A semiconductor device may include a linear gate trench that crosses an active region of a substrate of the semiconductor device. The active region may include a plurality of gate areas at a bottom of the gate trench and junction areas at a surface of the substrate in a central portion and opposite end portions of the active region. A conductive line may be in a lower portion of the gate trench. The conductive line may include a gate line and a capping layer that at least partially isolates the gate line from an upper surface of the conductive line. A sealing line may be in an upper portion of the gate trench. The sealing line may cover the conductive line and a surface of the sealing line may be coplanar with the junction areas.