A display device includes an array substrate defined with a plurality of pixel structures arranged in an array. Each of the pixel structures includes a semiconductor layer disposed over a substrate and a first metal layer disposed over the substrate. The pixel structure includes a first insulating layer disposed over the semiconductor layer, having a first opening exposing a top surface of the semiconductor layer and a sidewall surface of the first insulating layer. The pixel structure includes a metal pad disposed over the first insulating layer, being formed over the top surface of the semiconductor layer and the sidewall surface of the first insulating layer through the first opening. The pixel structure includes a second insulating layer disposed over the metal pad and the first insulating layer, having a second opening exposing the metal pad over the sidewall surface of the first insulating layer.