Investigations of the structure of thin fluorocarbon films by x-ray diffraction and infrared spectroscopy

Abstract

The X‐ray diffraction method was tested for the investigation of the structure of thin fluorocarbon films grown in a glow discharge in tetrafluoroethylene. It could be shown that the computed electron densities are strongly related to the structure of the well known linear molecule of polytetrafluoroethylene. The results are supported by infrared absorption spectra. Foreign atoms and chain branching being a reason for the amorphous structure of the films were ascertained.

Fluorocarbon radicals and surface reactions in fluorocarbon high density etching plasma. II. H2 addition to electron cyclotron resonance plasma employing CHF3

“…Table I lists the chemical species and their corresponding positions in the assignments. 22,23 III. RESULTS Figure 1 shows the CF x (xϭ1 -3) radical and F atom densities together with the Ar emission intensity in the CHF 3 /H 2 plasma as a function of H 2 partial pressure, varied from 0 to 1.33 Pa, at a microwave power of 300 W and a CHF 3 pressure of 0.4 Pa. After exposing the chamber walls to CHF 3 /H 2 ͑50%͒ plasma at 300 W and 0.8 Pa for a few minutes, the CF x radical densities were measured with increasing H 2 partial pressure.…”

Plasma Polymerization of Fluorocarbons

“…Its assignment is not possible, though it may be assumed arising by chain distortions [74,75]. Both IR and FTIR (Fourier transform IR), when used in the normal transmission mode, give useful information on the bulk structure of the film, while the surface structure can be analyzed in the multiple internal reflection mode.…”

Surface Phenomena During Plasma-Assisted Atomic Layer Etching of SiO2

“…The presence of a small, sharp feature centered at ∼980 cm –1 is also attributed to vibrations in the CF x film. This peak was previously reported in plasma-deposited CF x films, and was attributed to CF 3 vibrations without assigning it to a specific normal mode. − However, according to most other reports, CF 3 stretching vibrations appear in the 1325–1365 cm –1 region, and the bending vibrations are below 800 cm –1 . − Regardless of the exact assignment for the ∼980 cm –1 mode in Figure a, this weak feature is characteristic of CF x films, and is not related to the SiF x ( x = 1, 2, 3) stretching vibrations that appear at ∼960 cm –1 . ,,, The spectra in red in Figure a show the removal of the CF x film through 20-s intervals of Ar plasma for a total of 140 s. The CF x film shown in blue was the reference spectrum for each spectrum in red in Figure a. Thus, a decrease in absorbance indicates the removal of a particular species from the film during the Ar + bombardment.…”

“…However, in Figure 4a, two additional weak absorption features appear in the spectrum for the 21.4 Å CF x film that are related to deposition onto SiO 2 as compared to deposition onto the bare ZnSe IRC: a small shoulder at ∼1110 cm −1 , which corresponds to C−O−Si stretching vibrations, and a weak broad peak from ∼950−990 cm −1 , which corresponds to the stretching vibrations for SiF x (x = 1, 2, 3) species as well as some contribution from the CF x film. [31][32][33][34][35][36][37]41,42,46 Figure 4b compares the line shape in the ∼900−1000 cm −1 region based on the underlying film, which is either the bare ZnSe IRC or the SiO 2 film on the ZnSe IRC. The peak centered at ∼980 cm −1 is due to the CF x film, and is evident in both spectra in Figure 4b.…”