The titanium nitride (TiN) gate electrode with a tunable work function has successfully been deposited on the sidewalls of upstanding Si-fin channels of FinFETs by using a conventional reactive sputtering. It was found that the work function of the TiN (phi_TiN) slightly decreases with increasing nitrogen (N₂) gas flow ratio, R_N=N₂/(Ar+N₂) in the sputtering, from 17% to 100%. The experimental threshold voltage (V_th) dependence on the R_N shows that the more R_N offers the lower V_th for the TiN gate n-channel FinFETs. The composition analysis of the TiN films with different R_N showed that the more amount of nitrogen is introduced into the TiN films with increasing R_N, which suggests that the lowering of phi _TiN with increasing R_N should be related to the increase in nitrogen concentration in the TiN film. The desirable V_th shift from -0.22 to 0.22 V was experimentally confirmed by fabricating n⁺ poly-Si and TiN gate n-channel multi-FinFETs without a channel doping. The developed simple technique for the conformal TiN deposition on the sidewalls of Si-fin channels is very attractive to the TiN gate FinFET fabrication

Ultranarrow and ideal rectangular cross section silicon(Si)-Fin channel double-gate MOSFETs (FXMOSFETs) have successfully been fabricated for the first time using [110]-oriented silicon-on-insulator (SOI) wafers and orientation-dependent wet etching. The transconductance (g/sub m/) normalized by 2×(Fin height) is found to be as high as 700 μS/μm at V/sub d/=1 V in the fabricated 13-nm-thick and 82-nm-high Si- Fin channel double-gate MOSFET with a 105-nm gate length and a 2.2-nm gate oxide. The almost-ideal S-slope of 64 mV/decade is demonstrated in a 145-nm gate length device. These excellent results show that the Si-Fin channel with smooth [111]-oriented sidewalls is suitable to realize a high-performance FXMOSFET. The short-channel effects (SCEs) are effectively suppressed by reducing the Si-Fin thickness to 23 nm or less.

Variability of TiN FinFET performance is comprehensively studied. It is found that the variation of the in the FinFET occurs and the standard deviations of the of nMOS and pMOS FinFETs are almost the same. From the analytical results, it is found that the variation of the TiN FinFET is due to the work function variation (WFV) of TiN metal gate. The WFV is also responsible for the on-current variation.

In this letter, we propose a synthetic electric field (SE) effect to enhance the performance of tunnel field-effect transistors (TFETs). The novel SE-TFET architecture utilizes both horizontal and vertical electric fields induced by a gate electrode that is wrapped around an ultrathin epitaxial channel. The drain current of the SE-TFET is increased up to 100 times in comparison with those of conventional TFETs. The subthreshold slope of the SE-TFET also improved, and enhanced to 52 mV/decade by scaling the channel width and channel thickness.

Cointegration of titanium nitride (TiN)-gate high-performance tied-gate three-terminal FinFETs with symmetric gate-oxide thicknesses (t_ox1=t_ox2=1.7 nm) and variable threshold-voltage V_th independent-gate four-terminal (4T) FinFETs with asymmetric gate-oxide thicknesses (t_ox1=1.7 nm for the driving-gate-oxide, and t_ox2=3.4 or 7.0 nm for the control-gate-oxide) has been successfully developed using conventional reactive sputtering, two-step Si-fin and gate-oxide formation, and resist etch-back processes. A significantly improved subthreshold slope and an extremely low OFF-state current I_off are experimentally confirmed in the asymmetric gate-oxide thickness 4T FinFETs by increasing the control-gate-oxide thickness to twice or more the driving-gate-oxide thickness. The developed techniques are attractive for high-performance and low-power FinFET very large-scale integration circuits

The FT-FinFETs with independent double gates and an ideal rectangular cross-section Si-Fin channel have successfully been fabricated by using newly developed orientation-dependent wet etching. The flexible V/sub th/ controllability by using one of the double gates as a control gate and by the synchronized driving mode operation is experimentally confirmed. The developed processes are attractive for the fabrication of the advanced separate-gates FinFET for a flexible function VLSI circuit.