A semiconductor memory device includes a semiconductor substrate defining active regions partitioned by an isolation region, conductive lines spaced apart from each other and crossing the active regions over the semiconductor substrate, a thin film pattern formed on a top portion of the conductive lines having opening portions exposing part of the conductive lines in a width wider than a width of the conductive lines, an insulating layer filling the opening portions and formed over the thin film pattern, and an air gap formed between the conductive lines below the insulating layer and the thin film pattern.