A Purified Method Of NF₃ By Continuous Distillation In The Low Temperature

Nitrogen trifluoride (NF3) which is used as plasma etchant and cleaning gas forChemical Vapor Deposition (CVD) chambers is important for the development ofelectronic industries. As one of electronic gases, the purity of NF3 is very high. A fewpurification methods and equipments may be chosen according to differences inboiling point and physico-chemical properties of NF3 and its impurities. Afterweighing the advantages and disadvantages of methods such as cold trap, adsorptionand improved adsorption etc., a new purification process which is continuousdistillation in the low temperature was proposed, and with this method, we can obtainthe high pure production of NF3 gas which purity can meet the needs of electronicindustries.We expect that we can obtain the best process conditions through the distillationsimulation of continuous distillation in the low temperature to provide academic datafor lab experiment. By researching many distillation models and many calculationmethods, we find the appropriate distillation model to the NF3 system which ishomogeneous distillation model and the calculation method-equation dissociationmethod, and use state equation to calculate the state balance.We can obtain process parameter such as the tower plank number, refluenceratio, the feed-in plank etc of the distillation tower and variable like vapour rate,liquid rate, composition distributing etc by distillation simulation with thismethod. This method not only be applicable to this system, but also be the samewith other system which is sililar to this.