Process of selective trapping of silicon tetrafluoride comprises introducing gas stream comprising nitrogen, hydrogen, silane and silicon tetrafluoride in trapping reactor containing metal fluoride which is solid adsorbent

摘要

Process of selective trapping of silicon tetrafluoride comprises: introducing a gas stream comprising 60-75% of nitrogen (N 2), 20-35% of hydrogen (H 2), 1.5-4% of silane (SiH 4) and 100 ppm of 0.3% of silicon tetrafluoride (SiF4), in a trapping reactor (40) containing a metal fluoride which does not react with SiF 4, where the metal fluoride is a solid adsorbent (A). Process of selective trapping of silicon tetrafluoride comprises: introducing a gas stream comprising 60-75% of nitrogen (N 2), 20-35% of hydrogen (H 2), 1.5-4% of silane (SiH 4) and 100 ppm of 0.3% of silicon tetrafluoride (SiF4), in a trapping reactor (40) containing a metal fluoride which does not react with SiF 4, where the metal fluoride is a solid adsorbent of formula (nF 2/nM) (A). M : an alkali metal comprising Li, Na, K, Rb, Cs or Fr (when n is 2 ) or an alkaline earth metal comprising Be, Mg, Ca, Sr, Ba or Ra (when n is 1). An independent claim is included for process-I for recycling SiH 4and H 2comprising: (a) injecting a pure SiH 4/H 2mixture in a reaction chamber (7) to produce thin films containing silicon; (b) extracting the mixture using a pump (8) having N 2as supply gas; (c) discharging a mixture comprising SiH 4, H 2, SiF 4and a non-zero amount of nitrogen from the pump (8) at a pressure close to atmospheric pressure; and (d) separating SiF 4from mixture of SiH 4/H 2/N 2from step (c), where at least 50%, preferably 80% of SiH 4from step (b) is reused after step (d) for a further step (a).