An improved analysis of low frequency trapping noise in a MOS device is proposed. This analysis takes into account the supplementary fluctuations of the mobility induced by those of the interface charge. It enables an adequate description of the gate voltage dependence of the input equivalent gate voltage noise to be obtained in various actual situations. The outputs given by the Hooge mobility fluctuation model are also presented and discussed with respect to those obtained by the carrier number fluctuation model. In particular, the impact of the channel length or channel width, and the model type on the input gate voltage and drain current noise characteristics is studied and compared to typical experimental data. Finally, a procedure for the diagnosis of the low frequency noise sources in a MOS transistor is proposed.

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A theoretical analysis of the impact of scaling down on the low frequency noise characteristics of silicon MOS transistors is presented. This analysis is based on the assumption that low frequency noise in large area MOS devices arises from the superposition of many RTS (random telegraph signal) fluctuators. An analytical formula for the input gate voltage noise in large area devices is derived from the RTS approach, reconciling the McWhorter and the RTS approaches. Moreover, we show that, for a realistic scaling law, the miniaturization of the devices will lead to an increase of the mean noise level linearly with the scaling factor and to a substantial (w three orders wide) sampleto-sample noise level dispersion, whereas for a classical scaling law, the mean noise is found to be independent of scaling. Finally, it is shown that the miniaturization will also result in a strong evolution of the noise spectra from l/f to Lorentzian like for devices with channel lengths from 1 to 0.1 Nm.Eine theoretische Analyse des Einflusses der Impulsuntersetzung auf die Niederfrequenzrauschcharakteristik von Si-MOS-Transistoren wird dargestellt. Die Analyse basiert auf der Annahme, daB niederfrequentes Rauschen in groBflachigen MOS-Bauelementen aus der Uberlagerung vieler RTS-Fluktuationen herruhrt. Aus der RTS-Naherung wird eine Formel fur das Eingangsgatespannungsrauschen in groBflachigen Bauelementen hergeleitet, die die Naherungen von McWorther und RTS in Einklang bringt. Weiterhin wird gezeigt, daI3 fur ein realistisches Untersetzungsgesetz die Miniaturisierung der Bauelemente das mittlere Rauschniveau linear mit dem Untersetzungsfaktor vergroBert und zu einer erheblichen Rauschniveaudispersion fuhrt, wahrend fur den klassischen Fall das Rauschniveau unabhangig vom Untersetzungsfaktor ist. SchlieBlich fiihrt eine Miniaturisierung zu einer starken Verschiebung des Rauschspektrums von einer l/f-zu einer Lorentz-Funktion hin fur Bauelemente mit Kanallangen zwischen 1 und 0,l pm.