Mass Spectrometry for On-Line Monitoring of Perfluoro Compounds Using Li⁺ Ion Attachment Techniques

Abstract

Ion attachment mass spectrometry is being developed for continuous measurement of perfluoro compounds (PFCs) found in the atmosphere as a result of semiconductor manufacturing processes. Studies were made on 5 greenhouse gases, CF4, CHF3, C2F6, SF6, and c-C4F8, to develop improved methods for PFC analysis, particularly at levels found in the atmosphere (the parts-per-billion concentration range). The results demonstrate the feasibility of performing real-time measurements of the trace amounts of PFCs encountered in process facilities by generating adduct ions from Li+ ion attachment. The identification and detection of c-C4F8 is described as an example of the utility of this new method.

Mass spectrometric investigation and formation mechanisms of high-mass species in the downstream region of Ar/CF4/O2plasmas

“…It is fragment-free in most cases and allows us to observe even neutral saturated straight-chain PFCs as their Li + adducts in mass spectrometry. 6,7 Using this technique, we have recently found that various neutral molecules, as well as positive ions with mass numbers as high as 400 amu (where the maximum mass number is determined by the limitations of our mass spectrometer), are present in the downstream region of Ar/CF 4 plasmas. 8 In addition, we have clarified the growth mechanism of their high-mass positive ions.…”

Evaluation Method on Destruction and Removal Efficiency of Perfluorocompounds from Semiconductor and Display Manufacturing

“…This assumption does not significantly affect the calculation of the flow rate according to the following Eq. (9)- (15).…”

“…In general, the scrubber efficiency is obtained by on-line based on Fourier Transform Infrared Spectroscopy (FTIR) 13,14 or real time Quadrupole Mass Spectrometry (QMS) method. 15,16 Under these methods, the PFC amount has to be calculated considering the flow rate, pressure, and temperature at inlet and outlet of the scrubber. 13,17 Here, we suggest a reliable method to obtain the efficiencies of various scrubbers in accordance with the guidelines by the IPCC.…”

Observation of NOx species in a N2/O2/H2O microwave discharge plasma: A laboratory simulation of Earth's atmosphere

“…The apparatus was essentially the same as that used previously in a number of other studies of the free radicals formed in MW discharge plasmas [ Fujii , 2000; Selvin and Fujii , 2001; Fujii et al , 2001]. Briefly the apparatus consists of a 15‐cm flow tube, combined with a Li + ion attachment mass spectrometer (Anelva Corp., Tokyo, Japan), and the products (M) were detected and assigned as their lithium adducts (M + Li) + .…”

“…The recently developed Li + ion attachment mass spectrometry (Li + MS) technique provides mass spectra of quasi‐molecular ions formed by lithium ion attachment to chemical species under high pressure [ Fujii , 2000; Selvin and Fujii , 2001; Fujii et al , 2001]. Results are obtained in the form of mass spectrometric traces of Li + adducts.…”