Improved Ohmic Performance by the Metallic Bilayer Contact Stack of Oxygen-Incorporated La/Ultrathin TiSix on n-Si

This paper proposes a La/ultrathin TiSi
_x
metallic bilayer contact (MBC) on moderately doped n
⁺
-Si, which can simultaneously reduce contact resistivity (ρ
_c
) and at the same time improve the contact thermal endurance. In such an MBC, the top La defines the work function (WF), whereas the ultrathin (~1 nm) TiSi
_x
(WF-transparent) interlayer acts as a Si-diffusion barrier and improves the thermal endurance of the whole contact. Moreover, incorporation of oxygen (O) into MBC further improves the contact performance. On n
⁺
-Si with a donor concentration of 1 × 10
¹⁹
cm
^-3
, an O-incorporated MBC can achieve an 18.3× and 2.2× reduction in ρ
_c
as compared with Ti/n
⁺
-Si and La/n
⁺
-Si references, respectively.