A structural transition region near the SiO2/Si interface has been considered to play an important role with respect to gate oxide reliability. We clarify the effects of the structural transition region on the time-dependent dielectric breakdown (TDDB) characteristics, particularly the activation energy of the oxide breakdown for ultrathin gate oxides formed by different oxidation processes, i.e., pyrogenic oxidation, rapid thermal O2 oxidation and N2O oxynitridation. Furthermore, we investigate the properties of the structural transition region, such as the density of SiO2 as measured by the grazing incidence X-ray-scattering reflectivity (GIXR) method, the Si-O-Si bond angle by Fourier-transform infrared attenuated total reflection (FTIR-ATR), the etching rate by chemical etching and X-ray photoelectron spectroscopy (XPS). Through these investigations, it is clarified that the oxide breakdown tends to occur at the Si-O-Si network with a lower bond angle (<15°) and that the strain in the structural transition region reduces the barrier to the oxide breakdown. A 1-nm-thick strained layer is found to have a strong effect on the oxide reliability and to limit oxide scaling in future ultra-large-scale integrated circuits (ULSIs).
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|出版ステータス||Published - 2000 12 1|
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