A method of forming an integrated circuit includes forming at least one opening through a first surface of a substrate. The method further includes forming at least one conductive structure in the at least one opening. The method further includes removing a portion of the substrate to form a processed substrate having the first surface and a second surface opposite the first surface and to expose a portion of the at least one conductive structure adjacent to the second surface. The at least one conductive structure continuously extending from the first surface through the processed substrate to the second surface of the processed substrate, at least one sidewall of the at least one conductive structure spaced from a sidewall of the at least one opening by an air gap.