MOCVD growth of HfSixOy films from hafnium β-diketonato silylamides and siloxides

New hafnium β-diketonato-silylamide and siloxides namely Hf(thd)2[N(SiMe3)2]2 (1), Hf(thd)2(OSiMe3)2 (2) and Hf(thd)2(OSitBuMe2)2 (3) (thd=2,2,6,6-tetramethyl-3,5-heptanedionate) were investigated as single-source precursors for low-pressure pulsed liquid injection MOCVD of HfSixOy thin films on Si(1 0 0) and R-plane sapphire. Films were characterized by XRD, XPS and AFM. The growth rate increased in order 1>2>3 in agreement with the decreasing precursor thermal stability. The activation energy was ∼80–100 kJ/mol. The as-deposited at 550–800 °C films were essentially amorphous; hafnia reflections appeared after 1 h annealing at 900 °C probably due to phase separation into amorphous Si-rich silicate and crystallized HfO2. The surface of the films showed similar amounts of Hf and Si (∼1:1) and was overstoichiometric in oxygen (ratio O/(Hf+Si) >2). The bulk of the films was Hf-rich (70–85% of Hf/ Hf+Si) and slightly oxygen-deficient. The new complexes are attractive single-source precursors for the deposition of pure and very smooth (Ra∼0.7 nm, <1% relative to thickness) HfSixOy films. Dielectric constant 11.3 and leakage current density 8×10−4 A/cm2 (at −1 V) were measured for a 22 nm thick film.