Abstract: An etching method for quickly removing a seed layer that is formed of titanium and/or a titanium alloy, while suppressing dissolution of other metals from copper wiring lines and the like, for continuous and stable processing; and a composition which is used for this etching method. The composition comprises, based on a total amount of the composition, 0.01 to 0.23% by mass hydrogen peroxide, 0.2 to 3% by mass fluoride, 0.0005 to 0.025% by mass of a halide ion other than a fluoride ion, and water. A method for using the composition to produce a substrate is also described.

Abstract: The present invention provides: an aqueous composition capable of removing a photoresist from a printed wiring board or a semiconductor wafer while preventing corrosion of tin plating and tin alloy plating in addition to a copper wiring; and a method for removing a photoresist using the aqueous composition. The aqueous composition according to the present invention is characterized by comprising an alkanolamine (A), a quaternary ammonium hydroxide (B), a sugar alcohol (C), a polar organic solvent (D), and water (E), wherein, with respect to the total amount of the composition, the content of the alkanolamine (A) is 2.5-50 mass %, the content of the quaternary ammonium hydroxide (B) is 0.5-4 mass %, and the content of the sugar alcohol (C) is 0.5-20 mass %.