Semiconductor devices

A semiconductor device including an active pattern on a substrate and extending lengthwise in a first direction parallel to an upper surface of the substrate; a gate structure on the active pattern, the gate structure extending in a second direction parallel to the upper surface of the substrate and crossing the first direction; channels spaced apart from each other along a third direction perpendicular to the upper surface of the substrate, each of the channels extending through the gate structure along the first direction; a source/drain layer on a portion of the active pattern adjacent to the gate structure in the first direction, the source/drain layer contacting the channels; inner spacers between the gate structure and the source/drain layer, the inner spacers contacting the source/drain layer; and channel connection portions between each of the inner spacers and the gate structure, the channel connection portions connecting the channels with each other.