Reduction of ∙Si≡Si₃ defect density at the Si/SiO₂ interface by sol-gel SiO₂ thin film passivation

The effect of SiO₂ thin film passivation by sol-gel processes with various acid catalysts, ethanol (EtOH): tetraethyl orthosilicate (TEOS) volume ratios and baking temperatures on the carrier lifetime of the Si surface and Si/SiO₂ interface properties was studied. SiO₂ thin film passivation prepared by H₂SO₄ catalyst with a EtOH:TEOS volume ratio of 10:1 at a baking temperature of 50 °C greatly increased the carrier lifetime on the various Si wafers regardless of dopant type, wafer resistivity and crystal orientation. For example, the carrier lifetime increased from 28 to 316 μs before and after the sol-gel SiO₂ passivation on the Si (100) surface with resistivity higher than 1000 Ω cm. It was confirmed that the increase of carrier lifetime resulted from the significant decrease in the defect density related to the ∙Si≡Si₃ dangling bond at the Si/SiO₂ interface. In the current study, proper sol-gel SiO₂ film passivation increased the carrier lifetime on the Si surface by controlling the formation of ∙Si≡Si₃ defects at the Si/SiO₂ interface.