The present application provides a method of manufacturing a semiconductor structure. The method includes: forming a dielectric layer over a substrate; forming an opening in the dielectric layer; forming a first liner conformal to the opening; forming a porous layer in the opening and surrounded by the first liner; forming a conductive via penetrating the dielectric layer; and forming a conductive pad over the dielectric layer, wherein the conductive pad covers the porous layer and the conductive via.