Etchant composition, methods of patterning conductive layer and manufacturing flat panel display device using the same

A method of manufacturing a flat panel display device, comprising:

• providing a substrate;
• forming a first conductive layer on the substrate;
• patterning the first conductive layer to form a gate electrode;
• forming a gate insulating layer on the gate electrode;
• forming a semiconductor layer on the gate insulating layer corresponding to the gate electrode;
• forming a second conductive layer on the semiconductor layer;
• patterning the second conductive layer to form source/drain electrodes;
• forming a passivation layer over an entire surface of the substrate including the source/drain electrodes, wherein the passivation layer has a contact hole exposing a portion of the drain electrode;
• and
• forming a third conductive layer on the passivation layer to be electrically connected to the drain electrode through the contact hole;
• and patterning the third conductive layer to form a pixel electrode,
• wherein the gate electrode, the source/drain electrodes and the pixel electrode are patterned using the same etchant composition;
• and
• wherein the etchant composition comprises phosphoric acid having a concentration of about 40 to 70 wt %, nitric acid having a concentration of about 3 to 15 wt %, acetic acid having a concentration of about 5 to 35 wt %, a chlorine-based compound having a concentration of about 0.02 to 5 wt %, a nitrate-based compound having a concentration of about 0.05 to 5 wt %, a sulfate-based compound having a concentration of about 0.05 to 5 wt %, an oxidation regulator having a concentration of about 1 to 10 wt %, and a residual quantity of water.