| abstract |
(57) [PROBLEMS] To use a low-resistance Cu film as a wiring material, the Cu film can be etched by a simple chemical etching method called an immersion method at rest, and the change in etching rate with time is small, and the Cu film is small. To provide an etchant capable of preventing a pattern thinning phenomenon caused by a variation in the amount of side etching. An etching agent comprising an aqueous solution containing potassium peroxomonosulfate and hydrofluoric acid. A mask 27, 28 having a predetermined pattern is formed on the surface of a laminated film in which a Ti film or a Ti alloy 3 and a Cu film 4 are sequentially formed on the base 2, A method of manufacturing a thin film transistor substrate in which the gate electrode 5 (stacked wiring) and the lower pad layer (stacked wiring) 16b of the predetermined pattern are formed by etching the stacked film using the etching agent having the above configuration. |