High Mobility High-Ge-Content SiGe PMOSFETs Using Al2O3/HfO2 Stacks With In-Situ O3 Treatment

We developed an Al
₂
O
₃
/HfO
₂
bi-layer gate dielectric with an in-situ O
₃
treatment for interface state density (D
_it
) and gate leakage current density (J
_g
) reductions on SiGe channels. We observed Ge-content dependent equivalent oxide thickness (EOT) scaling and EOT 0.44 nm was achieved with an MOS capacitor with a Si
_0.05
Ge
_0.95
substrate. The O
₃
treatment enabled application to non-planar device structures and we demonstrated five orders of magnitude lower off currents (I
_off
), a sub-threshold slope of 68 mV/decade, and a very high hole mobility of 457 cm
²
V
^-1
s
^-1
at an inversion carrier density (N
_inv
) of 1×10
¹³
cm
^-2
for asymmetrically strained SiGe PMOSFETs with Ge% of 65%-70%.