Selective Pulsed Chemical Vapor Deposition of Water-Free TiO₂/Al₂O₃ and HfO₂/Al₂O₃ Nanolaminates on Si and SiO₂ in Preference to SiCOH

Highly selective and smooth TiO2/Al2O3 and HfO2/Al2O3 nanolaminates were deposited by water-free pulsed chemical vapor deposition (CVD) at 300 °C using titanium isopropoxide (Ti(OiPr)4) and hafnium tertbutoxide (Hf(OtBu)4) with trimethylaluminum (TMA). TMA was found to be the key factor for enhancing nucleation selectivity on SiO2 or Si versus SiCOH (hydrophobic, nonporous low k dielectric). With precise dosing of TMA, selective nucleation of TiO2/Al2O3 and HfO2/Al2O3 nanolaminates was achieved and smoother films were formed with higher selectivity compared to single precursor TiO2 and HfO2 CVD. The selectivity of TiO2/Al2O3 nanolaminate deposition increased from 34 to 44 (deposition on Si vs SiCOH), while RMS roughness of the film of Si decreased from 2.8 to 0.38 nm. The selectivity of HfO2/Al2O3 deposition increased from 14 to 73, while the RMS roughness of HfO2/Al2O3 on Si was maintained at a similar value of 0.78 nm. Deposition of water-free pulsed CVD TiO2/Al2O3 and HfO2/Al2O3 nanolaminates was conducted on a Cu/SiCOH patterned sample to study their nanoselectivity. Transmission electron microscopy images of the Cu/SiCOH patterned sample demonstrated that highly selective and smooth TiO2/Al2O3 and HfO2/Al2O3 nanolaminates can be formed on a nanoscale pattern.