Low-frequency noise assessment in advanced UTBOX SOI nMOSFETs with different gate dielectrics
Résumé
In this paper, UTBOX nMOSFETs with different gate dielectrics have been studied based on their lowfrequency noise (LFN) performance. Since LFN measurements have been successfully used as a characterization tool for determining the quality of the films, here, we have investigated the dielectric films used in state-of-the-art UTBOX devices in order to evaluate their performance and to identify the type of traps possibly introduced during the device processing. High-k gate dielectric devices have shown predominantly 1/f noise with a two-order of magnitude higher value than the conventional SiO2 ones which, consequently, results in higher density of traps in those devices. The carrier number fluctuations dominate the 1/f noise for both front and back interfaces. Due to the thin silicon film thickness there is a strong electrostatic coupling between front and back interfaces that interferes in the noise results as well as in transistor parameters. A contribution of the back interface noise source of about 14% on the measured noise in the front channel conduction was found, while the contribution of the front interface noise source is about 22% on the measured noise in the back channel conduction. The generation-recombination (GR) noise performed at different temperatures has enabled the identification of 6 types of traps and 2 unknown ones, being originated from the dry-etching or implantation damage.
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