Low-temperature deposition of silicon dioxide films from electron cyclotron resonant microwave plasmas

Abstract

Silicon dioxide films were deposited on crystalline silicon substrates by electron cyclotron resonant (ECR) microwave plasma-enhanced chemical vapor deposition (PECVD). Films were grown on Si〈100〉 substrates at temperatures of 140–600 °C, flow rates of 0.5–10 sccm SiH4, 10–30 sccm O2, and at a pressure of 10−3 Torr. Infrared absorption spectroscopy of the samples indicated no detectable SiH, OH, or SiOH groups. Neither an afterglow chemistry nor He dilution was required to eliminate H impurities as was previously reported for silicon oxide films deposited from rf plasmas. This suggests that significant differences exist between rf and ECR microwave plasma chemistries. We have found that the stoichiometry and index of refraction was not sensitive to oxidant ratio for a wide range of conditions in contrast to other studies. Stoichiometric SiO2 films, with good physical properties, were grown for a much wider range of oxidant ratios relative to those which are characteristic of the rf PECVD technique. In addition, films grown under optimal conditions had infrared absorption spectra nearly identical to those of thermally grown oxides and index of refraction of 1.456, as measured by ellipsometry. We concluded that by using an ECR microwave plasma, SiO2 films with optical and bonding properties comparable to oxides thermally grown at 1000 °C in dry oxygen can be deposited at a low temperature (350 °C) and a low pressure (10−3 Torr) in a O2/SiH4 reactant gas mixture without the need for a carrier gas.

Analysis of transport phenomena during plasma deposition of hydrophobic coatings on porous cellulosic substrates in plane‐to‐plane dielectric barrier discharges at atmospheric pressure

“…Rather than composition modifications, shifting to higher wavenumbers can be correlated to a more open and less dense structure. [ 48,49 ] In parallel with the decrease in the intensity of bands corresponding to the coating from the entrance to the exit, the area under the wide regions between 3,000 and 3,700 cm −1 (OH stretching), 1,772 and 1,534 cm −1 (OH bending), and 750 and 500 cm −1 (C–C bonding), which contain the cellulose characteristic peaks, increases. According to the Beer–Lambert law, in absorbance or transmittance FTIR measurements, the intensity of the peak scales with transition dipole moment and bond density, which in abstract can be called “concentration.” [ 50 ] As a result, according to the changes in the intensity and position of different peaks in the spectra, it can be concluded that there is a change in chemical concentration of the coating between the entrance and the exit (Figure 5b).…”

Fabrication and characterisation of thin low-temperature MBE-compatible silicon oxides of different stoichiometry

“…The background was subtracted from the Si 2p peak. Five symmetric Gaussian bands representing the different valence states Si, Si 1 , Si 21 , Si 31 and Si 41 were added with the maximum at binding energies of 99.4, 100.3, 101.3, 102.2, and 103.4 eV with a tolerance of 0.2 eV. The FWHM was ®xed to 1:4^0:2 eV for all states except for the Si 41 subband where 1:7^0:2 eV was used.…”

Spectroscopy of silicon dioxide films grown under negative corona stress

“…3 and lower to that obtained on ECR deposited SiO 2 films. 4 The high frequency shoulder is often associated with stoichiometry of the film. As the oxide moves off xϭ2 in SiO xϭ2 , the shoulder becomes less sharp and merges with the main stretching absorption band.…”

“…A broad shoulder at 1150 cm Ϫ1 was also observed. The extra peak is attributed to the presence of SiO 4 2Ϫ ions and could be the outcome of incomplete oxidation at the surface. The films indicated properties similar to a fully relaxed thermally grown silicon dioxide film with a contradictory nature.…”