Effect of Thermal Annealing on the Electrical Properties of Thin ZrO2 Layers

Abstract

The electrical properties of Al/ZrO2/SiO2/Si Metal-Insulator-Semiconductor (MIS) structures with ZrO2 layer fabricated by radio frequency sputtering followed by thermal annealing at 600 ºC or 850 ºC in O2 are studied. The high frequency C-V curves of all MIS structures demonstrate counter clockwise hysteresis due to charging from the top electrode. The samples annealed at 850 ºC have larger hysteresis window, probably due to formation of polycrystalline structure. At negative voltage Poole-Frenkel emission is the dominant transport mechanism through the ZrO2/SiO2 dielectric, while at positive voltage up to current density of ~3x10-8 A/cm2 the current limiting mechanism is Fowler-Nordheim tunneling in the SiO2 conduction band. At higher current density again Poole-Frenkel emission is the dominant transport mechanism.