Effects of thickness scaling on the dielectric properties of Hf0.5Zr0.5O2 ferroelectric thin films

HfO₂-based ferroelectric (FE-HfO₂) thin films have aroused great interests of miniaturizing the integrated ferroelectric devices in the past decade. To construct the scaling rules of the devices, it is necessary to evaluate the scaling laws on several performance aspects of FE-HfO₂ simultaneously. We present a systematic study of thickness scaling effects on the dielectric properties of Hf_0.5Zr_0.5O₂ (HZO) ferroelectric thin films in this work. It is revealed that the degradation of dielectric constant with frequency and the dielectric loss value become faster and larger with decreasing the thickness, respectively. Based on the deep analysis of polarization switching kinetics, we find that the polarization switching speed, fundamentally governed by the grain size, is responsible for the thickness dependence of the evolutions of dielectric responses with frequency. Those results will be the key supplements for constructing the scaling rules of HfO₂-based ferroelectric devices.