US Patent 10510861 Gaseous spacer and methods of forming same

A method for forming a gaseous spacer in a semiconductor device and a semiconductor device including the gaseous spacer are disclosed. In an embodiment, the method may include forming a gate stack over a substrate, depositing a first gate spacer on sidewalls of the gate stack, epitaxially growing source/drain regions on opposite sides of the gate stack, and depositing a second gate spacer over the first gate spacer to form a gaseous spacer below the second gate spacer. The gaseous spacer may be disposed laterally between the source/drain regions and the gate stack.