$Si(100)–SiO2$ interface properties following rapid thermal processing

An experimental examination of the properties of the $Si(100)–SiO2$ interface measured following rapid thermal processing (RTP) is presented. The interface properties have been examined using high frequency and quasi-static capacitance-voltage (CV) analysis of metal-oxide-silicon (MOS) capacitor structures immediately following either rapid thermal oxidation (RTO) or rapid thermal annealing (RTA). The experimental results reveal a characteristic peak in the CV response measured following dry RTO and RTA $(T>800 °C),$ as the Fermi level at the $Si(100)–SiO2$ interface approaches the conduction band edge. Analysis of the QSCV responses reveals a high interface state density across the energy gap following dry RTO and RTA processing, with a characteristic peak density in the range $5.5×1012$ to $1.7×1013 cm−2 eV−1$ located at approximately 0.85–0.88 eV above the valence band edge. When the background density of states for a hydrogen-passivated interface is subtracted, another peak of lower density $(3×1012$ to $7×1012 cm−2 eV−1)$ is observed at approximately 0.25–0.33 eV above the valence band edge. The experimental results point to a common interface state defect present after processes involving rapid cooling $(101–102 °C/s)$ from a temperature of 800 °C or above, in a hydrogen free ambient. This work demonstrates that the interface states measured following RTP $(T>800 °C)$ are the net contribution of the $Pb0/Pb1$ silicon dangling bond defects for the oxidized Si(100) orientation. An important conclusion arising from this work is that the primary effect of an RTA in nitrogen (600–1050 °C) is to cause hydrogen desorption from pre-existing $Pb0/Pb1$ silicon dangling bond defects. The implications of this work to the study of the $Si–SiO2$ interface, and the technological implications for silicon based MOS processes, are briefly discussed. The significance of these new results to thin oxide growth and optimization by RTO are also considered.