@article{chambers_busch_schulte_gustafsson_garfunkel_wang_maher_klein_parsons_2001, title={Effects of surface pretreatments on interface structure during formation of ultra-thin yttrium silicate dielectric films on silicon}, volume={181}, ISSN={["0169-4332"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000171063300009&KeyUID=WOS:000171063300009}, DOI={10.1016/S0169-4332(01)00373-7}, abstractNote={X-ray photoelectron spectroscopy (XPS) and medium energy ion scattering (MEIS) are used to determine chemical bonding and composition of ultra-thin films of mixed yttrium, silicon, and oxygen, formed by oxidation of metal on clean and pre-treated silicon. XPS and MEIS analyses indicate that oxidation of yttrium on bare silicon results in a fully oxidized film with a significant fraction of Y–O–Si bonding. The mixed Y–O–Si structure results from the relatively rapid reaction between Y and the Si substrate to form yttrium silicide, followed by oxidation. The effect of various silicon pretreatments, including in situ oxidation and nitridation, on bulk and interface film composition are also examined. Transmission electron microscopy (TEM) of 40 Å thick films indicates that the yttrium silicate films are amorphous with uniform contrast throughout the layer. MEIS shows evidence for a graded metal concentration in the dielectric near the silicon interface, with uniform oxygen concentration (consistent with full oxidation) throughout the film. Angle resolved XPS (ARXPS) shows no significant signal related to Si+4, as would be expected from a substantial SiO2 interface layer. Capacitance–voltage analysis demonstrates that a ∼10 Å equivalent oxide thickness can be achieved. The effects of ultra-thin silicon oxide, nitrided-oxide and nitrided silicon interfaces on silicon consumption during the oxidation of yttrium are investigated. When yttrium is deposited on a thin (∼10 Å) SiO2 film and oxidized, a yttrium silicate film is formed with bonding and composition similar to films formed on bare silicon. However, when the interface is a thin nitride, the silicon consumption rate is significantly reduced, and the resulting film composition is closer to Y2O3. The consumption of the silicon substrate by metal is shown to occur during oxidation and during vacuum annealing of yttrium on silicon. The relatively rapid formation of metal–silicon bonds suggests that metal–silicon structures may also be important reactive intermediates in silicon/dielectric interface formation reactions during chemical vapor deposition. In addition to thermodynamic stability, understanding the relative rates of elementary reaction steps in film formation is critical to control composition and structure at the dielectric/Si interface.}, number={1-2}, journal={APPLIED SURFACE SCIENCE}, author={Chambers, JJ and Busch, BW and Schulte, WH and Gustafsson, T and Garfunkel, E and Wang, S and Maher, DM and Klein, TM and Parsons, GN}, year={2001}, month={Sep}, pages={78–93} }
 @article{klein_niu_epling_li_maher_hobbs_hegde_baumvol_parsons_1999, title={Evidence of aluminum silicate formation during chemical vapor deposition of amorphous Al2O3 thin films on Si(100)}, volume={75}, ISSN={["0003-6951"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000084242700033&KeyUID=WOS:000084242700033}, DOI={10.1063/1.125519}, abstractNote={Using narrow nuclear reaction resonance profiling, aluminum profiles are obtained in ∼3.5 nm Al2O3 films deposited by low temperature (<400 °C) chemical vapor deposition on Si(100). Narrow nuclear resonance and Auger depth profiles show similar Al profiles for thicker (∼18 nm) films. The Al profile obtained on the thin film is consistent with a thin aluminum silicate layer, consisting of Al–O–Si bond units, between the silicon and Al2O3 layer. Transmission electron microscopy shows evidence for a two-layer structure in Si/Al2O3/Al stacks, and x-ray photoelectron spectroscopy shows a peak in the Si 2p region near 102 eV, consistent with Al–O–Si units. The silicate layer is speculated to result from reactions between silicon and hydroxyl groups formed on the surface during oxidation of the adsorbed precursor.}, number={25}, journal={APPLIED PHYSICS LETTERS}, author={Klein, TM and Niu, D and Epling, WS and Li, W and Maher, DM and Hobbs, CC and Hegde, RI and Baumvol, IJR and Parsons, GN}, year={1999}, month={Dec}, pages={4001–4003} }
 @article{klein_anderson_chowdhury_parsons_1999, title={Hydrogenated silicon nitride thin films deposited between 50 and 250 degrees C using nitrogen/silane mixtures with helium dilution}, volume={17}, ISSN={["0734-2101"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000078136300017&KeyUID=WOS:000078136300017}, DOI={10.1116/1.582104}, abstractNote={Silicon nitride thin films, deposited by plasma enhanced chemical vapor deposition at temperatures between 250 and 50 °C from SiH4, N2 and He, were characterized using transmission infrared spectroscopy, ellipsometry, wet etch rate, and current-voltage analysis. At 250 °C using SiH4/N2/He flow ratios of 1/150/75, films with refractive index=1.80 and H concentrations <20%, distributed equally in Si-H and N-H units were obtained. The concentration of hydrogen and its distribution in N-H and Si-H bonds are sensitive to process temperature, suggesting that thermally driven N incorporation reactions are important during growth. Inert gas dilution allows films to be formed at <100 °C, with bonded hydrogen configurations similar to films deposited at higher temperatures. Current versus voltage traces of as-deposited films show charge trapping, which can be reduced by extended low temperature anneals. These results show that chemical composition can be controlled in low temperature silicon nitride deposition. This processing approach may be useful for encapsulation or for barrier layer formation on low temperature organic electronic devices or flexible transparent plastic substrates.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Klein, TM and Anderson, TM and Chowdhury, AI and Parsons, GN}, year={1999}, pages={108–112} }
 @article{chowdhury_klein_anderson_parsons_1998, title={Silane consumption and conversion analysis in amorphous silicon and silicon nitride plasma deposition using in situ mass spectroscopy}, volume={16}, ISSN={["0734-2101"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000074150500084&KeyUID=WOS:000074150500084}, DOI={10.1116/1.581117}, abstractNote={In situ mass spectroscopy is used to sense plasma deposition of silicon and silicon nitride, to analyze gas phase reactant depletion, and the efficiency of silane conversion into the thin film. A double-differentially pumped quadrupole mass spectrometer was used to monitor the SiH4, Si2H6, and H2 effluent from 100% SiH4 and 2% SiH4/He silicon deposition, and SiH4/He/N2 silicon nitride deposition processes. No significant changes in gas phase nitrogen related species were observed during nitride deposition. However, the Si species show significant process dependence allowing reaction analysis. Disilane species were produced at low powers in the SiH4/He/N2 process, but no amino–silane species were observed. The silane consumption and silicon incorporation efficiency are shown to depend on gas dilution, residence time, and reactor geometry.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Chowdhury, AI and Klein, TM and Anderson, TM and Parsons, GN}, year={1998}, pages={1852–1856} }