▎ 摘　　要

NOVELTY - Etching solution comprises 15-20 pts. wt. phosphoric acid, 5-10 pts. wt. nitric acid, 8-20 pts. wt. ultra-pure ammonium fluoride, 3-8 pts. wt. triethanolammonium salt and 10-15 pts. wt. water. The preparation method of the ultra-pure ammonium fluoride comprises (1) heating industrial-grade liquid ammonia at 60-70degrees Celsius to release ammonia gas, adsorbing the ammonia gas by activated carbon to remove impurities, and adsorbing and deoxidizing to obtain high-purity ammonia gas, and (2) introducing high-purity ammonia gas and hydrogen fluoride into fluidized bed reactor, and performing reaction at temperature of 80-90degrees Celsius for 5-7 hours to obtain ultra-pure ammonium fluoride. USE - The etching solution is useful for microelectronics (claimed). ADVANTAGE - The anti-corrosive paint can well protect the fluidized bed reactor from being corroded by hydrofluoric acid. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing etching solution, comprising taking phosphoric acid, nitric acid, ultra-pure ammonium fluoride, triethanolammonium salt and water, and uniformly mixing the raw materials.