SEMICONDUCTOR DEVICES

A semiconductor device includes: insulating patterns spaced apart from each other in a first direction and in a second direction that intersects the first direction; a substrate insulating layer on first side surfaces of the insulating patterns; a device isolation layer on second side surfaces of the insulating patterns; channel layers on the insulating patterns and spaced apart from each other in a vertical direction that is perpendicular to an upper surface of the device isolation layer; gate structures vertically overlapping the insulating patterns, surrounding each of the channel layers, and extending in the second direction; source/drain regions provided outside the gate structures; and backside contact structures electrically connected to the source/drain regions and provided below the source/drain regions, wherein the insulating patterns include protrusions protruding in the vertical direction from an upper surface of the device isolation layer, and, in a region in which the insulating patterns vertically overlap the gate structures, a vertical distance between a lower surface of a lowermost channel layer among the channel layers and an upper surface of the protrusions is greater than a vertical distance between the channel layers.