Method of fabricating semiconductor device

Provided is a method for fabricating a semiconductor device, including forming an interconnect structure including first and second interconnects and an insulating material between the first and second interconnects, forming a first mask layer and a second mask layer having a plurality of micropores sequentially on the interconnect structure, coalescing the plurality of micropores in the second mask layer with each other and forming a plurality of first microholes in the second mask layer, forming a plurality of second microholes in the first mask layer using the plurality of first microholes, and removing the insulating material using the first mask layer with the plurality of second microholes as an etch mask so as to form an air-gap between the first and second interconnects.