Electron Interactions with CHF3

Abstract

In this paper we assess and synthesize the available information on the cross sections and the rate coefficients for collisional interactions of trifluoromethane (CHF3) with electrons in an effort to build a database on electronic and ionic collision processes that will aid the understanding of the behavior of CHF3 in its use in manufacturing semiconductor devices and other applications. The limited data on the total and partial electron impact ionization cross sections, total and partial cross sections for electron impact dissociation of CHF3 into neutral species, electron-impact induced line and continuous light emission from CHF3, negative ion states of CHF3, and the energetics of ionization, dissociation, and attachment are summarized and discussed. Besides some recent unpublished measurements of the total electron scattering cross section below 20 eV, to our knowledge no measurements are available of the cross sections of any of the electron scattering processes (elastic, momentum, vibrational, inelastic, etc.) or the electron transport, attachment, and ionization coefficients. While the available information is meager, the synthesis of the existing knowledge and the background information provided in the paper can be helpful for modeling plasma reactors. Clearly, more measurements and calculations are needed of the cross sections for virtually all fundamental electron impact processes for this plasma processing gas. Measurements of the transport, attachment, and ionization coefficients over wide ranges of the density reduced electric field are also needed.