Hafnium and zirconium tetramethylnonanedionates as new MOCVD precursors for oxide films

New bulky Zr and Hf β-diketonates (2,2,8,8-tetramethyl-4,6-nonanedionates, tmnd) were synthesized and characterized by elemental analyses, 1H NMR, FT-IR and mass spectrometry. A volatile copper compound Cu(tmnd)2, an intermediate product of ligand synthesis, was isolated and characterized as well. The M(tmnd)4 (M=Zr, Hf) compounds were tested as precursors for MOCVD of ZrO2 and HfO2 films. Preferentially (001)/(010)/(100) textured and in-plane oriented films of monoclinic oxides have been deposited by pulsed liquid injection MOCVD on R plane sapphire. Smooth films could be grown, especially on sapphire and at low temperature (500 °C). The films on Si(100) were polycrystalline and had rougher surface. XPS study showed 3-4 and 7-8 at.% of carbon in HfO2 and ZrO2 films, respectively. Zr(tmnd)4 and Hf(tmnd)4 lead to significantly higher growth rates of ZrO2 and HfO2 films at low temperature than conventional Zr(thd)4 and Hf(thd)4 precursors (thd=2,2,6,6-tetramethyl-3,5-heptanedionate) and are attractive precursors for oxide films.