Thin film transistor substrate and method for making same

Provide a thin film transistor substrate, comprising a first thin film transistor and a second thin film transistor. A first thin film transistor includes a first active layer, a first gate insulating film and the first gate electrode. A second active layer includes forming a second thin film transistor, the second gate insulating film and the second gate electrode. The thickness of second gate insulating film is greater than the thickness of the first gate insulating film, a second active layer having at least two impurity-doped region overlapping the second gate electrode, a first active layer having at least two with respect to the first impurity gate electrode is formed in a self-aligned doped regions, and a second gate electrode comprising a semiconductor layer.