Effects of annealing temperature on ultra-low dielectric constant SiO2 thin films derived from sol-gel spin-on-coating

The results of ultra-low dielectric constant (k) SiO₂ films, derived from sol-gel spin-on-coating process using a combination of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) (mole ratio of TEOS:MTES=4:1), have been reported. The effects of post deposition annealing temperature (300-500 °C for 30 min in argon ambience) on the physical, chemical, and electrical properties of the oxide have been systematically investigated. Filmetric system, Fourier transform-infrared spectroscope, X-ray diffraction system, atomic force microscope, and field-emission scanning electron microscope with energy dispersive X-ray have been employed for physical and chemical analyses. Electrical property of the oxide, in terms of leakage current through the oxide, has also been investigated. The oxide, annealed at 500 °C, produced the lowest dielectric constant value (k=2.3) and the lowest leakage current with no obvious oxide breakdown. The explanation of this observation has been discussed.