Etching solution for etching layer system, comprising phosphoric acid, nitric acid, de-ionized water and halogen component, which releases halogen ions that contain these components

摘要

An etching solution comprises an aluminum layer (1), a copper layer (2) and a layer selected from a nickel-vanadium layer (3), nickel and alloys of nickel, which are arranged between an aluminum layer and a copper layer. The solution contains phosphoric acid, nitric acid, de-ionized water and a halogen component, which releases halogen ions containing these components. The metal cation salts are selected, which are contained in the layer system. Independent claims are also included for the following: (1) the structuring of a layer system involves selecting layers from aluminum, copper, nickel vanadium, nickel and their alloys; and (2) an Under Bump Metallization stack.