A semiconductor device including a substrate having isolation films and active regions that are defined by the isolation films. The active regions extend in a first direction. A first trench is disposed on the substrate. Second trenches are disposed in the active regions. A filling film is disposed in the first trench. First gate patterns are disposed on the filling film in the first trench. Second gate patterns are disposed in the second trenches. The second gate patterns extend in a second direction that is different from the first direction. The filling film includes at least one material selected from a semiconductor material film and a metal.