Experimental Study of the Impact of SO Phonon Scattering in High-κ Gate Dielectric MOSFETs

摘要

The phonon limited carrier mobility in MOSFETs is found to be accurately described by an exponential relationship over a wide range of temperature and electric field. It is shown that low temperature mobility is more sensitive to SO phonon scattering in comparison to high temperature mobility. Hence the impact of SO phonon scattering is not readily discerned using the conventional power law behaviour which shows significant deviation at low temperatures from experiment. It is established using the exponential model that the sensitivity factor, β, for TiN/HfO{sub}2 in these samples is about half that of poly-Si/HfO{sub}2 at T= 294K. Correspondingly the maximum SO limited mobility in poly-Si/HfO{sub}2 degrades by about 52% relative to TiN/HfO{sub}2 in the high field region at T =294 K whereas poly-Si/Hf silicate degrades by 22% in relation to SiO{sub}2. A combination of poly-Si/Hf silicate results in complete recovery from phonon scattering whereas TiN/HfO{sub}2 remains degraded by 35% at 150 K.