A method of manufacturing a semiconductor device including operations of forming a first hard mask over an underlying layer on a substrate by a photolithographic and etching method, forming a sidewall spacer pattern having a first sidewall portion and a second sidewall portion on opposing sides of the first hard mask, etching the first sidewall portion, etching the first hard mask and leaving the second sidewall portion bridging a gap of the etched first hard mask, and processing the underlying layer using the second hard mask.