An interconnect layout structure, having a plurality of air gaps, includes a substrate having an insulating material disposed thereon and a conductive line disposed in the insulating material and extending along a first direction. The air gaps are formed in the insulating material and are arranged end-to-end along the first direction and immediately adjacent to a same side of the conductive line. A patterned hard mask is disposed on the conductive line and has a sidewall extending along a second direction that is perpendicular to the first direction and passing between the adjacent air gaps from the top view. A via structure is formed on the conductive line and is electrically connected to the conductive line.