Hf(OSitBuMe2)2(acac)2 is has been synthesized and characterized ; it exhibits good properties in terms of hydrolysis stability and volatility.
Hf(OSitBuMe2)2(acac)2 was applied as single-source precursor for the deposition of hafnium silicate HfSiO layers on Si and Ge substrates by MOCVD for gate dielectric applications in metal–oxide–semiconductor devices. Precursor decomposition was affected by surface conditions: films deposited on Si wafers revealed high C contamination (up to 20 at %) and low Si content (up to 20 at %) ; in contrast, for HfSiO layers grown on Ge wafers, no C contamination has been detected, and Si incorporation was delayed – was startingonly after ca. 15 nm HfO2 dielectric growth. Crystallization of deposited films, Si and Ge redistribution in the dielectric, and interfacial layer growth has been observed after post-deposition rapid thermal annealing in an O2 atmosphere. Oxygen annealing was also found to significantly reduce EOT compared to as-deposited films (related to crystallization effects). Interfacial layer growth limited scaling of EOT. Leakage currents were mainly caused by trap-related conduction mechanisms ; energy levels of involved traps decreased with increasing crystallization and/or Hf content, and values of 0.5 eV and 1 eV related to Hf and Si bonds, respectively, were obtained.[[i]]
[i]M. Lemberger, F. Schön, T. Dirnecker, M. P. M. Jank, L. Frey, H. Ryssel, A. Paskaleva, S. Zürcher, A. J. Bauer, Chemical Vapor Deposition, 2007, Special Issue: EUROCVD-15, Vol 13, Iss 2-3, p 105–111, “MOCVD of Hafnium Silicate Films Obtained from a Single-Source Precusor on Silicon and Germanium for Gate-Dielectric Applications »
Heteroleptic hafnium alkoxide-diketonate Hf(OiPr)2(thd)2 precursor in combination with Si(OtBu)2(OAc)2 has been used for the growth of HfSiO films. The precursor was chosen because of its improved stability in the gas phase relative to alkoxides with similar low deposition temperatures. [538] HfO2 growth from this precursor at 590°C revealed mass-transport controlled behavior up to 10 mmol/min.