The dissociative recombination of CF⁺₃

Abstract

The dissociative recombination rate coefficient for CF + 3 has been measured at 300 K using a flowing afterglow Langmuir probe-mass spectrometer (FALP-MS) apparatus. A value of (2.8 ± 0.8) × 10 −7 cm 3 s −1 has been found. This is about a factor of 3 less than values for this reaction, commonly used in plasma models.

The dissociative recombination of fluorocarbon ions III: CF+2and CF+3

“…For the production of CF radical, the ionization of CF 4 followed by recombination competes directly with the electron impact dissociation of CF 4 , whose cross section is of the same order of magnitude as that for the ionization of CF 4 [1 ]. Indeed, experimental studies by Sugai and co-workers [30,31] indicate that the channel leading to CF from the electron impact dissociation of CF 4 accounts for only about 15% of the total rate and that leading to CF 2 only about 10%. Hence, dissociative ionization followed by recombination must be considered the major route for the formation of CF and CF 2 radicals in etching plasmas.…”

“…We have recently, however, published cross sections for the ion CF + [3] measured using the ASTRID and CRYRING storage rings. A flowing afterglow Langmuir probe-mass spectrometer (FALP-MS) measurement of the rate coefficient of the recombination of CF + 3 at 300 K has also been published [4]. In this paper, we have continued this study with storage ring investigations of the cross sections and branching ratios for the dissociative recombination of CF + 2 and CF + 3 .…”

“…Compilations of cross sections and rate coefficients for the many and varied reactions that occur in a CF 4 plasma have been given by Christophorou and co-workers [1,2], but until recently there was no information concerning certain reactions, in particular that of the dissociative recombination of ions formed in the CF 4 plasma. We have recently, however, published cross sections for the ion CF÷ [3] measured using the ASTRID and CRYRING storage rings.…”

“…For these two ions, the following dissociation channels are energetically allowed at zero relative energy, assuming that the parents and products are in their ground states. All energies are calculated using data from the NIST Webbook [5], except for the value of the CF•3 heat of formation, which is deduced from the appearance energy of CF•3 from CF 4 [6]:…”

The dissociative recombination of fluorocarbon ions: II. CF+

“…Fluorocarbon radicals and ions are observed in fluorocarbon plasmas used for semiconductor processing and in flames following the introduction of fluorinated extinguishing agents. In a previous publication [1] (hereafter paper I in this series), we have reported a measurement of the rate coefficient for the dissociative recombination of CF 3 + , performed using a flowing afterglow Langmuir probe-mass spectrometer (FALP-MS) apparatus. In this second paper,…”