SURFACE-CHEMISTRY OF IN2O3 DEPOSITION USING IN(CH3)(3) AND H2O IN A BINARY REACTION SEQUENCE

Sequential surface chemical reactions for the controlled deposition of In2O3 were examined using transmission Fourier transform infrared (FT IR) spectroscopy. In this study, the binary reaction (2In(CH3)(3) + 3H (2)O --> In2O3 + 6CH(4)) was separated into two half-reactions: (A) In OH + In(CH3)(3) --> In-O-In(CH3)(2)* + CH4;(B) InCH3* + H2O --> InOH* + CH4, when the asterisks designate the surface species. The InOH an d InCH3 surface species were monitored by the infrared absorbances of the InO-H and InC-H-3 stretching vibrations. The reactions were therm ally activated and the maximum reaction temperature was limited to 525 K because of trimethylindium (TMIn) pyrolysis. At 525 K, the (A) reac tion saturated after depletion of similar to 60% of the InOH x covera ge. In contrast, the (B) reaction went to completion and was self-limi ting. Despite these observed surface reactions, the growth of conforma l In2O3 films was not achieved on Si(100) at 525 K. Very rough In2O3 f ilms with low growth rates were also observed at 675-775 K in previous studies using InCl3 and H2O in a binary reaction sequence. The therma l stabilities of the InOH and InCH3* surface species were measured fr om 300-900 K. The low coverage of surface species at the various react ion temperatures may explain the rough In2O3 films and low IN2O3 growt h rates.