TaSi2gate for VLSI CMOS circuits

It is shown, that lateral shrinkage of 2-µm CMOS devices and reduction of the gate oxide thickness to about 20 nm is significantly facilitated by replacing the n
⁺
-poly-Si or polycide gates by TaSi
2
. Due to its higher work function, TaSi
2
allows the simultaneous reduction of the channel doping in the n-channel and the charge compensation in the p-channel without changing the threshold voltages. Thus compared with n
⁺
-poly-Si gate n-channel transistors substrate sensitivity and substrate current are reduced, and low-level breakdown strength is raised. In p-channel transistors, the subthreshold current behavior and U
T
(L)-dependence are improved. Consequently, the channel length of both n- and p-channel transistors can be reduced by about 0.5 µm without significant degradation. The MOS characteristics N
ss
, flatband and threshold voltage stability, and dielectric strength appear similar for TaSi
2
and n
+
-poly Si gate transistors.