Direct comparison of Si/High-K and Si/SiO2 channels in advanced FD SOI MOSFETs

Detailed measurements of front and back channel characteristics in advanced SOI MOSFETs (ultrathin film, metal gate, selective epitaxy of source/drain) are used to reveal the transport properties at the corresponding Si/high-K (HfO
₂
/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 to Si/SiO
₂
, the mobility is lower at the Si/high-K interface and increases less rapidly at low temperature, reflecting additional scattering mechanisms governed by high-K and neutral defects.