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 ZrO 2 and HfO 2 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 HfO 2 and ZrO 2 films, respectively. Zr(tmnd) 4 and Hf(tmnd) 4 lead to significantly higher growth rates of ZrO 2 and HfO 2 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.