A semiconductor device and a manufacturing method of the same are provided. The method includes forming a plurality of first conductive structures and a first dielectric layer between the first conductive structures on a substrate. The method also includes forming a trench between the first dielectric layer and the first conductive structures. The method further includes forming a liner material on a sidewall and a bottom of the trench. In addition, the method includes forming a conductive plug on the liner material in the trench. The method also includes removing the liner material to form an air gap, and the air gap is located between the conductive plug and the first dielectric layer.