SEMICONDUCTOR DEVICE

A semiconductor device includes: a substrate including an upper surface and a lower surface opposite to the upper surface; an active pattern disposed on the upper surface of the substrate and extending in a first direction; a field insulating film disposed on the upper surface of the substrate and covering a sidewall of the active pattern; a power rail disposed on the lower surface of the substrate and extending in the first direction; a trench formed in the substrate and exposing a portion of the power rail; and a metal pattern filling at least a portion of the trench and connected to the power rail, wherein a bottom surface of the trench is substantially coplanar with the lower surface of the substrate, wherein a sidewall of the trench has a convex shape, and wherein at least a portion of the field insulating film is disposed in the trench.