RTS and 1/f Noise in Submicron MOSFETs

摘要

The capture and emission time constants dependence on drain current for constant gate voltage and variable drain voltage show that probability for charge carrier capture decreases with increasing lateral electric field while emission process is independent on lateral field intensity. We have performed analyses of SiO_(2) gate insulating layer from VA characteristics measured in wide temperature range (gate electrode area 1.5 (mu)m~(2), insulating layer thickness 6 nm. Leakage current in reverse mode of n-MOS sample (for gate electrode negative) is for applied voltage lower than 1 V exponential function of applied voltage with saturation current I_(0) velence (1-3)X10~(-16) A and ideality factor near to 1. Saturation current value corresponds to Schottky barrier high about 1.2 eV. We suppose that in SiO_(2) gate insulating layer and on the interface Si-SiO_(2) there are oxygen vacancies and interstitials. High density of overlapping energy localized states creates in SiO_(2) impurity conduction band about 1.2 eV above the Si conduction band. Between channel and interface Si-SiO_(2) localized states exists g-r stochastic exchange of electrons, which is a source of 1/f noise. Reducing the density of interface states by plasma oxidation leads to 1/f noise spectral density lowering. There exists electron exchange by tunnelling between interface Si-SiO2 localized states and traps localized in gate insulating layer about 1nm from channel. These quantum transitions are sources of RTS noise. Electron from channel trap can tunnel to interface Si/SiO_(2) localized state or it can enter through SiO_(2) impurity conductivity band to gate electrode by thermionic emission.