An active device array substrate has at least one patterned conductive layer. The patterned conductive layer includes a copper layer. A cross-section of the copper layer which is parallel to a normal line direction of the copper layer includes a first trapezoid and a second trapezoid stacked on the first trapezoid. A base angle of the first trapezoid and a base angle of the second trapezoid are acute angles, and a difference between the base angle of the first trapezoid and the base angle of the second trapezoid is from about 5° to about 30°.