Photolithographic deposition of insulating Al2O3 films from thin amorphous films of aluminum complexes on silicon surfaces

The photochemical metal organic deposition reactions of amorphous films of aluminum p-diketonates and mixed aluminum alkoxide beta -diketonates on silicon surfaces are presented. The precursors, Al(EtOacac)(3) [EtOacac= OC(OCH2CH3)CHC(CH3)CO], Al(acac)(3) [acac = OC(CH3)CHC(CH3)CO], Al(EtOacac)(2)OBu [Bu = CH(CH2CH3)CH(3)l, Al(EtOacac)(OBu)(2) and Al(EtOacac)(OPr)(2) [Pr = CH(CH3)(2)], were deposited as amorphous thin films by spin coating. The photochemistry of these films was monitored by FTIR spectroscopy. The photolysis with 254-nm light led to the loss of the ligands from the film. The films composed of Al(EtOacac)(3), Al(acac)(3), Al(EtOacac)(2)OBu, Al(EtOacac)(OBu)(2) and Al(EtOacac)(OPr)(2) reacted with half-lives of 20, 180, 40, 60 and 300 min, respectively, and yielded X-ray amorphous aluminum oxide films. The thin film products were analyzed by Auger electron spectroscopy. Only the two complexes, Al(EtOacac)(2)OBu and Al(EtOacac)(OBu)(2), yielded impurity-free Al2O3. The remaining complexes produced films contaminated by organic materials thought to arise from the ligands. This process was then used to lithograph patterns on silicon surfaces. A feature size of 2 mum was demonstrated. (C) 2000 Elsevier Science S.A. All rights reserved.