Suppressing Vt and Gm variability of FinFETs using amorphous metal gates for 14 nm and beyond

Amorphous TaSiN metal gates (MGs) are successfully introduced in FinFETs to suppress work function variation (WFV) of the MG, which is a dominant contributor to threshold voltage (V
t
) variability of the undoped channel MG FinFETs. Comparing with a poly-crystalline TiN gate, the TaSiN gate reduces V
t
variation drastically and records the smallest A
Vt
value of 1.34 mVμm reported so far for MG FinFETs. Interface traps also become a dominant A
Vt
origin in the case of well-suppressed WFV using the amorphous M G. The WFV suppression is also effective to reduce trans-conductance (G
m
) variability which will be a dominant source of on-current (I
on
) variability in 14 nm technology and beyond.