Low frequency noise modeling of SOI MOSFETs using Green´s function approach

In this paper, we present a new numerical model of the inversion charge power spectral density in FDSOI MOSFET devices with ultra thin body. Unlike previous classical models, we don´t use the equivalent concept which relates the fluctuation of the oxide charge to the flat-band voltage fluctuation. Localized noise sources in the oxide are implanted into the model and by using a Green´s function approach, the spectral cross-correlation of the electrical potential is evaluated at each node in the device mesh in order to obtain a highly accurate physical description. In this paper, we evaluate the validity of the classical model. In view of this, we have compared simulation results to those of the classical formulation and to experimental data. A good agreement with measurements is obtained with the proposed model. The results show that the noise behavior in FDSOI MOSFETs is strongly related to the front and buried oxides defects, even if the channel is located at the front interface. In other words the classical formulation of the flat-band voltage PSD overestimate the front oxide trap density and no more holds true in SOI MOSFETs LFN characterization.