1 research outputs found
Effects of Cl-Based Ligand Structures on Atomic Layer Deposited HfO<sub>2</sub>
Atomic layer deposition (ALD) of
HfO<sub>2</sub> is a key technology
for the application of high dielectric constant gate dielectrics ranging
from conventional Si devices to novel nanodevices. The effects of
the precursor on the growth characteristics and film properties of
ALD HfO<sub>2</sub> were investigated by using hafnium tetrachloride
(HfCl<sub>4</sub>) and bisÂ(ethylcyclopentadienyl)hafnium dichloride
(HfÂ(EtCp)<sub>2</sub>Cl<sub>2,</sub> HfÂ(C<sub>2</sub>H<sub>5</sub>C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Cl<sub>2</sub>) with O<sub>2</sub> plasma reactant. The growth characteristics were significantly
affected even by simply changing the precursor. Theoretical calculations
utilizing geometrical information on the precursor and density functional
theory revealed that the steric demands of the precursor ligands have
a dominant effect on the different growth characteristics rather than
the reaction probability of the precursor on the surface. The chemical
compositional analysis results showed that the Cl residue in the HfO<sub>2</sub> films was reduced by using HfÂ(EtCp)<sub>2</sub>Cl<sub>2</sub> due to the lower number of Cl atoms in each Hf precursor molecule
and the relieved bridge formation of Hf–Cl–Hf bridge
on the surface compared to HfCl<sub>4</sub>. The electrical property
measurement results showed significantly improved insulating properties
in HfO<sub>2</sub> using HfÂ(EtCp)<sub>2</sub>Cl<sub>2</sub> compared
to HfCl<sub>4</sub> due to the low concentration of Cl residue in
the film. These results provide broad insights to researchers who
are interested in the fabrication of high quality dielectric layers
to achieve better device performance and overcome physical limitations
in the nanoscale regime