US Patent 10074558 FinFET structure with controlled air gaps

The present disclosure provides a method that includes forming an isolation feature in a semiconductor substrate; forming a first fin and a second fin on the semiconductor substrate, wherein the first and second fins are laterally separated by the isolation feature; and forming an elongated contact feature landing on the first and second fins. The elongated contact feature is further embedded in the isolation feature, enclosing an air gap vertically between the contact feature and the isolation feature.