Impact of Varying Strain Energy in Oxide on Random Telegraph Noise and Associated Time Constants in Silicon Nanowire pMOSFETs

Abstract

Multilevel random telegraph noise in gate-all-around silicon nanowire pMOSFET shows gate voltage overdrive-dependent interstate transitions, statistical count of which indicates the existence of oxide traps with different time constants. Following the detail extraction of the capture and emission time with gate bias, both have been found to deviate from the usual trend, as predicted by the conventional Shockley–Read–Hall statistics. Two traps in the gate–oxide have been found, in which the near interface is found to respond through the altered RTN activation energy barrier by spatially varying oxide residual strain energy, whereas the farther responds under the weak influence of the oxide strain energy. On the other hand, the emission time of near interface trap has been found to follow similar strain influenced activation barrier, but the magnitude of the emission time of the farther trap shows the hole emission through the p+ polysilicon gate–oxide interfacial trap, while favored by the electrostatic field in oxide. From RTN distributions and time lag plots, interstate transitions and state suppression in RTN are explained under the framework of two-trap postulate, in order to elucidate the unusual gate bias dependence of the measured trap time constants in silicon nanowire pMOSFETs.