A display device includes a first substrate and an insulating layer over the first substrate. The display device further includes a semiconductor layer over the insulating layer and a dielectric layer over the semiconductor layer, having an opening partially exposing the semiconductor layer and the insulating layer, wherein the opening has a first width along a first direction. In addition, the display device further includes a conductive line extending over the dielectric layer along a second direction that is different from the first direction and filling the opening to electrically connect to the semiconductor layer exposed by the opening. The conductive line includes a first portion over a top surface of the dielectric layer and a second portion in the opening. The first portion of the conductive line has a second width along the first direction. The first width is greater than the second width.