Achieving Conduction Band-Edge Schottky Barrier Height for Arsenic-Segregated Nickel Aluminide Disilicide and Implementation in FinFETs With Ultra-Narrow Fin Widths

In this letter, we report the impact of incorporating aluminum (Al) in nickel aluminide disilcide (NiSi
<sub>2

-x</sub>
AI
_x
) on the Schottky-barrier for electrons (Phi
_B

ⁿ
) in NiSi
_2-x
Al
_x
/Si contacts for parasitic series resistance reduction. A wide range of Al concentration was investigated, and an optimum value was obtained. Based on the optimum Al concentration, arsenic- segregated NiSi
_2-x
Al
_x
(As-segregated NiSi
_2-x
Al
_x
) contacts were shown to achieve conduction band-edge Schottky-barrier heights with Phi
_B

ⁿ
= 0.133 eV. This novel As-segregated NiSi
_2-x
Al
_x
contact was integrated in FinFETs with a gate length of 80 nm and a fin width (W
_Fin
) of 11 nm, demonstrating improvement in current drivability of 30% over FinFETs with As-segregated NiSi contacts. We show that these ultranarrow fins (W
_Fin
= 11 nm) can be fully silicided reliably with NiSi
_2-x
Al
_x
, demonstrating scalability and the smallest fully silicided Si fins reported to date. For these ultra-narrow Si fins, we have successfully alleviated the concerns of parasitic series resistance without the use of selective epitaxial raised source and drain technology.