Current conduction mechanisms in ZrO2 thin film due to the existance of traps

Abstract

We have studied leakage current characteristics of metal-oxide-semiconductor (MOS) capacitor with Zirconium oxide (ZrO2) for gate dielectric which was grown using atomic layer deposition (ALD) technique. In this work, there are two dominant conduction mechanisms that are responsible for the leakage current. In high electric field region (1.5 ~ 5.0 MV/cm) the dominant mechanism is the space charge limited conduction while the trap assisted tunneling due to the existence of traps in low electric fields (0.8 ~ 1.5 MV/cm). Conduction due to the trap assisted tunneling is found from experimental results of weak temperature dependence of current and the energy level of the trap is obtained. The space charge limited conduction is evidenced, for different temperatures, by the Child’s law dependence of current density vs. voltage. Such a Child’s law dependence can be explained by a single discrete trapping level and we can obtain the activation energy of 0.22 eV.