US Patent 9305835 Formation of air-gap spacer in transistor

Embodiments of present invention provide a method of forming air spacers in a transistor structure. The method includes forming a gate structure of a transistor on top of a semiconductor substrate; forming a first and a second disposable spacers adjacent to a first and a second sidewall of the gate structure; forming a first and a second conductive studs next to the first and the second disposable spacer; removing the first and second disposable spacers to create empty spaces between the first and second conductive studs and the gate structure; and preserving the empty spaces by forming dielectric plugs at a top of the empty spaces.