AVS 45th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS1-MoA

Paper PS1-MoA2
Point-of-Use Plasma Abatement of PFCs in a High Density Inductively Coupled Plasma

Monday, November 2, 1998, 2:20 pm, Room 314/315

Session: Environmental Issues and Emerging Technologies
Presenter: E.J. Tonnis, University of California, Berkeley
Authors: D.B. Graves, University of California, Berkeley
E.J. Tonnis, University of California, Berkeley
Correspondent: Click to Email
A current major environmental concern in semiconductor manufacturing involves the use and emission of PFCs (perfluorinated compounds) and HFCs (hydrofluorinated compounds) during plasma etching of silicon dioxide and plasma-assisted chamber cleaning processes in dielectric film CVD systems.@footnote 1@ While significant progress has been made recently in reducing the emissions of PFCs and HFCs from CVD tools using alternate chemistries and process optimization, the stringent demands on oxide etch process recipes has limited emission reduction progress for etch. A promising alternate strategy for reducing or eliminating these emissions in etch processes is via point-of-use (POU) plasma abatement systems. In this approach, a high density plasma is ignited between the turbomolecular pump and the mechanical backing pumps downstream of a plasma process emitting HFCs and/or PFCs. A flow of O@sub 2@ is added upstream of the POU abatement plasma which dissociates the PFC/HFC and O@sub 2@ mixture causing the CF@sub x@ fragments to react with O atoms to form products that can be removed downstream through caustic water scrubbing processes. We present experimental results indicating that a high density, inductively coupled RF plasma can abate a variety of pure PFCs, including CF@sub 4@, C@sub 2@F@sub 6@, and CHF@sub 3@ in the presence of O@sub 2@ by between 90% and 99%. In addition, recent abatement experiments conducted on the effluent of an industrial high density oxide etcher indicate that these high levels of abatement can be realized even in the presence of complex mixtures of etch products found in actual tool exhausts. Issues that may limit POU plasma abatement implementation into an industrial environment such as process contamination, particulate formation, and transient control of the abatement plasma have also been examined. @FootnoteText@ @footnote 1@The National Technology Roadmap for Semiconductors, Semiconductor Industry Association, pp. 154-157, 1997.