Semiconductor device and method of fabricating the same

Abstract

According to example embodiments, a three-dimensional semiconductor device including a substrate with cell and connection regions, gate electrodes stacked on the cell region, a vertical channel structure, pads, a dummy pillar, and first and second semiconductor patterns. The vertical channel structure penetrates the gate electrodes on a lowermost gate electrode and includes a first gate dielectric pattern. The pads extend from the gate electrodes and are stacked on the connection region. The dummy pillar penetrates some of the pads on a lowermost pad and includes a second gate dielectric pattern. The first semiconductor patterns are between the vertical channel structure and the substrate. The second semiconductor patterns are between the dummy pillar and the substrate. The first and second gate dielectric patterns may be on the first and second semiconductor patterns, respectively. The second gate dielectric pattern may cover a whole top surface of the second semiconductor pattern.