Method of manufacturing an organic light-emitting display device

A method of manufacturing an organic light-emitting display device, the method comprising:

• a first mask operation comprising forming a semiconductor layer on a substrate, and forming an active layer of a thin film transistor and a lower capacitor electrode by patterning the semiconductor layer;
• a second mask operation comprising forming a first insulating layer on the substrate so as to cover the active layer and the lower capacitor electrode, sequentially stacking a first conductive material on the first insulating layer, and a second conductive material with a different etching selectivity ratio from the first conductive material on the first insulating layer, forming, by patterning, a gate electrode comprising the first conductive material and the second conductive material, and forming, by patterning, an upper capacitor electrode comprising the first conductive material;
• a third mask operation comprising forming a second insulating layer on a resulting structure of the second mask operation, and forming contact holes exposing a portion of the active layer by patterning the second insulating layer;
• and
• a fourth mask operation comprising forming a third conductive material on a resulting structure of the third mask operation, forming source and drain electrodes by patterning the third conductive material, and forming a pixel electrode by extending one of the source and the drain electrode so as to cover an area comprised of an entire portion where the upper capacitor electrode is formed.