according to an aspect of the present invention , there is provided a method of manufacturing a semiconductor device , the method including : forming a first film on a target film ; forming resist patterns on the first film ; processing the first film with the resist patterns to form first patterns including : periodic patterns ; and aperiodic patterns ; removing the resist patterns ; forming a second film over the target film ; processing the second film to form second side wall patterns on side walls of the first patterns ; removing the periodic patterns ; and processing the target film with the aperiodic patterns and the second side wall patterns , thereby forming a target patterns including : periodic target patterns ; aperiodic target patterns ; and dummy patterns arranged between the periodic target patterns and the aperiodic patterns and arranged periodically with the periodic target patterns .