SURFACE-CHEMISTRY OF AL2O3 DEPOSITION USING AL(CH3)(3) AND H2O IN A BINARY REACTION SEQUENCE

Sequential surface chemical reactions for the controlled deposition of Al2O3 were studied using transmission Fourier transform infrared (FTIR) spectroscopy. A binary reaction for Al2O3 chemical vapor deposition (2Al(CH3)(3)+3H(2)O--> Al2O3+6CH(4)) was separated into two half-reactions: (A) AlOH+Al(CH3)(3)-->Al-O-Al(CH3)(2)+CH4; (B) Al-O-Al(CH3)(2) +2H(2)O-->Al-O-Al(OH)(2)+2CH(4). The trimethylaluminum [Al(CH3)(3)] (TMA) and H2O reactants were employed alternately in an ABAB... binary reaction sequence to achieve controlled Al2O3 deposition. FTIR analysis of these surface reactions was performed in situ in an ultrahigh vacuum (UHV) chamber using high surface area alumina membranes. The AlOH and AlCH3 surface species were monitored by the infrared absorbance of the AlO-H stretching vibrations between 3800 and 2600 cm(-1) and the AlC-H-3 stretching vibrations between 2942 and 2838 cm(-1). The optimal conditions for controlled Al2O3 growth were observed using TMA and H2O exposures at 0.3 Torr on substrates at 500 K. The spectra revealed that both the (A) and (B) reactions were self-limiting and complete. The thermal stabilities of the AlOH and Al(CH3)(chi) surface species on alumina were also measured versus annealing between 300 and 900 K. In addition, the deposition of amorphous Al2O3 thin films was demonstrated on Si(100) using the ABAB... binary reaction sequence.