A semiconductor device includes a base substrate, a first transistor disposed on the base substrate, the first transistor including a first input electrode, a first output electrode, a first control electrode, and a first semiconductor pattern including a crystalline semiconductor, a second transistor disposed on the base substrate, the second transistor including a second input electrode, a second output electrode, a second control electrode, and a second semiconductor pattern including an oxide semiconductor, a plurality of insulating layers disposed on the base substrate, and an upper electrode disposed on the first control electrode with at least one insulating layer of the plurality of insulating layers interposed between the upper electrode and the first control electrode. The upper electrode overlaps the first control electrode and forms a capacitor with the first control electrode.