Gate Air Spacer for Fin-Like Field Effect Transistor

A transistor comprising:

• a fin;
• a first epitaxial source/drain feature disposed in a first source/drain region of the fin and a second epitaxial source/drain feature disposed in a second source/drain region of the fin;
• a gate structure disposed over the fin between the first epitaxial source/drain feature and the second epitaxial source/drain feature, wherein the gate structure includes:
• a gate electrode,
• a gate dielectric,
• a gate air spacer seal,
• a first gate air spacer confined between the gate dielectric, a first sidewall of the gate electrode, and the gate air spacer seal, and
• a second gate air spacer confined between the gate dielectric, a second sidewall of the gate electrode, and the gate air spacer seal;
• and
• a gate contact that extends through the gate air spacer seal to the gate electrode.

A method comprising:

• after forming a first epitaxial source/drain feature and a second epitaxial source/drain feature, removing gate spacers from along sidewalls of a dummy gate stack disposed over a fin between the first epitaxial source/drain feature and the second epitaxial source/drain feature;
• replacing the dummy gate stack with a metal gate stack, wherein the metal gate stack includes a gate electrode disposed over a gate dielectric and a dummy spacer disposed between the gate dielectric and sidewalls of the gate electrode;
• removing the dummy spacer from the metal gate stack to form a gate air spacer in the metal gate stack between the gate dielectric and the sidewalls of the gate electrode;
• and
• forming a gate air spacer seal over the gate air spacer.