Array substrate for LCD device having metal-diffusion film and manufacturing method thereof

An array substrate for use in a liquid crystal display device, comprising:

• a gate electrode, a gate line and a gate pad electrode on a substrate, wherein all of the gate electrode, the gate line and the gate pad electrode have a first barrier metal layer, a first copper layer, and a first out-diffusion film that covers a side surface of the first copper layer and a first surface of the first copper layer opposite to a second surface of the first copper layer that contacts the first barrier layer, and wherein the first out-diffusion film is a metal alloy film of molybdenum and copper;
• a gate insulation layer on the substrate covering the gate electrode, gate line and gate pad;
• an active layer and an ohmic contact layer on the gate insulation layer and over the gate electrode;
• a data line on the gate insulation layer crossing the gate line;
• source and drain electrodes contacting the ohmic contact layer;
• a data pad electrode on the gate insulation layer;
• a passivation layer formed on the gate insulation layer covering the data line, source and drain electrodes, and data pad electrode, wherein the passivation layer has a drain contact hole exposing a portion of the drain electrode, a gate pad contact hole exposing a portion of the gate pad electrode, and a data pad contact hole exposing a portion of the data pad electrode;
• and
• a pixel electrode, a gate pad terminal and a data pad terminal are made of a transparent conductive material on the passivation layer.