Properties of ultrathin SiO2 films grown on hydrogenated silicon

Igor Lisovskyy 1Vladimir G. Litovchenko 1D A. Mazunov 1A Szekeres 2S Alexandrova 2

1. Institute of Semiconductor Physics NAS Ukraine, Kyiv, Ukraine
2. Institute of Solid State Physics, Sofia, Bulgaria

Abstract

The optical and electrical properties of ultrathin (8-12 nm) SiO2 layers thermally grown at 850 oC on rf-hydrogen plasma-cleaned Si studied and are compared with those of oxides grown on standard RCA-cleaned Si. The structural characterization was performed using spectral ellipsometry and IR techniques. IR data was used for computer simulation of oxide structure. Characterization of electrically active defects has been performed by frequency dependent C-V technique. From the analysis of the pseudo-dielectric function of Si the oxidation-induced stress was evaluated. Its level was in the order of 108 N/m2 and was substantially smaller in plasma treated samples. An analysis of the IR spectra has shown that the structure of SiO2 grown on hydrogenated silicon possesses a contribution of 4- and 6-fold SiO4 tetrahedra rings. The structure of the standard oxides contains an additional contribution of SiO2Si2 molecular complexes. Their presence leads to increase of the distances between neighbouring Si atoms and to increase of stresses in SiO2 lattice. Electrical measurements of such structures have also revealed larger densities of interface defects (fixed oxide charge and interface traps). This is in correlation with content of SiO2Si2 clusters, which are known to contribute to the fixed oxide charge.

 

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Presentation: oral at E-MRS Fall Meeting 2003, Symposium A, by Igor Lisovskyy
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-20 13:42
Revised:   2009-06-08 12:55