IR Absorption Spectra of SiO2 Films Grown by Photo-CVD

Ashokan, R.; Gopal, Vishnu; Chhabra, K.C.

doi:10.1002/pssa.2211210223

Cited by 7 publications

(1 citation statement)

References 21 publications

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“…Both peak maxima show minor frequency shifts of a few wavenumbers as a function of the layer thickness and also between the different precursors, but the overall shape of this band remains essentially unchanged from the native oxide layer (spectra (0/0) up to 23 deposited SiO 2 layers (spectra 23/23), regardless of the particular precursor. Since the ν(SiO) peak shape and frequency are known to respond very sensitively to changes in the composition and structure of the SiO 2 film, it may be concluded that this deposition process produces amorphous, “native-like” silicon oxide regardless of the type and structure of the alkylsiloxane precursor film. The ν(SiO) band intensities in Figure , therefore, lack any specific structural or orientational contributions (contrary to the ν(CH) intensities, for example) and can be used as a second, independent measurein addition to the ellipsometric data of Figure for the thickness of the oxide film.…”

Section: Resultsmentioning

confidence: 99%

Monolayer-Controlled Deposition of Silicon Oxide Films on Gold, Silicon, and Mica Substrates by Room-Temperature Adsorption and Oxidation of Alkylsiloxane Monolayers

Vallant¹,

Brunner²,

Kattner³

et al. 2000

J. Phys. Chem. B

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Ultrathin SiO 2 films with thicknesses between 0.3 and 8 nm were grown on native silicon (Si/SiO 2 ), muscovite mica and polycrystalline gold substrates via repeated application of a binary reaction sequence, which involved the formation of a self-assembled alkylsiloxane monolayer (step A) and UV-ozone oxidation of the hydrocarbon groups (step B). Using octadecyltrichlorosilane as a precursor, SiO 2 films could be grown in a strictly linear, layer-by-layer mode on each of the three substrates with a growth rate of 3.0 ( 0.3 Å per deposition cycle, which corresponds to a monolayer of SiO 2 . The properties of these oxide films (composition, structure, packing density) were found to be essentially identical and independent of the substrate, as evidenced by ellipsometry, infrared reflection, and X-ray photoelectron spectroscopy. Furthermore, the quality of the oxide layers was investigated as a function of the hydrocarbon chain length of the alkylsiloxane monolayer formed in step A, using four different alkyltrichlorosilanes, R-SiCl 3 (R ) C 18 H 37 , C 11 H 23 , C 4 H 9 , CH 3 ), as precursors. For each compound, a linear increase of the SiO 2 film thickness with the number of applied deposition cycles was again observed, but the growth rate increased noticeably from 2.8 Å/cycle for the C 18 and the C 11 compound to 3.2 Å/cycle and 6.5 Å/cycle for the C 4 and the C 1 compound, respectively, concomitant with an increase of the surface roughness in atomic force microscopy images of the oxide films. The packing density of the Si atoms in these films remains essentially constant for longer-chain precursors (R g C 4 ), although the structure of the hydrocarbon layer changes drastically from a highly-ordered, perpendicular alignment on the surface (R ) C 18 ) to a random, isotropic arrangement (R e C 11 ). For films prepared from shorter precursors (R < C 4 ), however, multilayer formation sets in and results in film growth rates clearly beyond the monolayer level. A minimum chain length of about four C atoms is therefore required to restrict the alkylsiloxane film formation (step A) to the monolayer level and to provide reproducible and precise control of the oxide film thickness in this deposition process.

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Section: Resultsmentioning

confidence: 99%

Monolayer-Controlled Deposition of Silicon Oxide Films on Gold, Silicon, and Mica Substrates by Room-Temperature Adsorption and Oxidation of Alkylsiloxane Monolayers

Vallant¹,

Brunner²,

Kattner³

et al. 2000

J. Phys. Chem. B

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Photo-induced chemical vapour deposition of silicon oxide thin films

et al. 1992

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Structural characterization of photochemically grown silicon dioxide films by ellipsometry and infrared studies

Ashokan

Singh

Gopal

et al. 1993

Journal of Applied Physics

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Silicon dioxide films grown by photochemical vapor deposition at different deposition rates are investigated by ellipsometry and Fourier transform infrared measurements. Disagreement in the variation of refractive index with chamber pressure between thin and thick films is interpreted in terms of a deposition rate dependent buildup of internal stress in the film. Direct measurements of curvature show the presence of compressive stress in thick SiO2 films grown at chamber pressures ≳600 mTorr. Infrared transmission measurements also indicate a change in the structural characteristics of films (probably induced by stress), with increasing deposition rate. Molecular model calculations show a decrease in the Si—O—Si bond angle as the growth pressure increases. Ion implantation seems to release the stress in these films as evidenced by the shift observed in the stretching mode frequency. The relative concentrations of H2O, SiOH, and SiH groups in these films and the effect of annealing on the strength of these modes are also discussed. Reflection infrared measurements at 60° incidence reveal a disorder induced longitudinal-transverse optic pair at around 1200 cm−1.

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IR Absorption Spectra of SiO2 Films Grown by Photo-CVD

Cited by 7 publications

References 21 publications

Monolayer-Controlled Deposition of Silicon Oxide Films on Gold, Silicon, and Mica Substrates by Room-Temperature Adsorption and Oxidation of Alkylsiloxane Monolayers

Monolayer-Controlled Deposition of Silicon Oxide Films on Gold, Silicon, and Mica Substrates by Room-Temperature Adsorption and Oxidation of Alkylsiloxane Monolayers

Photo-induced chemical vapour deposition of silicon oxide thin films

Structural characterization of photochemically grown silicon dioxide films by ellipsometry and infrared studies

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