CHEMICAL ETCHING SOLUTION FOR TUNGSTEN OR AN ALLOY OF TUNGSTEN-TITANIUM

摘要

An etching solution for tungsten or a titanium-tungsten metal alloy is provided to etch an under bumper metal of a flip chip without attacking a copper UBM(Under bumper metallurgy) layer or rapidly disintegrating a hydrogen peroxide by using the etching solution containing 0.001 to 2% of a copper corrosion inhibiting agent by weight, wherein the copper inhibiting agent is an azole based chemical compound, 5 to 30% of hydrogen peroxide by weight, 0.001 to 2% of a stabilizer by weight, and the water making up the rest of the total weight of the etching solution. An etching solution for tungsten or a titanium-tungsten metal alloy contains 5 to 30% of hydrogen peroxide by weight as a main oxidizer, 0.01 to 5% of a stabilizer by weight, 0.001 to 2% of a copper corrosion inhibiting agent and water making up the rest of the total weight of the etching solution. The stabilizer is a phosphoric acid or a phosphate. The copper corrosion inhibiting agent is an azole based chemical compound. The phosphoric acid or the phosphate is selected from a group consisting of a monoammonium phosphate, a diammonium phosphate, an ammonium phosphate, a monosodium phosphate, a disodium phosphate, a trisodium phosphate, a monopotassium phosphate, a dipotassium phosphate, a tribasic potassium phosphate, a diphosphoric acid, a sodium diphosphoric acid, a potassium pyro phosphate, and an ammonium diphosphoric acid. The azole based chemical compound is selected from a group consisting an aminotetrazole, a mercapto-thiazole, a benzotriazole, a hydroxyl-thiazole, an amino-benzotriazole, an amino-thiazole, an acetylimidazole, an acetyle-thiazole, an amino-triazole, and a benzlimidazole. The etching solution is used to etch an under bump metal of a flip chip. The under bump metal contains the tungsten or the titanium-tungsten metal alloy. A solder bump which is a metal contact layer of the under bump metal, is composed of a copper/tin-silver metal alloy.