Selective Atomic Layer Deposition of TiO2

A selective atomic layer deposition of TiO ₂ on Si and SiO ₂ in preference to SiCOH has been developed. This process utilizes Ti(O ⁱ Pr) ₄ and acetic acid (AcOH) as the co-reactants and deposits TiO ₂ on Si and SiO ₂ but not on SiCOH. It is found that 3 nm of TiO ₂ may be grown on Si and SiO ₂ before significant deposition on SiCOH occurs and the deposited films have RMS roughnesses of 2-3 Å. The selectivity is attributed to the inherent non-reactivity of -CH3 groups on SiCOH and the mechanism is shown to proceed via activation of the Si-H, Si-OH, and Ti-O ⁱ Pr surfaces by reaction with AcOH.