A thin film transistor substrate includes a substrate, a bottom gate on the substrate, a first insulating layer on the substrate and on the bottom gate, a drain on the first insulating layer, a source on the first insulating layer, the source including a first source at a first side of the drain and a second source at a second side of the drain, an active layer on the first insulating layer, the active layer including a first active layer contacting the drain and the first source and a second active layer contacting the drain and the second source, a second insulating layer on the drain, the source, and the active layer, and a top gate on the second insulating layer.