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The hydrophilicity of the silicon wafer surface caused by hydroxylgroups and physisorbed water plays an essential role in silicon wafer direct bonding. Different wafer pretreatments from the literature are tested applying the contact angle method for the estimation of the hydrophilicity. Special attention is paid to the RCA clean and ageing processes of the surface. The doping and the orientation of the silicon wafers influence the desorption of water during ageing. The best hydrophilization method forming fully hydrated surfaces with very good long time stability is the plasma activation. Die Hydrophilitat der Siliziumoberflache, hervorgerufen durch Hydroxylgruppen und physiosorbiertes Wasser hat eine groDe Bedeutung fur das groDflachige Direktbonden von Siliziumscheiben. Verschiedene Scheibenvorbehandlungen aus der Literatur werden mit Hilfe der Randwinkelmethode getestet. Besondere Aufmerksamkeit wird der KERN-Reinigung und Alterungsprozessen der Obertlache gewidmet. Die Dotierung und die Orientierung der Scheiben beeinflussen die Desorption von Wasser bei der Alterung. Die beste Methode zur Scheibenhydrophilisierung mit sehr guter Langzeitstabilitat ist die Plasmaaktivierung.

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The effect of the carbon content on the optical transitions of Si1−yCy layers grown pseudomorphically on Si(001) substrates was investigated by spectroscopic ellipsometry and electroreflectance spectroscopy for 0≤y≤0.012 in the energy range between 3 and 5 eV. The ellipsometry data show a decrease of the slope of the dielectric function near the critical points and a tendency of a critical point shift with increasing carbon content. This shift was analyzed by measuring and fitting electroreflectance spectra at 80 K, resulting in a weak and linear dependence on the carbon content at all transitions. The E1 critical point energy increases with an increasing carbon content while the E2 energy decreases, both at a rate of about 30 meV/%[C]. The E′0 transition decreases at a smaller rate of about 20 meV/%[C]. The results are discussed in the light of previous discussions and a simple estimate based on silicon deformation potentials.

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