In Situ Spectroscopic Ellipsometry Studies of The Interaction Process of Ethene With Si Surfaces During Sic Formation
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T. W5hner*,**, Th. Stauden*, V. Cimalla*, G. Eichhorn*, J.A. Schaefer**, J. Pezoldt* *TU Ilmenau, Institut fir Festkirperelektronik, PF 100565, D-98684 Ilmenau, Germany, **TU Ilmenau, Institut fiir Physik, PF 100565, D-98684 Ilmenau, Germany [email protected]
ABSTRACT The interaction of ethene with silicon (111) surfaces at different process temperatures (580'C, 680'C, 780 0 C) was monitored in situ by spectroscopic ellipsometry. It is shown that spectroscopic ellipsometry is a reliable method to monitor the carbonization process of silicon surfaces. Different SiC formation stages (incubation time, (V3xV3)R300 reconstruction, 2D growth and 3D growth) were observed using complimentary analyzing techniques. The change of the ellipsometric signal as a function of process time is related to these stages and was interpreted using an optical model which consists of four layers (surface roughness, SiC layer, interface layer, Si substrate).
INTRODUCTION The interaction of hydrocarbons with silicon surfaces is important from the point of view of conversion of silicon into silicon carbide 'buffer' layers, as well as for contamination control. The carbonization process of silicon surfaces can be performed under ultra high vacuum (UHV) conditions with molecular beam epitaxy (MBE) equipment, or at normal or low pressures in a conventional chemical vapour deposition reactor or a rapid thermal processing chamber. We need
to develop an in situ monitoring method of this process which can be used under these different conditions. One way is the application of a technique based on the interaction of light with solid surfaces, e.g. spectroscopic ellipsometry. Ellipsometry is nondestructive and very fast, and so it is well applied for in situ analysis of growing films [1-3]. However, it has not been used as an in situ method to monitor the carbonization process until now. We want to show that ellipsometry is suited for this application. The in situ data were described by an optical model which consists of three layers and the substrate.
EXPERIMENT The interaction process of ethene with silicon surfaces was investigated under ultra high vacuum conditions (UHV, base pressure of
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