Process and system for separation and recovery of perfluorocompound gases

A process to recover at least one perfluorocompound gas or gas mixture from a gas mixture flowing from a semiconductor manufacturing process, comprising the steps of:

• a) providing a first gas mixture comprising at least one perfluorocompound gas, at least one species harmful to a polymer membrane, and at least one carrier gas;
• b) providing said polymer membrane having a feed side and a permeate side;
• c) pretreating said first gas mixture to reduce the concentration of said species harmful to said polymer membrane and obtaining a treated gas mixture;
• d) contacting the feed side of said polymer membrane with said treated gas mixture;
• e) withdrawing a concentrated gas mixture comprising a higher concentration of the at least one perfluorocompound gas than in the treated gas mixture, from the feed side of the polymer membrane as a non-permeate stream at a pressure which is substantially equal to a pressure of said gas mixture;
• and
• f) withdrawing a permeate gas mixture from the permeate side of said polymer membrane, said permeate gas mixture enriched in carrier gas.

A semiconductor manufacturing system comprising:

• a) at least one reactor chamber adapted to receive a gas mixture comprising perfluorocompound gases, and carrier gases, the reactor chamber having a reactor effluent gas conduit attached thereto;
• b) compression means located in the reactor effluent conduit to compress an effluent gas from the reactor chamber,
• c) at least one membrane separation unit having a feed side and a permeate side, said membrane being permeable to at least one carrier gas and being substantially non-permeable to at least one perfluorocompound gas, said membrane unit connected to said reactor chamber via the reactor effluent conduit downstream of the compression means, said membrane unit having a permeate vent conduit and a non-permeate conduit, and said membrane having a selectivity ratio, "SEL," greater than about 1.0 for any of said at least one carrier gas relative to any of said at least one perfluorocompound gas
• wherein,
• SEL=›D.sub.c !›S.sub.c !/›D.sub.p !›S.sub.p !
• wherein,
• SEL is the selectivity ratio
• D.sub.p is the mobility selectivity of a perfluoro compound gas
• S.sub.p is the solubility selectivity of the perfluoro compound gas
• D.sub.c is the mobility selectivity of a carrier gas
• S.sub.c is the solubility selectivity of the carrier gas
• d) means to recycle at least a portion of a non-permeate stream from said membrane unit back to the at least one reactor chamber;
• e) pretreatment means in flow communication with the reactor effluent stream-entering and the membrane unit, said pretreatment means selected from the group consisting of plasma decomposition, thermal decomposition, catalytic removal, scrubbing, and adsorption;
• f) the membrane unit comprising a sweep gas conduit in flow communication with the non-permeate conduit and the permeate side of the membrane;
• g) a damper or surge tank in flow communication with the non-permeate conduit;
• and
• h) a compressor, heat exchanger, cryogenic pump or vacuum pump in flow communication with the non-permeate conduit upstream of the surge tank, allowing a perfluorocarbon enriched stream to be stored in liquid form for future use.

A system for recovering a perfluorocompound gas from a gas mixture, the system comprising:

• a) treatment means for creating a treated gas mixture suitable for compression,
• b) a compressor for compressing the treated gas mixture to form a compressed gas mixture;
• and
• c) at least one glassy polymer membrane separation unit having a feed side and a permeate side, said membrane being permeable to at least one carrier gas and being substantially non-permeable to at least one perfluorocompound gas, said membrane unit connected to said compressor via a conduit, said membrane unit having a permeate vent conduit and a non-permeate conduit.

A system for recovering a perfluorocompound gas, the system comprising:

• a) compression means adapted to compress a gas mixture containing a carrier gas and a perfluorocompound gas;
• b) at least one size selective membrane separation unit having a feed side and a permeate side, said membrane being preferentially permeable to at least one carrier gas and being substantially non-permeable to at least one perfluorocompound gas, said membrane unit in flow communication with said compression means, a permeate vent conduit and a non-permeate conduit,
• c) means to recycle at least a portion of a non-permeate stream from said membrane unit back to a source of said gas mixture;
• d) gas treatment means positioned prior to the gas mixture entering the membrane unit, said gas treatment means selected from the group consisting of plasma decomposition, thermal decomposition, catalytic removal, scrubbing, and adsorption;
• e) the membrane unit comprising a sweep gas conduit in flow communication with the nonpermeate conduit and the permeate side of the membrane,
• f) a damper or surge tank in flow communication with the non-permeate conduit;
• g) liquefying means selected from the group consisting of a compressor, heat exchanger, cryogenic pump and a vacuum pump, in flow communication with the non-permeate conduit, allowing a perfluorocarbon enriched stream to be stored in condensed form for future use.