A memory device includes a first floating gate electrode on a substrate between adjacent isolation layers in the substrate, at least a portion of the first floating gate protruding above a portion of the adjacent isolation layers, a second floating gate electrode, electrically connected to the first floating gate electrode, on at least one of the adjacent isolation layers, a dielectric layer over the first and second floating gate electrodes, and a control gate over the dielectric layer and the first and second floating gate electrodes.