Mixed Al and Si doping in ferroelectric HfO_2 thin films

摘要

Ferroelectric HfO_2 thin films 10 nm thick are simultaneously doped with Al and Si. The arrangement of the Al and Si dopant layers within the HfO_2 greatly influences the resulting ferroelectric properties of the polycrystalline thin films. Optimizing the order of the Si and Al dopant layers led to a remanent polarization of ～20μC/cm~2 and a coercive field strength of ～1.2MV/cm. Post-metallization anneal temperatures from 700 ℃ to 900 ℃ were used to crystallize the Al and Si doped HfO_2 thin films. Grazing incidence x-ray diffraction detected differences in peak broadening between the mixed Al and Si doped HfO_2 thin films, indicating that strain may influence the formation of the ferroelectric phase with variations in the dopant layering. Endurance characteristics show that the mixed Al and Si doped HfO_2 thin films exhibit a remanent polarization greater than 15μC/cm~2 up to 10~8 cycles.