A Comprehensive Study of Thin Rapid Thermal Oxide Films

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Abstract
The kinetics of silicon oxidation by rapid thermal processing has been studied in the 1060-1240°C temperature range. Particular attention has been paid to homogenization and optimization of heating as well as to the initial conditions, that is, for example, sample preparation and initial thickness measurements. A great effort has also been made to achieve accurate measurements of temperature and oxide thicknesses using ellipsometry and the associated computations associated to it. The values of the experimental oxide film thickness have been compared to simulated ones, using Han and Helms' model [J. Electrochem. Soc. 134 (1987) 1297]. A good fit was found and it was concluded that rapid thermal oxidation (RTO) kinetics does not show any particular characteristics in the 2-20 nm range for the lightly doped silicon (ρ>2×10-2 Ω·cm). Electrical measurements on RTO capacitors have been performed. Typically, electrical field breakdown of 15 MV/cm and a charge injected at breakdown (Q bd) equal to 40 C cm-2 (J=1 A cm-2, A=1.6×10-4 cm2) were obtained for oxide thicknesses between 8 and 10 nm. These characteristics compare favorably with the best electrical properties reported in the literature using RTO. Hence, by enhancing temperature uniformity control and achieving process reproducibility, the RTO technique can become a promising candidate for submicron metal oxide semiconductor (MOS) technologies.