TY - JOUR
T1 - Mechanisms of Al film growth by ultraviolet laser photolysis of trimethylaluminum
AU - Motooka, T.
AU - Gorbatkin, S.
AU - Lubben, D.
AU - Eres, Djula
AU - Greene, J. E.
PY - 1986/11
Y1 - 1986/11
N2 - Mechanisms for the UV photolytic deposition of Al by KrF irradiation of trimethylaluminum (TMA) in ultrahigh vacuum have been investigated. Based upon optical emission supectra combined with molecular orbital calculations, a model for the UV photolysis of dimerized TMA, A12(CH3)6, was developed in which Al and CH3were produced through cascade one-photon absorption processes in A12(CH3)6and A1(CH3)n(n 1, 2, 3). In addition, time-resolved fluorescence measurements showed that CH was also generated in the gas phase by a photolytic side reaction involving photofragments of TMA. Film growth kinetics were analyzed using the UV photolysis model and the results of deposition experiments carried out as a function of TMA pressure P and the distance between the irradiated gas region and the substrate. The experimental configuration was designed to suppress surface irradiation and photoinduced reactions in adsorbed TMA. The mean free path of the precursor supecies for Al film growth was found to range from 97 to 25m for P0.1-0.5 Torr consistent with the precursors being Al atoms. Auger electron supectroscopy analyses, before and after air exposure, of films deposited at Ts ≤ 200C showed that they were pure porous Al with occluded hydrocarbon supecies. There was no indication of Al-C bonding. Combining these results with the UV photolysis model, we conclude that Al atoms, and not Al (CH3) „ radicals, are the primary precursors for Al film growth and that deposition occurs simply by the diffusion of gas-phase photogenerated Al atoms to the surface.
AB - Mechanisms for the UV photolytic deposition of Al by KrF irradiation of trimethylaluminum (TMA) in ultrahigh vacuum have been investigated. Based upon optical emission supectra combined with molecular orbital calculations, a model for the UV photolysis of dimerized TMA, A12(CH3)6, was developed in which Al and CH3were produced through cascade one-photon absorption processes in A12(CH3)6and A1(CH3)n(n 1, 2, 3). In addition, time-resolved fluorescence measurements showed that CH was also generated in the gas phase by a photolytic side reaction involving photofragments of TMA. Film growth kinetics were analyzed using the UV photolysis model and the results of deposition experiments carried out as a function of TMA pressure P and the distance between the irradiated gas region and the substrate. The experimental configuration was designed to suppress surface irradiation and photoinduced reactions in adsorbed TMA. The mean free path of the precursor supecies for Al film growth was found to range from 97 to 25m for P0.1-0.5 Torr consistent with the precursors being Al atoms. Auger electron supectroscopy analyses, before and after air exposure, of films deposited at Ts ≤ 200C showed that they were pure porous Al with occluded hydrocarbon supecies. There was no indication of Al-C bonding. Combining these results with the UV photolysis model, we conclude that Al atoms, and not Al (CH3) „ radicals, are the primary precursors for Al film growth and that deposition occurs simply by the diffusion of gas-phase photogenerated Al atoms to the surface.
UR - http://www.scopus.com/inward/record.url?scp=0039747749&partnerID=8YFLogxK
U2 - 10.1116/1.573644
DO - 10.1116/1.573644
M3 - Article
AN - SCOPUS:0039747749
SN - 0734-2101
VL - 4
SP - 3146
EP - 3152
JO - Journal of Vacuum Science and Technology, Part A: Vacuum, Surfaces and Films
JF - Journal of Vacuum Science and Technology, Part A: Vacuum, Surfaces and Films
IS - 6
ER -