The present disclosure provides a method for forming patterns in a semiconductor device. In accordance with some embodiments, the method includes providing a substrate, a patterning-target layer over the substrate, and a hard mask layer over the patterning-target layer; forming a first pattern in the hard mask layer; removing a trim portion from the first pattern in the hard mask layer to form a trimmed first pattern; forming a first resist layer over the hard mask layer; forming a main pattern in the first resist layer; and etching the patterning-target layer using the main pattern and the trimmed first pattern as etching mask elements to form a final pattern in the patterning-target layer. In some embodiments, the final pattern includes the main pattern subtracting a first overlapping portion between the main pattern and the trimmed first pattern.