Mobility issues in ultra-thin SOI MOSFETs: thickness variations, GIFBE and coupling effects

The impact of film thickness variation and ultrathin gate oxide on the carrier mobility is investigated in 10-15 nm thick SOI MOSFETs. Once the parasitic resistance effect was eliminated, the mobility is independent of SOI thickness. A difference between front and back channel mobility is observed and discussed. In SOI MOSFETs with ultra-thin gate oxide, gate-induced floating body effects occur, leading to mobility overestimation, in particular at low temperature. In ultra-thin SOI films, super-coupling between the front and back channels can also be responsible for a mobility misevaluation.