Nanostructure field-effect transistor device and method of forming

A semiconductor device comprising:

• a substrate;
• a fin protruding above the substrate;
• a first source/drain region and a second source/drain region that are disposed over the fin;
• channel layers over the fin and between the first source/drain region and the second source/drain region;
• a gate structure over the fin and around the channel layers;
• and
• an air gap between the first source/drain region and an upper surface of the fin distal from the substrate.

A semiconductor device comprising:

• a substrate;
• a fin protruding above the substrate;
• first channel layers over the fin;
• a first gate structure over the fin and around the first channel layers;
• second channel layers over the fin;
• a second gate structure over the fin and around the second channel layers;
• a source/drain region over the fin between the first gate structure and the second gate structure, wherein the source/drain region is connected to the first channel layers and the second channel layers;
• inner spacers disposed laterally between the source/drain region and the first gate structure, and between the source/drain region and the second gate structure;
• a dielectric material extending along a first upper surface of the fin distal from the substrate;
• and
• an air gap between the source/drain region and the dielectric material.