In situ analysis of perfluoro compounds in semiconductor process exhaust: Use of Li+ ion-attachment mass spectrometry

Ion-attachment mass spectrometry is capable of accurate and in situ analysis of multicomponent gases that may even include unknown components. We developed a compact apparatus that uses this method and examined its performance for perfluoro compounds, a class of greenhouse gases, using typical standard gases, and subsequently applied the method to the in situ analysis of exhaust gases from a dry-etching machine, where c-C4F8/O2/Ar plasma is generated. Perfluoro compounds of low concentration can be detected as quasimolecules without any fragmentation. In the exhaust gases, many components that are not considered in the current measurement protocol [J. Meyers, D. Green, P. Maroulis, and W. Reagen, Equipment Environmental Characterization Guidelines, Rev. 3.0 (INTEL, 1999)] are measured, as well as components already reported.

[1]  Fujii,et al.  Alkali-metal ion/molecule association reactions and their applications to mass spectrometry , 2000, Mass spectrometry reviews.

[2]  Matsushita,et al.  Electric field assisted thermal desorption ionization using an infrared laser. , 1999, Rapid communications in mass spectrometry : RCM.

[3]  L. Zazzera,et al.  Infrared Study of Process Emissions during C 3 F 8 / O 2 Plasma Cleaning of Plasma Enhanced Chemical Vapor Deposition Chambers , 1997 .

[4]  T. Fujii,et al.  Filament thermionic sources of Li+ ions in low heating power , 1995 .

[5]  Fujii,et al.  Production of large O-containing neutral hydrocarbon species by a CH4-O2 microwave discharge. , 1994, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[6]  T. Fujii,et al.  Mass spectrometric studies of the neutral and ionic products in a methane/oxygen microwave discharge plasma , 1993 .

[7]  J. Forster,et al.  Novel radio‐frequency induction plasma processing techniques , 1993 .

[8]  T. Fujii,et al.  Mass spectrometric detection of neutral radicals in a CH4 microwave discharge by use of Li+ ion attachment techniques , 1993 .

[9]  Fujii,et al.  Identification of intermediate radicals in the CH4 microwave plasma by the Li+ attachment method. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[10]  P. P. Ong,et al.  Characteristics of aluminosilicates as thermionic sources of Na+ and K+ ions , 1992 .

[11]  T. Fujii.  Quadrupole mass spectrometry in combination with lithium ion attachment for sampling at atmospheric pressure: possible coupling to supercritical fluid chromatography , 1992 .

[12]  T. Fujii.  A novel method for detection of radical species in the gas phase: usage of Li+ ion attachment to chemical species , 1992 .

[13]  T. Fujii,et al.  Chemical ionization mass spectrometry with lithium ion attachment to the molecule , 1989 .

[14]  J. Allison,et al.  Potassium ion chemical ionization and other uses of an alkali thermionic emitter in mass spectrometry , 1984 .

[15]  J. Beauchamp,et al.  Application of alkali ions in chemical ionization mass spectrometry , 1976 .

[16]  A. Good.  Third order ion-molecule clustering reactions , 1975 .

[17]  J. Beauchamp,et al.  Intrinsic acid-base properties of molecules. Binding energies of lithium(1+) ion to .pi.- and n-donor bases , 1975 .

[18]  H. Schulten,et al.  Molecular weight determination by cationisation , 1975 .

[19]  E. Ferguson,et al.  Termolecular and saturated termolecular kinetics for Li + and F - , 1973 .

[20]  E. J. Jones,et al.  Filament Sources of Positive Ions , 1936 .