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

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