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 SiO2 gate insulating layer from VA characteristics measured in wide temperature range (gate electrode area 1.5 μm2, 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 I0 = (1–3)×10−16 A and ideality factor near to 1. Saturation current value corresponds to Schottky barrier high about 1.2 eV. We suppose that in SiO2 gate insulating layer and on the interface Si‐SiO2 there are oxygen vacancies and interstitials. High density of overlapping energy localized states creates in SiO2 impurity conduction band about 1.2 eV above the Si conduction band. Between channel and interface Si‐SiO2 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 lnm from channel. These quantum transitions are sources of RTS noise. Electron from channel trap can tunnel to interface Si/SiO2 localized state or it can enter through SiO2 impurity conductivity band to gate electrode by thermionic emission.