SEMICONDUCTOR DEVICE

A semiconductor device comprises a substrate including a first surface and a second surface opposite to each other in a first direction, an active pattern on the first surface of the substrate and extending in a second direction, a field insulating film on the first surface of the substrate and covering sidewalls of the active pattern, a power rail on the second surface of the substrate and extending in the second direction, a via trench on one side of the active pattern and penetrating through the field insulating film, and a power rail via filling the via trench and connected to the power rail, in which the power rail via includes a first sub-film formed as a single film, and a second sub-film on the first sub-film and including barrier films extending along inner sidewalls of the via trench and a filling film between the barrier films.