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 trifiuoromethane (CHF 3 ) with electrons in an effort to build a database on electronic and ionic collision processes that will aid the understanding of the behavior of CHF 3 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 CHF 3 into neutral species, electron-impact induced line and continuous light emission from CHF 3 , negative ion states of CHF 3 , 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 Besides some recent unpublished measurements of the total electron scattering cross section below 20 eV, to our knowledge no measurements are available of the cross sections of any of the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 trans-POlt, attachment,and ionization coefficients. While thc: available illfuHnatiull is meagta, 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.

Macromolecule formation in low density CF4 plasmas: The influence of H2

“…21 As such, the measured HFC in Eq. ͑2͒ will tend to underestimate the true conversion of CF 4 to CHF x in the plasma.…”

“…31 The reaction rate coefficients, k, for electron-induced reactions with the species listed in Table II were determined using electron impact cross sections, , recently reviewed by NIST and published in a series of reference monographs. [19][20][21]32,33 The electron energy distribution function is assumed to be Maxwellian about an average electron temperature T e for prediction of k…”

Vibrational excitations of CH4 by electron impact: a close-coupling treatment

“…The terms of the multipolar expansion of the interaction potential in equation 4were retained up to l 0,max , and the scattered wavefunction of the electron in equation 1was expanded, with the inclusion of the lowest two vibrational states n = 0 and 1, up to l max which yielded K-matrix elements converged within 1% (see figures 1 and 2). For the specific information on all the required parameters and properties for each of the vibrational modes which we study in this work, see table 3. In order to solve the close-coupling (CC) equations by means of standard Green function techniques, equation 2is rewritten as an integral equation (a Volterra equation: for details, see [30,31]).…”

Characteristic features of heterophase macromolecular chain reactions involving antioxidants in a non-crystalline polymer matrix

“…Also, for comparison with our mixture data, we have included Aschwanden's data for pure SF 6 [8][9][10], which show very clearly the limiting case and give further support to the fact that the electron drift velocity varies very weakly with the SF 6 content. The main reason for this behaviour may stem from the fact that CHF 3 is a highly polar molecule [11], with which the electrons interact very strongly, as is further evidenced in the inset of figure 1, where the dotted curve, pertaining to CHF 3 , almost overlaps with the other mixture curves [12,13].…”