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

New hafnium beta-diketonato-silylamide and siloxides namely Hf(thd)(2)[N(SiMe3)(2)](2) (1), Hf(thd)(2)(OSiMe3)(2) (2) and Hf(thd)(2)(OSit-BuMe2)(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(100) 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 similar to 80-100 kJ/mol, The as-deposited at 550-800 degrees C films were essentially amorphous; hafnia reflections appeared after 1 h annealing at 900 degrees 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 (similar to 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 (R-a similar to 0.7 nm, < 1% relative to thickness) HfSixOy films. Dielectric constant 11.3 and leakage current density 8 x 10(-4) A/cm(2) (at - 1 V) were measured for a 22 nm thick film. (c) 2006 Elsevier Ltd. All rights reserved.