Air-gap offset spacer in FinFET structure

A method of forming a FinFET device, comprising:

• forming one or more fins of semiconductor material on a semiconductor substrate laterally between sections of isolating material;
• forming a sacrificial gate structure protruding from the substrate at a position overlying the one or more fins of semiconductor material;
• forming a source region and a drain region on opposite ends of the sacrificial gate structure at positions contacting the fin of semiconductor material;
• forming a first layer of insulating material onto sidewalls of the sacrificial gate structure and over the one or more fins of semiconductor material;
• forming a sacrificial air gap layer onto sidewalls of the first layer of insulating material, wherein the sacrificial air gap layer has a bottom surface that vertically contacts the first layer of insulating material along a first horizontal interface that is above the source region and the drain region;
• forming a second layer of insulating material onto sidewalls of the sacrificial air gap layer, wherein the second layer of insulating material has a bottom surface that vertically contacts the sacrificial air gap layer along a second horizontal interface that overlies the source region and the drain region;
• and
• simultaneously removing the sacrificial air gap layer and the sacrificial gate structure, wherein removing the sacrificial air gap layer forms air gaps disposed between the first layer of insulating material and the second layer of insulating material.

A FinFET (Fin field effect transistor) device, comprising:

• a three-dimensional fin of semiconductor material protruding from a substrate at a location between first and second sections of isolating material;
• a gate structure overlying the three-dimensional fin of semiconductor material and configured to control a flow of charge carriers within a channel region disposed within the three-dimensional fin of semiconductor material;
• a first layer of insulating material that contacts opposite sides of the gate structure;
• and
• a second layer of insulating material that overlies the first layer of insulating material and that is separated laterally and vertically from the first layer of insulating material by an air gap layer.