Selective Pulsed Chemical Vapor Deposition of Water-Free TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 Nanolaminates on Si and SiO 2 in Preference to SiCOH.

Highly selective and smooth TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates were deposited by water-free pulsed chemical vapor deposition (CVD) at 300 °C using titanium isopropoxide (Ti(O i Pr) 4 ) and hafnium tertbutoxide (Hf(O t Bu) 4 ) with trimethylaluminum (TMA). TMA was found to be the key factor for enhancing nucleation selectivity on SiO 2 or Si versus SiCOH (hydrophobic, nonporous low k dielectric). With precise dosing of TMA, selective nucleation of TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates was achieved and smoother films were formed with higher selectivity compared to single precursor TiO 2 and HfO 2 CVD. The selectivity of TiO 2 /Al 2 O 3 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 HfO 2 /Al 2 O 3 deposition increased from 14 to 73, while the RMS roughness of HfO 2 /Al 2 O 3 on Si was maintained at a similar value of 0.78 nm. Deposition of water-free pulsed CVD TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 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 TiO 2 /Al 2 O 3 and HfO 2 /Al 2 O 3 nanolaminates can be formed on a nanoscale pattern.