Epitaxial Growth of (Si)GeSn Source/Drain Layers for Advanced Ge Gate All Around Devices

Ge
_1-x
Sn
_x
and Si
_y
Ge
_1-x-y
Sn
_x
are being considered for novel device schemes as they have interesting electrical and optical material properties. We will show that the epitaxial material quality is higher if GeH
₄
, instead of Ge
₂
H
₆
, is used as Ge-source gas. Ge
_1-x
Sn
_X
is an interesting source/drain (S/D) material in Ge p-type FETs because the achievable electrically active boron doping concentration is a factor 60 higher than the boron solubility limit in Ge. We present a selective, conformally boron doped Ge
_1-x
Sn
_x
source/drain fabrication scheme implemented on 10 nm wide fins and on Ge based Gate-All-Around devices. N-doped Si
_y
Ge
_1-x-y
Sn
_x
is being considered as S/D material for nGe channels as Si:P suffers from degraded material quality when epitaxially grown on Ge.