ETCHING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method of controlling an etching solution reducing the amount of cerium ammonium nitrate and perchloric acid and also giving an excellent etching face in a method of subjecting a chromium film to etching with an etching solution containing cerium ammonium nitrate and perchloric acid. SOLUTION: The amount of cerium ammonium nitrate is controlled in such a manner that the weight ratio of tetravalent cerium to hexavalent chromium in an etching solution regulated to 40 to 60.