Etchant and method of etching

Abstract

A fine wiring line profile with satisfactory precision is formed from a multilayer film containing a first layer made of an aluminum alloy and a second layer formed thereon made of a molybdenum-niobium alloy, by simultaneously etching the two layers constituting the multilayer film through only one etching operation while preventing the upper layer from forming overhangs. An etchant for etching a multilayer film containing an aluminum alloy layer formed over a substrate and a molybdenum-niobium alloy layer formed thereon having a niobium content of 2-19% by weight contains an aqueous solution of an acid mixture containing phosphoric acid, nitric acid, and an organic acid; and a method of etching is carried out with this etchant. The etchant preferably has a phosphoric acid concentration Np of 50-75% by weight, a nitric acid concentration Nn of 2-15% by weight, and an acid ingredient concentration defined by Np+(98/63)Nn of 55-85% by weight.

Dependencies are inferred from the claim text.