Process for purifying nitrogen trifluoride gas
CA 1316330 C · Owner: Mitsui Toatsu Chemicals, Inc. · Inventors: Nishitsuji, Toshihiko; Harada, Isao; Iwanaga, Naruyuki
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process is provided herein for obtaining a high purity nitrogen trifluoride gas containing at least oxygen difluoride which is used as a dry etching agent for semiconductors or a cleaning gas for CVD apparatus, etc. The process comprises removing hydrogen fluoride to 100 ppm or less in the nitrogen trifluoride gas and then contacting the nitrogen trifluoride gas with at least one aqueous solution containing a component selected from the group consisting of sodium thiosulfate hydrogen iodide and sodium sulfide to remove oxygen difluoride.
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted April 20, 1993. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended April 20, 2010.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.