Passivation of SiO2/Si Interfaces Using High-Pressure-H2O-Vapor Heating

High-pressure H2O vapor heating was used for the passivation of silicon surface. The thermally evaporated SiO x films formed on the silicon surface was oxidized and Si–O bonding density increased with an activation energy of 0.035 eV with increasing heating temperature upon heat treatment with 1.0 ×106 Pa H2O vapor. The peak wave number and full width at half maximum of the Si–O absorption band due to the Si–O–Si antisymmetric stretching vibration mode were changed to 1077 cm-1 and 72 cm-1, respectively. The density of silicon dangling bonds was reduced from 2.0 ×1017(as deposited) to 1.4 ×1015 cm-3 by heat treatment. The effective surface recombination velocity of the p-type silicon wafer that was coated with SiO x films was markedly reduced from 405 cm/s (as deposited) to 13 cm/s by heat treatment with 2.1 ×106 Pa-H2O vapor at 260°C for 3 h. The interfaces retained the low recombination velocity 8000 h after keeping the sample in air. Effective field effect passivation was demonstrated using a SiO x /SiO2 double layered structure formed by the combination of thermal evaporation and heat treatment with high-pressure H2O vapor.