A study on film formation mechanisms and precursor/solvent compatibility in PP-MOCVD of Al2O3 films using aluminum tri-sec-butoxide with hexane and toluene

Pulsed pressure metal-organic chemical vapor deposition (PP-MOCVD) has been used to deposit aluminum oxide films using aluminum tri-sec-butoxide (ASB) as a precursor and hexane and toluene as solvents at 475 °C. Comparisons between solvent compatibility with ASB have been made. In addition to the solvents, different precursor/solvent solution concentrations (0.125 mol% and 0.5 mol%) and a shield have been used to investigate film formation mechanisms. This was done by studying the influence of these parameters on film properties (morphology and deposition rate). A droplet vaporization numerical model has been used to support explanations given for the dependence of properties on the process parameters. The results suggest that film formation might take place by four mechanisms including vapor phase deposition, Leidenfrost aerosol formation, homogeneous particle formation and liquid droplet impingement. The results also suggest that hexane has a better compatibility with ASB and is a better solvent than toluene.