Gate-First Integration of Tunable Work Function Metal Gates of Different Thicknesses Into High-$k$/Metal Gates CMOS FinFETs for Multi- $V_{\rm Th}$ Engineering

Gate-first integration of tunable work function metal gates of different thicknesses (3-20 nm) into high-k/metal gates CMOS FinFETs was demonstrated to achieve multiple threshold voltages (V
_Th
) for 32-nm technology and beyond logic, memory, input/output, and system-on-a-chip applications. The fabricated devices showed excellent short-channel effect immunity (drain-induced barrier lowering ~40 mV/V), nearly symmetric V
_Th
, low T
_inv
(~1.4 nm), and high I
_on
(~780 ¿A/¿m) for N/PMOS without any intentional strain enhancement.