ETCHING OF ALLOY OF TITANIUM AND TUNGSTEN AND ETCHANT SOLUTION

摘要

PROBLEM TO BE SOLVED: To remove a thin film of a metal layer under the existence of the metal layer to be protected by a method wherein metal layers are subjected to wet chemical etching in the specified range of the pH of an etchant solution. SOLUTION: During the manufacture of a C4 solder bump using an electroplating, a metal blanket stack 3 can be deposited on a functional silicon wafer 2. It is preferable that the stack 3 has a TiW layer 6, a CrCu layer 8 and a Cu layer 8. After an electrodeposition of solder and the removal of a photomask, the stack 3 is removed. The layers 10 and 8 are subjected to electroetching and after that, the thin layer of the layer 6 is left. The layer 6 is etched in a solution containing a hydrogen peroxide, a potassium sulfate and an EDTA potassium. In the range that the pH of the etchant solution is about 2.7 to 4.0, the desired efficiency of the manufacture of a C4 device is obtained and most of defects, which are accompanied by etching of the layer 6, are eliminated.