A semiconductor structure includes a substrate. A first metallization layer is disposed on the substrate. A second metallization layer is disposed on the first metallization layer and having one or more openings, wherein at least one of the one or more openings is configured to expose a top surface of the first metallization layer. A polymer-adhering liner layer is disposed on sidewalls of the at least one of the one more openings in the second metallization layer. A dielectric polymer is disposed in the at least one of the one or more openings in the second metallization layer and on the polymer-adhering liner layer. The dielectric polymer is configured to seal an air gap in the dielectric polymer.