Synthesis and characterization of Hf–Al heterometallic aminoalkoxides as single-source MOCVD precursors for hafnium aluminate films

Alcohol exchange reactions applied to HfAl2(OPri)10 (1) afforded heterometallic Hf–Al aminoalkoxides namely HfAl2(OPri)8(dmae)2 (dmae = N,N-dimethylaminoethoxide) (2) and HfAl2(OPri)8(dmap)2 (dmap = dimethylaminopropoxide) (3). They were characterized by elemental analysis, FT-IR, 1H NMR, mass spectrometry and TGA. The molecular structure of 2, as established by single-crystal X-ray diffraction, HfAl2(μ-OPri)2(μ,η2-OC2H4NMe2)2(OPri)6, is based on an open-shell trinuclear unit with a central 6-coordinate Hf atom and 5-coordinate Al centres. Compound 2 was tested as a single-source precursor for the deposition of hafnium aluminate films by liquid-injection MOCVD. The films growth rate, composition and morphology were studied in relation with the deposition temperature. The as-deposited at 500–800 °C films (both on sapphire and silicon) were amorphous; partial crystallization occurred after 1 h annealing at 900 °C. The bulk of the films was Al-rich (Al/Hf = 1.2–1.6) and contained small amounts of carbon (2–4%) and nitrogen (4–5%).

The first Hf–Al aminoalkoxide HfAl2(μ-OPri)2(μ,η2-OC2H4NMe2)2(OPri)6 has been structurally characterized. It is an attractive single-source precursor for liquid-injection MOCVD of (HfO2)x(Al2O3)1 − x films. These were characterized by XRD, AFM and XPS.Figure optionsDownload as PowerPoint slide