Germanium N and P Multifin Field-Effect Transistors With High-Performance Germanium (Ge) ${\rm p}^{+}/{\rm n}$ and ${\rm n}^{+}/{\rm p}$ Heterojunctions Formed on Si Substrate

We demonstrate the characteristics of p
⁺
-Ge/n-Si and n
⁺
-Ge/p-Si heterojunction diodes formed by heteroepitaxial Ge grown on Si leading to high performance and very low leakage current. The ON/OFF current ratio of the p
⁺
-Ge/n-Si and n
⁺
-Ge/p-Si heterojunction was > 10
⁷
and > 10
⁶
, respectively. The OFF current density was extremely low at <; 10 μA/cm
²
for the p
⁺
-Ge/n-Si formed with different implantation energies of 10-40 KeV and ~ 20 μA/cm
²
for the n
⁺
-Ge/p-Si with different implantation energies of 20-50 KeV at a reverse bias of |
V
_R
| = ±1 V, respectively. Both p and n-Ge channel multifin field-effect transistors (FinFETs) were formed by a mesa structure using these p
⁺
-Ge/n-Si and n
⁺
-Ge/p-Si heterojunctions. A high-κ/metal gate stack was employed. The body-tied Ge multifin FinFET with a fin width (
W
_Fin
) of ~ 40 nm, and the channel length (L
_Channel
) was 150 nm for p-FinFET and of 110 nm for n-FinFET, exhibiting a driving current of 174 μA/μm at
V
_G
=-2 V and 102 μA/μm at
V
_G
=2 V , respectively. This is the first experimental demonstration of a body-tied high mobility Ge channel multifin FinFET using a top-down approach.