Abstract
Metal gate work function enhancement using nanoscale (1.0 nm)
Gd
2
O
3
interfacial layers has been evaluated as a function of silicon oxide content in the
Hf
x
Si
y
O
z
gate dielectric and process thermal budget. It is found that the effective work function tuning by the
Gd
2
O
3
capping layer varied by nearly 400 mV as the composition of the underlying dielectric changed from 0% to 100%
SiO
2
, and by nearly 300 mV as the maximum process temperature increased from ambient to
1000
°
C
. A qualitative model is proposed to explain these results, expanding the existing models for the lanthanide capping layer effect.