A method for fabricating a semiconductor device includes forming an etch-target layer over a substrate having a first region and a second region, stacking first and second hard mask layers over the etch-target layer, forming spacer patterns over the second hard mask layer of the first area, etching the second hard mask layer using the spacer patterns as an etch barrier, forming a hard mask pattern over the first hard mask layer of the second region, etching the first hard mask layer using the second hard mask layer of the first region and the hard mask pattern of the second region as etch barriers, removing the hard mask pattern of the second region, and etching the etch-target layer using the first and second hard mask layers of the first region and the first hard mask layer of the second region as etch barriers.