Improved Current Drivability for Sub-20-nm N-FinFETs by Ge Pre-Amorphization in Contact With Reverse Retrograde Profile

Prior to contact silicide formation, multiple Ge pre-amorphization implantation (PAI) with reverse retrograde Ge profile was investigated for sub-20-nm FinFETs. Compared with conventional single PAI, N-FinFETs from the new PAI scheme exhibit enhanced drive current by 12%, which can be attributed to decreased total series resistance (RTotal) by 15% and enhanced peak electron mobility by 8%. The former arises from reduced Schottky barrier height and better crystallinity of C49/C54 TiSi
₂
, while the latter is resulted from higher tensile strain in the channel induced by TiSi
₂
with more Ge incorporation. Furthermore, ring oscillator for the new PAI scheme shows better circuit performance as compared with conventional scheme in terms of 6% increase in output frequency. The newly developed PAI process is fully compatible with the incumbent ULSI technology and can be extended to sub-10-nm FinFETs.