CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

6.1.3 DLI-CVD of barium titanate films
Epitaxial growth of BaTiO3 films on MgO (100) substrate has been obtained by DLI-
CVD technique. Good single crystal quality has been illustrated by the results of ω and ϕ-scan.
Thin film growth rate of ~0.5 μm hr is achieved under our experimental conditions. Surface and
cross sectional morphology characterization shows large surface roughness and interface voids,
which can be contributed to the island mode thin film growth. Incorporation of small amount of
F elements in the thin film has been verified by XPS analysis. Instead of forming crystalline
BaF2 phase, the F elements bonds to the Ba ions in amorphous state.
6.2 Future work
PEALD of HfN by using TDMAH and hydrogen plasma has been limited by thin film
contamination from incorporation of C. In spite of the increased conductivity of thin films
deposited at high plasma powers, the C concentration is not affected much by the plasma power.
This is directly related to the chemical reaction mechanisms between TDMAH and hydrogen
plasma. To improve the as deposited thin film quality, substrates with smaller lattice mismatch
can be selected, such as MgO(100) (7%). To improve the thin film purity, more appropriate
reducing agent than hydrogen plasma should be selected. Dimethyl hydrazine (H2NN(CH3)2),
which has been successfully used in thermal CVD of HfN thin films, might be a good candidate
for this PEALD experiment to replace hydrogen.[70] Potential advantages include: low plasma
power is needed to break the weak N=N bond and the -NH2 group is more readily to react with
the central Hf atom and work as an external N source.[174]
Single crystalline spinel ferrite films, including nickel ferrite and lithium ferrite, have
been successfully deposited on certain small lattice match substrates by DLI-CVD method. For
nickel ferrite deposition, more work can be focused on the deposition on piezoelectric substrates,
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