Epitaxial Germanium on SOI Substrate and Its Application of Fabricating High ION/ IOFF Ratio Ge FinFETs

Integrating germanium (Ge) thin film on silicon-on-insulator (SOI) substrate and fabricating Ge fin field-effect transistors (FinFETs) are demonstrated in this paper. Directly grown Ge film on a high-resistivity thin SOI substrate provides a good platform for fabricating advanced Ge devices. The SOI structure could effectively suppress junction leakage; therefore, highION/IOFFratio (~5×105, atVD=0.1 V) of the drain current is achieved. Tri-gate structure provides better short-channel control abilities for the Ge FinFETs, and the drain-induced barrier lowering and threshold voltage (VTH) shift can be maintained at the level of ~110 mV/V and ~ 0.1 V, respectively, for Ge n-channel FinFET withLchannel=120 nm andWFin=40 nm. Multifin Ge FinFET withLchannel=170 nm andWFin=50 nm is also illustrated. BothN- andP-FinFETs possess highION/IOFFratio over 104. Besides, the subthreshold swing could be reduced around 25% after forming gas annealing.