Investigation of gas phase chemistry of alkylsilane molecules in a hot wire chemical vapor deposition reactor

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dc.contributor.advisorShi, Yujun
dc.contributor.authorLi, Xinmao
dc.date.accessioned2017-12-18T21:27:28Z
dc.date.available2017-12-18T21:27:28Z
dc.date.issued2007
dc.descriptionBibliography: p. 125-133en
dc.descriptionSome pages are in colour.en
dc.description.abstractHot-wire chemical vapor deposition (HWCVD) is a new and promising technique to fabricate device quality thin films. It is believed that gas-phase reactions play an important role in the deposition of high quality films. In this work, three alkylsilane molecules, namely tetramethylsilane (TMS), trimethylsilane, and hexamethyldisilane (HMDS), were used as single source gases in a HWCVD reactor for SiC film deposition. 118 nm vacuum ultraviolet (VUV) laser single photon ionization (SPI) coupled with time-of-flight (TOF) mass spectrometry were used to study the decomposition products of all three molecules on the hot filament made of tungsten or tantalum under collisionfree conditions and subsequent gas-phase reaction products formed in a HWCVD reactor. It is found that alkylsilane molecules decompose to radicals on the hot filament. Methyl radicals are produced from all three molecules studied. Hydrogen abstraction reactions between the methyl radical and the abundant parent molecules produce more radicals in the HWCVD reactor. Subsequent biradical combination reactions constitute the main secondary gas-phase reaction pathways, resulting in the formation of many alkylsubstituted silanes and silyl-substituted alkanes. In addition, it is believed that several disilacyclobutane compounds have been produced through the cycloaddition of the unsaturated silene intermediates. This provides strong evidence for the existence of the reactive silene species in the reactor. The Si-C bond is found to be the major bond connection in the gas phase reaction products. With Si-Si bonds in HMDS and Si-H bonds in trimethylsilane, more Si-Si bond connections are present in the backbone of the high mass reaction products. Due to the existence of both Si-Hand C-H bonds in trimethylsilane, experiments with its isotopomer, (CH3) 3 SiD, have demonstrated that two H-abstraction reactions exist between CH3 radical and the parent molecule, yielding two secondary radicals with the same mass. This leads to the observation that trimethylsilane has the most complicated gas phase chemistry of the three molecules studied. A study of the effect of TMS partial pressure has shown that source gas decomposition on the filament and secondary gas-phase reactions become less efficient with a decrease in the source gas pressure in the reactor. The experiments with TMS using both W and Ta filaments indicate that the filament material does not affect the decomposition pathway of source gas on the filament. Results with a 0.25% TMS in He mixture suggest that Ta may have a slightly better catalytic capability than W in decomposing TMS.
dc.format.extentxiv, 133 leaves : ill. ; 30 cm.en
dc.identifier.citationLi, X. (2007). Investigation of gas phase chemistry of alkylsilane molecules in a hot wire chemical vapor deposition reactor (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/1401en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/1401
dc.identifier.urihttp://hdl.handle.net/1880/102402
dc.language.isoeng
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.titleInvestigation of gas phase chemistry of alkylsilane molecules in a hot wire chemical vapor deposition reactor
dc.typemaster thesis
thesis.degree.disciplineChemistry
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameMaster of Science (MSc)
ucalgary.item.requestcopytrue
ucalgary.thesis.accessionTheses Collection 58.002:Box 1731 520492248
ucalgary.thesis.notesUARCen
ucalgary.thesis.uarcreleaseyen
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