Array substrate, method for producing the same and display device

A method for producing an array substrate, comprising:

• forming a pattern of a first gate on a substrate;
• forming a first gate insulation layer on the substrate subjected to the preceding step;
• forming an active layer on the substrate subjected to the preceding steps;
• forming a second gate insulation layer on the substrate subjected to the preceding steps;
• forming a pattern of a second gate on the substrate subjected to the preceding steps;
• source and drain-heavily doping and source and drain-lightly doping two side regions outside a region of the active layer corresponding to the second gate respectively, wherein the lightly doped source region and the lightly doped drain region are immediately adjacent to the active layer corresponding to the second gate, the heavily doped source region is immediately adjacent to the lightly doped source region, and the heavily doped drain region is immediately adjacent to the lightly doped drain region;
• forming a third gate insulation layer on the substrate subjected to the preceding steps, and forming via holes thereon;
• forming a pattern of source and drain electrodes on the substrate subjected to the preceding steps, wherein the source and drain electrodes are electrically connected with the heavily doped source and drain regions through the via holes, respectively;
• wherein the first gate is provided below the lightly doped drain region corresponding to the drain electrode, or the first gate includes a first sub part of the first gate and a second sub part of the first gate, which are respectively provided below the lightly doped source region and the lightly doped drain region corresponding to the source and drain electrodes respectively.