A display device includes a gate line and a data line crossing each other to form a pixel; a thin film transistor (TFT) near the crossing, the TFT including a polycrystalline silicon layer, wherein the polycrystalline silicon layer includes a plurality of first, second and third circular crystals, and the three first, second and third adjacent circular crystals form one equilateral triangle, and six of the equilateral triangles form a regular hexagon, wherein the second crystals are grown radially staffing from circumferences of the first crystals and wherein the third crystals are grown radially starting from circumferences of the first or second crystals.