Simulation of Random Telegraph Noise in Nanometer nMOSFET Induced by Interface and Oxide Trapped Charge

Abstract

In this work, the influence of a single positive elementary charge trapped either in the oxide or at the oxide-semiconductor interface on Random Telegraph Noise (RTN) has been investigated and the relative RTN amplitude ΔI D ∕ I D in nanometer MOSFET was simulated. Since our investigations were focused on the RTN amplitude, we considered only the steady-state and did not investigate the dynamics of charging/discharging the trap.For considering the impact of a single charge trapped in the oxide or at the interface, we assumed that this single positive charge was homogeneously distributed across a certain gate oxide volume or across a certain interface area. By varying the length of the charged region, containing a homogeneously distributed single charge, from 54 nm down to 0.8 nm, it is found that the RTN amplitude in-creases for decreasing length and reaches saturation for lengths below 20 nm.For identical extensions and positions in the gate length direction, a trapped interface charge generates a RTN amplitude up to two times larger compared to a charge trapped in the oxide. For both oxide and interface charges the maximal RTN amplitude is observed for a trap located right above the center of the channel. Results show that the main contribution to the RTN amplitude comes from the variation of the carrier density in the channel due to the trapped charge.