Method of manufacturing OLED display including thin film transistor having both source and drain formed over and patterned together with semiconductor layer

A method of manufacturing an organic light-emitting diode (OLED) display, the method comprising:

• first forming a semiconductor material layer and a first metal layer over a substrate, wherein the first metal layer is formed over the semiconductor material layer;
• first patterning the semiconductor material layer and the first metal layer so as to form an active layer, a source electrode, and a drain electrode of a thin film transistor (TFT);
• second forming a first insulating layer including a portion corresponding to the active layer;
• third forming a second metal layer over the active layer, the source electrode and the drain electrode;
• second patterning the second metal layer so as to form a gate electrode on the portion of the first insulating layer;
• fourth forming a second insulating layer, having a via hole, over the first insulating layer so as to cover the gate electrode, wherein the via hole exposes one of the source and drain electrodes;
• fifth forming a third metal layer over the second insulating layer;
• third patterning the third metal layer so as to form a pixel electrode electrically connected to one of the source and drain electrodes through the via hole;
• and
• sixth forming a third insulating layer over the second insulating layer so as to cover edges of the pixel electrode and expose the remaining portion of the pixel electrode.