A display device includes: a substrate; and a semiconductor layer disposed on the substrate, and including a first area, a second area, and a third area that are sequentially positioned by dividing the semiconductor layer into three areas in a thickness direction of the semiconductor layer, wherein the semiconductor layer includes polycrystalline silicon, a concentration of fluorine contained in the semiconductor layer has a first peak value in the first area and a second peak value in the third area, and the first peak value of the concentration of the fluorine in the semiconductor layer is about 30% or less of the second peak value of the concentration of the fluorine in the semiconductor layer.