The impact of carrier trapping at the substrate/buried oxide interface on the LF noise characteristics of Fully Depleted
MOSFETs has been calculated. The channel LF noise analysis based on carrier number fluctuation approach has been
extended to include charge variations at the substrate/buried oxide interface. The impact of fluctuations of substrate/BOX
interfacial charge on the channel drain current has thereby been studied as a function of gate bias. The results suggest
that substrate doping concentration, buried oxide thickness and dielectric material have non-negligible effect on the
contribution of the substrate interface noise to the total device noise. To our knowledge, the contribution of this noise to
the total noise of a FD-SOI device has never been studied.
In this paper, the LFN in partially and fully depleted SOI CMOS technologies is overviewed. Static performances of the devices are first presented. Then we address, for different types of architectures, the drain current fluctuations in both linear and saturation regimes. A particular attention is paid to the floating body effect that induces a kink-related excess noise, which superimposes a Lorentzian spectrum on the flicker noise. The behavior of this effect with the frequency and the physical mechanisms explaining this excess niose, are discussed. The control of this noise overshoot by using a body contact or by applying a back gate voltage is also demonstrated. On the other hand, the LFN in DTMOS, in ohmic and saturation regimes, is studied and the impact of the use of a current limiter is thoroughly analyzed. Finally, the influence of the oxide thickness thinning on the noise is shown.