PURPOSE: To simply manufacture an array substrate without producing a hillock on the surface of aluminum.

CONSTITUTION: An aluminum alloy is deposited, in 200nm, on a glass substrate 1 by a sputtering method, it is patterned, a scanning line 2 used also as a gate is formed, and a surface oxide film which has been produced on the surface is removed by a reverse sputtering method. A molybdenum-tantalum alloy (MoTa) film 16 is deposited, in 150nm, on the scanning line 2 used also as the gate, it is annealed at 430°C for one hour in a vacuum annealing furnace, and an aluminum alloy layer 17 is formed on the surface. After the aluminum alloy layer 17 has been formed, only the molybdenum-tantalum alloy film 16 is dry-etched and removed. A semiconductor layer 10 is formed, and a display electrode 12 is formed by using an ITO as a material. An aluminum layer is deposited, and a signal line 14 used also as a source electrode and a drain electrode 13 are formed.