A method includes forming a plurality of first line-shaped mask patterns over a substrate including a memory cell region and an array edge region; forming a plurality of second line-shaped mask patterns over the plurality of first line-shaped mask patterns; removing first portions from the plurality of first line-shaped mask patterns in the memory cell region to leave a plurality of island-shaped mask patterns above the memory cell region; removing second portions from the plurality of first line-shaped mask patterns in the array edge region to leave a holes-provided mask pattern above the array edge region; forming a mask pattern which includes a plurality of holes provided on portions; and forming, with the mask pattern which includes the plurality of holes, a plurality of contact holes in the array edge region to provide a plurality of contact electrodes connected to a plurality of word-lines.