Modeling effect of Negative Bias Temperature Instability on potential distribution and degradation of double-gate MOSFETs

In this work, the effect of negative bias temperature instability (NBTI) on the potential distribution and degradation of floating-body (FB) undoped double-gate (DG) MOSFETs is modeled. The approach is based on solving the one-dimensional (1-D) Poisson´s equation considering the NBTI effect in the inversion region. The study includes different stress voltages and device body thicknesses. The accuracy of the model is verified by the finite difference method (FDM). The results of the model are in very good agreement with those of the numerical method. These results show that in FB devices, the accumulation of the NBTI stress generated electrons in the device body reduces the body potential and oxide field and as a result decrease the generation of interface traps and degradation of device compared to the case that these electrons did not exist. In addition, the results show that because of larger volume density of generated electrons in devices with thinner bodies, the reduction of the oxide field is larger which lead to a decrease in generation of interface traps in them.