A flat panel display including a semiconductor circuit, and a method of manufacturing the semiconductor circuit are disclosed. In one embodiment, the semiconductor circuit includes i) a substrate, ii) a semiconductor layer and a first capacitor electrode formed on the substrate, the first capacitor electrode being doped to be conductive, iii) an insulating layer covering the semiconductor layer and the first capacitor electrode, iv) a gate electrode disposed on the insulating layer and corresponding to a portion of the semiconductor layer, and v) a second capacitor electrode disposed on the insulating layer and corresponding to the first capacitor electrode, wherein the gate electrode is thicker than the second capacitor electrode.