AVS 49th International Symposium
    Plasma Science Tuesday Sessions
       Session PS-TuP

Paper PS-TuP3
Ion Attachment Mass Spectrometer(IAMS) for in situ and Fragment-free Monitoring of Plasma-CVD and Dry-etching Processes

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Plasma Applications
Presenter: Y. Hirano, Anelva Corporation, Japan
Authors: Y. Hirano, Anelva Corporation, Japan
M. Nakamura, Anelva Corporation, Japan
Y. Shiokawa, Anelva Corporation, Japan
T. Fujii, Anelva Corporation, Japan
Correspondent: Click to Email
We have developed and commercialized Ion Attachment Mass Spectrometer (IAMS),@footnote 1@ which supplies mass spectra with no peaks due to fragment ions. Molecular ions are observed in spectra of even reactive molecules such as radicals. We demonstrated that IAMS enabled us to detect molecular ions of reactants of the Cu-CVD process and PFCs(perfluoro compounds) in an exhaust gas from a dry etching machine.@footnote 2@ However, our spectrometer shows the highest sensitivity at the sample pressure of 100 Pa so far and is hardly applicable to the in situ measurements of gases for etching or CVD whose pressure is less than 10 Pa; where signal intensity for the sample at a pressure of 1 Pa was roughly estimated to be 10,000 times smaller than at the pressure of 100 Pa. In this study, we have improved the IAMS as to show the satisfactory sensitivity for the sample with the pressure of 1 to 10 Pa by (1)decelerating primary ions before collision with sample molecules, and (2)improving efficiency of transportation of ions by using a specially designed ion lens system. As a result, the peak due to molecular ion for neat cyclo-C@sub 4@F@sub 8@ was observed at a pressure of 1 Pa where the signal intensity of 2X10@super -8@ A and S/N of 10@super 4@ were obtained at the SEM gain of 10,000. The low-Pressu re-IAMS has been found to be useful for in situ fragment-free monitoring of molecules and radicals, especially in plasma -CVD and dry etching processes. Precious discussions with Prof. Munetaka Nakata and Prof. Masao Takayanagi of Tokyo University of Agriculture and Technology are gratefully acknowledged. @FootnoteText@ @footnote 1@ T.Fujii, Mass Spectrometry Review 19(2000)111.@footnote 2@ M.Nakamura et al JVST-A 19(2001)110 5.