In Situ Comparison of Si/High- $\kappa$ and $\hbox{Si}/ \hbox{SiO}_{2}$ Channel Properties in SOI MOSFETs

Detailed measurements of front- and back-channel characteristics in advanced SOI MOSFETs (ultrathin Si film, high-kappa, metal gate, and selective epitaxy of source/drain) are used to reveal and compare the transport properties at the corresponding Si/high- kappa (HfO
₂
or HfSiON) and Si/SiO
₂
interfaces. Low-temperature operation magnifies the difference between these two interfaces in terms of carrier mobility, threshold voltage, and subthreshold swing. As compared with Si/SiO
₂
, the low-field mobility is lower at the Si/high-kappa interface and increases less rapidly at low temperature, reflecting additional scattering mechanisms governed by high-kappa and neutral defects.