T(8)-HYDRIDOSPHEROSILOXANES - NOVEL PRECURSORS FOR SIO(2) THIN-FILMS .1. PRECURSOR CHARACTERIZATION AND PRELIMINARY CVD

High-quality SiO2 thin films were deposited from the novel precursor T8-hydridospherosiloxane [H8Si8O12]. Films were specular, smooth, amorphous, stoichiometric SiO2. The T8-hydridospherosiloxane precursor was characterized in terms of its volatility and decomposition properties. The precursor was volatile (1-100 mTorr) and thermally stable over 80-140-degrees-C and has an enthalpy of vaporization of 78 kJ/mol. Decomposition of T8 in an O2 environment was initiated at 250-degrees-C and completed by 350-degrees-C at a decomposition time of 30 min. The CVD experiments were carried out in a hot-wall reactor. Source temperature was 80-degrees-C, deposition temperatures ranged from 450 to 525-degrees-C, carrier gas was 10 sccm O2, chamber pressure was 10 Torr, and substrate was [100] p-type Si wafer. Film characterization techniques included XRD, FTIR, ellipsometry, AES, ESCA, and SEM. Volatility was characterized by isothermal TGA experiments. The precursor was heated in a vertical tube furnace with a N2 Purge rate of 25 mL/min. Vapor pressure was calculated using gas diffusion equations. Thermal decomposition experiments were carried out in quartz flasks which were sealed under an O2 environment. Products of decomposition were examined by Si-29 solid-state NMR and FTIR.