Thermal Stability and Sn Segregation of Low-Resistance Ti/p+-Ge0.95Sn0.05 Contact

The thermal stability and contact property of Ti/p
⁺
-Ge
_0.95
Sn
_0.05
contact are investigated for the first time. Sn segregation is observed under the Ti/GeSn interface after the post-metal anneal (PMA). The specific contact resistivity Pc of Ti/p
⁺
-Ge
_0.95
Sn
_0.05
contact decreases significantly after PMA. Ultra-low Pc of 9.3 x 10
^-10
Ω-cm
²
is achieved after PMA at 450 °C for 30 s for Ti/p
⁺
-Ge
_0.95
Sn
_0.05
contact, which is about 4 times smaller than that of the as deposited Ti/p
⁺
-Ge
_0.95
Sn
_0.05
contact. Further increase in the PMA temperature to 500 °C leads to severe Ti grooving and contact-to-contact variations while the ultra-low Pc is maintained after PMA at 420 °C for 1 hour.