures with the epitaxial oxide layer.