Mechanism of amorphous silica film formation from tetraethoxysilane in atomic oxygen-induced chemical vapor deposition
In: Journal of the Electrochemical Society, Jg. 145 (1998), Heft 8, S. 2866-2876
academicJournal
- print, 58 ref
Zugriff:
Atomic oxygen-induced chemical vapor deposition (AOCVD), using tetraethoxysilane (TEOS) as single-source compound, was investigated to get insight into the mechanism of silica film growth. In particular, an effort was made to elucidate the chemical nature of silica film-forming precursors. AOCVD, selected as a model process suitable for mechanistic study, has been examined in terms of the effects of atomic oxygen concentration, of the contents of the ground and excited state oxygen atoms in atomic oxygen fraction, and of thermal activation. The growth rate of silica film does not depend on the composition of the atomic oxygen fraction, but is proportional to the total concentration of atomic oxygen fed into the CVD reactor. In the light of the apparent activation energy (Ea) values calculated from the Arrhenius plots of the substrate temperature dependencies of film growth rate, the mechanism of AOCVD is related to the concentration of atomic oxygen. The near zero Ea value found at low concentration of atomic oxygen (1.5 × 101 cm-3) implies that AOCVD is not a thermally activated process; diffusion of the precursors from the gas phase to the substrate seems to be the ratelimiting factor of AOCVD under these conditions. Apparently negative Ea values observed for high concentrations of atomic oxygen(≥9.7 × 1014 cm-3) indicate that the adsorption of the precursors onto the growth surface is the main factor controlling the rate of AOCVD. Reaction products of the gas-phase conversion of TEOS, investigated by high-resolution gas chromatography/mass spectrometry, revealed the presence of linear and cyclic siloxane oligomers, containing the -(EtO)2SiO- repeating unit. The structure O identified oligomers, results of the study of TEOS reactions with atomic oxygen, the structure of the deposited film, chemiluminescence spectra of the gas-phase products in the CVD reactor, and the results of step coverage tests, point to diethoxysilanone (a high reactivity intermediate) and hexaethoxydisiloxane (a high surface mobility, low reactivity intermediate) as the major precursors of silica film growth.
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Mechanism of amorphous silica film formation from tetraethoxysilane in atomic oxygen-induced chemical vapor deposition
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Autor/in / Beteiligte Person: | WROBEL, A. M ; WALKIEWICZ-PIETRZYKOWSKA, A ; WICKRAMANAYAKA, S ; HATANAKA, Y |
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Zeitschrift: | Journal of the Electrochemical Society, Jg. 145 (1998), Heft 8, S. 2866-2876 |
Veröffentlichung: | Pennington, NJ: Electrochemical Society, 1998 |
Medientyp: | academicJournal |
Umfang: | print, 58 ref |
ISSN: | 0013-4651 (print) |
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