Semiconductor devices and methods of forming the same are provided. A semiconductor device according to one embodiment includes a first gate stack, a second gate stack, a first source/drain feature disposed between the first and second gate stacks, and a source/drain contact over and electrically coupled to the first source/drain feature. The source/drain contact is spaced apart from each of the first and second gate stacks by an inner spacer disposed on sidewalls of the source/drain contact, a first air gap, a first gate spacer, and a second air gap separated from the first air gap by the first gate spacer.