A memory device including a plurality of first conductive lines arranged on a substrate and spaced apart from each other in a first direction parallel to a top surface of the substrate; a plurality of capping liners on sidewalls of each of the plurality of first conductive lines, the plurality of capping liners having top surfaces at a vertical level equal to top surfaces of the plurality of first conductive lines, and bottom surfaces at a vertical level higher than bottom surfaces of the plurality of first conductive lines; and an insulating layer on the substrate, the insulating layer filling spaces between the plurality of first conductive lines and covering sidewalls of the plurality of capping liners.