An integrated circuit device may include a pair of line structures. Each line structure may include a pair of conductive lines extending over a substrate in a first horizontal direction and a pair of insulating capping patterns respectively covering the pair of conductive lines. The integrated circuit device may include a conductive plug between the pair of line structures and a metal silicide film contacting a top surface of the conductive plug between the pair of insulating capping patterns. The conductive plug may have a first width between the pair of conductive lines and a second width between the pair of insulating capping patterns, in a second horizontal direction perpendicular to the first horizontal direction, where the second width is greater than the first width.