Aluminum deposition by ultraviolet laser photofragmentation of trimethylaluminum on Al: Identification of photoproducts and desorption dynamics Available to Purchase

Important new mechanistic details regarding aluminum deposition by excimer laser photodecomposition of trimethylaluminum adsorbed on aluminum covered SiO₂/Si surfaces have been obtained using a time‐of‐flight quadrupole mass spectrometer. CH₃ radicals and Al–(CH₃)_n(n=1,2,3) species desorb efficiently at 193 nm leaving the surface with up to 0.22 eV of translational energy. No evidence is found for desorption of Al from the surface indicating that Al is more tightly bound than methyl‐aluminum fragments. A threshold behavior in the laser intensity dependence of the time‐of‐flight transient intensity for Al(CH₃)₂ and AlCH₃ fragments suggests a dissociation mechanism involving stepwise removal of methyl fragments. Desorbed fragment translational energy depends upon surface coverage indicating a distribution of surface binding sites. Finally, no evidence of ethane or methane desorption from the sample surface is found implying that radical recombination and hydrogen abstraction are primarily secondary gas phase reactions which are not surface initiated.