Abstract
Metal gate work function enhancement using thin
Al
N
x
interfacial layers has been evaluated. It was found that band edge effective work functions
(
∼
5.10
eV
)
can be achieved on hafnium-based high dielectric constant (high-
k
) materials using the
Al
N
x
interfacial layer and TiSiN electrodes. It was also found that the effective work function enhancement by the
Al
N
x
interfacial layer increased when the concentration of
Si
O
2
in the gate dielectric was increased. Thus, the enhancement was minimal for
Hf
O
2
and maximum for
Si
O
2
. A model is proposed to explain these results and a bonding analysis is presented to support the proposed model.