Impact of trap creation at SiO2/Poly-Si interface on ultra-thin SiO2 reliability

Abstract

The relationship between TDDB characteristics of the devices having ultrathin SiO2 as gate dielectrics and the hydrogen-related trap creation have been re-investigated from the viewpoint of the oxidation process dependence. In order to study the influence of hydrogen on the reliability, deuterium isotope effect has been used. As a result, the Weibull distributions of time-to-breakdown (tBD) depends on the oxidation process condition even under the same oxidation temperature. Trap creation at gate oxide interface strongly correlates to the dielectric breakdown in ultra-thin gate oxides However, this oxidation process dependence could not be explained only by the amount of hydrogen release from SiO2/Si substrate interface From the experimental results of low-voltage SILC, it can be concluded that not only the released hydrogen from SiO2/Si substrate interface but also those from Poly-Si/SiO2 interface correlates to the breakdown mechanisms.