Suppression of Leakage Current of Deposited SiO2 with Bandgap Increasing by High Temperature Annealing

Abstract

In this work, we suppressed the leakage current of chemical-vapor-deposited SiO2 films using tetraethylorthosilicate (TEOS-SiO2) by high temperature annealing. As a result of annealing, leakage currents of TEOS-SiO2 were suppressed to the level of thermally grown SiO2. Meanwhile, the relationship of electrical and structural characteristics of TEOS-SiO2 has been investigated to reveal the mechanism of the improvement of the dielectric properties with thermal annealing. Stress relaxation of the TEOS-SiO2 caused by thermal annealing was observed as blue shift of the infrared absorption spectral peak with a Fourier-transform infrared attenuated total reflection (FT-IR-ATR). It was concluded that the stress relaxation increased the bandgap of TEOS-SiO2, resulting in suppression of the leakage current. The roughness of the TEOS-SiO2 surface was also investigated by atomic force microscopy (AFM). Additionally, thermal desorption spectroscopy (TDS) was performed to understand the phenomena during film densification by thermal annealing.