Ecr plasma source for gas abatement

Abstract

An apparatus is described as a source of a plasma with a variety of applications. Of particular interest is gas abatement whereby the toxic or environmentally harmful effluent from a process chamber is converted to harmless and stable products by passing through this plasma source. The plasma is produced in a gas by cooperation between a magnetic field of the proper strength and microwave energy of the proper frequency. The microwave field enters a chamber through a window of microwave transparent material to encounter a magnetic field formed by a permanent magnet placed on the opposite side of the chamber and designed such that the direction of propagation of the microwave field is parallel with the magnetic field lines in the center of the chamber. For the purpose of gas abatement the plasma source is located downstream from a processing chamber. The gas molecules in the effluent of the processing chamber are dissociated by electron impact collisions in the plasma, and suitable reaction partners for the molecular fragments are added either just before or just after passage through the plasma source. Plasma abatement is the ideal technology for treatment of industrial emissions of the very stable perfluorinated compounds used in the semiconductor industry for thin film etching and cleaning of chamber for chemical vapor deposition: CF.sub.4, C.sub.2 F.sub.6, and NF.sub.3. These compounds have been found to have extremely high global warming potential.