Abstract: A method of fabricating a semiconductor device can include forming a channel hole in a vertical stack of alternating insulating and sacrificial layers to form a recess in a substrate. A selectively epitaxial growth can be performed to provide a lower semiconductor pattern in the recess using material of the substrate as a seed and a recess can be formed to penetrate an upper surface of the lower semiconductor pattern via the channel hole.

Abstract: A vertical NAND-type memory device includes a vertical stack of inter-gate insulating layers and gate electrodes arranged in an alternating sequence on an underlying substrate, which includes a cell array region and a contact region therein. At least one NAND-type channel structure is provided, which extends vertically through the vertical stack of inter-gate insulating layers and gate electrodes. An end sidewall of a first of the gate electrodes, which extends laterally over at least a portion of the contact region, has a vertical slope that is less steep than vertical slopes of end sidewalls of a first plurality of the gate electrodes extending between the first of the gate electrodes and the substrate.

Abstract: Semiconductor devices are provided. A semiconductor device includes a stack of gate electrodes. The semiconductor device includes a channel material in a channel recess in the stack. The semiconductor device includes a channel pad on the channel insulating layer. The channel pad has a curved upper surface. Methods of manufacturing semiconductor devices are also provided.

Abstract: A semiconductor device, including gate electrodes perpendicularly stacked on a substrate; channel holes extending perpendicularly to the substrate, the channel holes penetrating through the gate electrodes, the channel holes having a channel region; gate pads extended from the gate electrodes by different lengths; and contact plugs connected to the gate pads, at least a portion of the gate pads having a region having a thickness less than a thickness of the gate electrode connected to the at least a portion of the gate pads.