Mechanism of C4F8 dissociation in parallel-plate-type plasma

Abstract

To investigate the mechanism of C4F8 dissociation in parallel-plate-type plasma, we used several of the latest diagnostic tools and made extensive measurements of electrons, radicals, and ions under conditions that greatly suppressed the effects of plasma-surface interaction. These measurements showed that the amount of light fluorocarbon radicals and ions increased with increasing electron density. The dissociation of C4F8 was analyzed by using rate equations, after confirming the stability and uniformity of the plasma. The total dissociation rate coefficient of C4F8 was 1×10−8 cm3/s, and CF2 radicals were mainly generated from products of C4F8 dissociation. F was mainly generated from CF2 by electron-impact dissociation and lost by pumping. We could estimate that the C2F4 density was roughly comparable to the densities of CF and CF3, and that the surface loss probability of C2F4 increased with increasing electron density. C2F4 might play an important role in the etching because of its rich polymerization characteristics.

Low-energy electron collisions with tetrafluoroethene, C2F4

“…The triplet IVO wave function was used for all but the 1 1,3 A g pair of states, for which generating the singlet IVO was easier due to technical factors. Examination of the principal configurations in the corresponding SECI wave functions indicates that considering the singlet and triplet wave functions to be identical is a very good approximation for the 1,3 The elastic cross section was first computed at the staticexchange level of approximation. Further calculations incorporating polarization effects were then carried out for irreducible representations exhibiting prominent shape resonances, namely, 2 B 1u , 2 B 2g , and 2 B 2u .…”

“…3 Detailed understanding of the complex physical and chemical processes within a plasma reactor requires data describing the important collisional and reactive processes occurring both within the plasma and at the semiconductor surface. Among the many processes of interest, elastic and inelastic collisions between electrons and molecules of feed gas are particularly important, because such collisions are the principal mechanism of energy deposition, with the electrons serving to couple the applied fields to the internal and translational modes of the heavy particles and, simultaneously, to create reactive species.…”

Study for plasma etching of dielectric film in semiconductor device manufacturing. Review of ASET research project

“…These results indicate that the selectivity was governed by not only the absolute value of the F density or the ratio of [F]/[CFx], but also by the other form of deposition species. It is also found that the reduction of the F density in C 4 F 8 /Ar plasma was caused by the decrease in CF 2 density and not by a direct reaction of F with Si when the Si plate was irradiated by energetic ions [19,22].…”

“…Upon each electron impact, the molecule dissociates gradually into smaller radicals, i.e., multistep dissociation [19], such as,…”

Experimental Study of Capacitive RF c-C4F8 Discharge with Synchrotron Vacuum Ultraviolet Photoionization Mass Spectrometry

“…Hayashi et al studied the parallel-plate-type plasma of c-C 4 F 8 using several diagnostic tools including microwave interferometer, laser-induced fluorescence (LIF), infrared diode laser absorption spectroscopy (IRLAS), QMS, etc. [19]. Vasenkov et al [20] explored chemistry mechanism of the inductively coupled plasma of c-C 4 F 8 /Ar and c-C 4 F 8 /O 2 computationally and experimentally.…”