A method of ammonia gas purification for manufacturing highly pure nitrogen trifluoride

摘要

PURPOSE: Provided is a purification method of ammonia gas used as a raw material in nitrogen trifluoride(NF3) preparation by applying NH3 gas to thermal-treated zeolite. Accordingly, the resultant NH3 gas offers high purity NF3 gas for semiconductor cleaning. CONSTITUTION: The ammonia gas is purified by passing NH3 gas through a synthetic zeolite column(10-100cm height) in a rate of 30-150ml/min for removing water and oil contained in NH3, causing the formation of impurities, N2O and CF4. The synthetic zeolite, such as a molecular sieve 3A, 4A, 5A and 13X, used as an adsorbent is thermally treated at 200-500deg.C for 5-24hrs and preferably 200-300deg.C for 8-14hrs in an inert gas atmosphere such as N2, Hw, Ne or Ar.