Impact of Fin Doping and Gate Stack on FinFET (110) and (100) Electron and Hole Mobilities

Double-gate FinFET (110) (110) and (100) (100} electron mobility (μe) and hole mobility (μh) are experimentally investigated for the following: 1) a wide range of boron and phosphorus fin doping concentrations and 2) a wide variety of gate stacks combining HfO2, SiO2, or SiON insulators with TiN or poly-Si electrodes. It is found out that, irrespective of fin doping and gate stack, (110) (110) μeis competitive with the (100)(100) μe, while (110)(110) μhis ≥ 2× higher than (100) (100) μh. Inversion μeand μhare independent of doping as long as the effective field/doping combination enables the screening of the depletion charge. Mobility degradation with doping is significantly lower in accumulation mode (AM) than in inversion mode (IM) such that, for heavily B-doped fins, AM hole mobility exceeds the IM electron mobility even in (100) FinFETs. In undoped fins, ALD TiN gate stress is observed to improve μefor both orientations without degrading μh.