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

Abstract

High-pressure H 2 O 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 ×10 6 Pa H 2 O 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 ×10 17 (as deposited) to 1.4 ×10 15 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 ×10 6 Pa-H 2 O 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 /SiO 2 double layered structure formed by the combination of thermal evaporation and heat treatment with high-pressure H 2 O vapor.