Epitaxial Structures for Stacked Semiconductor Devices

A semiconductor structure, comprising:

• a first transistor device, comprising:
• a first plurality of nanostructures;
• a first gate dielectric layer wrapping around each nanostructure of the first plurality of nanostructures;
• a first gate electrode disposed on the first gate dielectric layer and on the first plurality of nanostructures;
• and
• a first source/drain region in contact with the first plurality of nanostructures, the first source/drain region comprising a first bottom surface and a first top surface;
• an isolation layer comprising a second bottom surface and a second top surface, wherein the second bottom surface is in contact with the first top surface;
• a seed layer comprising a third bottom surface and a third top surface, wherein the third bottom surface is in contact with the second top surface;
• and
• a second transistor device, comprising:
• a second plurality of nanostructures;
• a second gate dielectric layer;
• a second gate electrode disposed on the second gate dielectric layer and on the second plurality of nanostructures;
• and
• a second source/drain region in contact with the second plurality of nanostructures, the second source/drain region comprising a fourth bottom surface and a fourth top surface, wherein the fourth bottom surface is in contact with the third top surface.

A method, comprising:

• forming a first plurality of semiconductor layers on a substrate;
• forming a first isolation layer on the first plurality of semiconductor layers;
• forming a second plurality of semiconductor layers on the first plurality of semiconductor layers;
• removing portions of the isolation layer and portions of the first and second pluralities of semiconductor layers, wherein remaining portions of the first and second pluralities of semiconductor layers form first and second pluralities of nanostructures, respectively;
• forming a first source/drain structure in contact with the first plurality of nanostructures;
• depositing a second isolation layer on the first source/drain structures;
• depositing a seed layer on the second isolation layer;
• and
• forming a second source/drain structure using the seed layer;
• wherein the second source/drain structure is in contact with the second plurality of nanostructures.