IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electronics Wednesday Sessions
       Session EL-WeM

Paper EL-WeM9
Silicon-Oxide Formation on Gold

Wednesday, October 31, 2001, 11:00 am, Room 124

Session: Si Surface Dynamics and Reactions
Presenter: A.J. Slavin, Trent University, Canada
Authors: T. Vdovenkova, Trent University, Canada
A.J. Slavin, Trent University, Canada
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The Au-Si system has been well studied as a model system for metal-silicon interfaces. In contrast, the present work is one of the few studies of the growth of a silicon-oxide film on a gold substrate. The gold is the electrode, about 200-nm-thick, of a quartz-crystal microbalance (QCM) used for measuring the deposited mass. In early work on the deposition of Si onto a Au film about 10-nm thick, Si was visible in Auger spectroscopy (AES) from the start of evaporation. In contrast, in our study the evaporation of several monolayer-equivalents of Si under UHV conditions at room temperature resulted in the Si dissolving into the gold without the accumulation of any Si on the surface. Subsequent exposure to oxygen gas did not result in the segregation of Si to the surface. However, a layer of oxide from 0.5 to 1.8 nm thick was produced by a series of evaporations of the Si in the presence of O@sub2@ gas at 1 x 10@super -5@ torr with the sample held at 78@super o@C, probably aided by oxygen ions produced at the hot filament of the evaporator. The film growth has been studied by AES and EELS, using the QCM to monitor the amount of silicon oxide deposited. The average stoichiometry of the oxide was roughly SiO@sub 1.75@, based on an AES peak position of 78 eV compared to 92 for elemental bulk Si and 76 for SiO@sub 2@. One atomic layer of Si evaporated in vacuum onto the oxide film gave an AES peak at 90 eV, thought to be elemental Si; this showed that the Si oxide acted as a barrier to Si in-diffusion. This extra Si did not oxidize at 78@super o@C under O@sub 2@ gas at 1 x 10@super -5@ torr with the evaporator filament off. The intensity of the 90-eV peak decreased in comparison with the peak for Si in SiO@sub x@, under prolonged exposure to the electron beam. This research was supported by NSERC, Canada.