Patent ID: 7977128

Claim:
A method of forming an array substrate of a liquid crystal display device, comprising: forming a first metallic layer on a substrate; forming a first copper (Cu) layer on the first metallic layer; patterning the first metallic layer and the first Cu layer simultaneously using a first etchant to form a gate line and a gate electrode, the first etchant includes hydrogen peroxide (H 2 O 2 ), a phosphate, F-ions, an organic acid having a carboxyl group (—COOH), a copper (Cu) inhibitor, and a hydrogen peroxide (H 2 O 2 ) stabilizer; forming a gate insulating layer over an entire surface of the substrate to cover the gate line and the gate electrode; forming an active layer and an ohmic contact layer on the gate insulating layer and over the gate electrode; forming a second metallic layer and a second copper (Cu) layer over the gate insulating layer to cover the active layer and the ohmic contact layer; patterning the second metallic layer and the second Cu layer simultaneously using a second etchant to form a source electrode, a drain electrode, and a data line, the second etchant includes hydrogen peroxide (H 2 O 2 ), a phosphate, F-ions, an organic acid having a carboxyl group (—COOH), a copper (Cu) inhibitor, and a hydrogen peroxide (H 2 O 2 ) stabilizer; forming a passivation layer over the gate insulating layer to cover the source and drain electrodes and the data line, the passivation layer having a drain contact hole exposing a portion of the data line; and forming a pixel electrode on the passivation layer, the pixel electrode contacting the drain electrode through the drain contact hole.