depositing a base layer on a substrate;

forming a first hard mask layer on the base layer;

forming a second hard mask layer on the first hard mask layer;

forming a first etch mask pattern on the second hard mask layer wherein the first etch mask pattern is repeatedly formed having a first pitch;

forming a buffer layer on a surface of a resultant structure having the first etch mask pattern;

forming a second etch mask pattern on the buffer layer using a photolithography process, wherein the second etch mask pattern is repeatedly formed having the first pitch between the first etch mask pattern;

etching the buffer layer using the second etch mask pattern as an etch mask, forming a buffer layer pattern;

etching the second hard mask layer using the first etch mask pattern and the buffer layer pattern as etch masks, forming a second hard mask pattern having a second pitch wherein the second pitch is a half of the first pitch;

etching the first hard mask layer using the second hard mask pattern as an etch mask, forming a first hard mask pattern which is repeatedly formed having the second pitch; and

etching the base layer using the first hard mask pattern as an etch mask, forming a pattern which is repeatedly formed having the second pitch.