Investigation on Contacts Thermal Stability for 3D Sequential Integration

Contacts stability versus thermal budget is a major concern in 3D sequential integration. We experimentally investigate the thermal stability of n-type contacts on Si and p-type contacts on SiGe in terms of specific contact resistivity (ρ
c
). An improved ρ
cn
performance featuring lower magnitude and better thermal stability has been demonstrated for Ti silicide contacts on n
⁺
-Si with Ge pre-amorphization implantation (PAI). For p-type contacts, it is found that Ni has lost its high work function advantage on p
⁺⁺
-SiGe and Ti germanosilicide contacts show ρ
cp
outperformance. CMOS contact scheme based on single Ti instead of dual Ti and Ni has hence been evidenced to be more suitable for 3D sequential integration.