Temperature-Dependent Switching Endurance Of Silicon-doped Hafnium Oxide Ferroelectric Thin Films

Today’s society is an era of information explosion,the exponentially increasing data needs memories with better performance and more reliable operation.At present,the common information storage devices on the market are: read-only memory（PROM,EPROM,etc.）,random access memory（DRAM,SRAM,FeRAM,etc.）,flash memory（NAND / NOR Flash）.Among them,ROM can only read data,erasable programmable ROM is inconvenient to use and has poor integration.Although the new flash memory overcomes the above problems,it has poor reliability and high cost.Ferroelectric random access memory（FeRAM）has become one of the most potential new generation memories because of its good durability,fast reading and writing speed,simple storage unit,low power consumption,high integration and low cost.The stable polarization switching characteristic of ferroelectric materials is the theoretical basis for the implementation of "0,1" binary logic value reading and writing in FeRAM.However,the current development of ferroelectric random access memory has been stagnant,mainly due to the ferroelectric material itself,the thickness leads to large switching voltage and "interference pulse".PZT type ferroelectric thin films,which are commonly used in industry,are difficult to realize device miniaturization due to their complex composition and structure,complex packaging,and poor compatibility with the existing semiconductor technology,resulting in slow progress in the commercialization of ferroelectric random access memory.The HfO₂ based ferroelectric materials in this paper have the remarkable advantages of lead-free,ultra-thin thickness,especially excellent Si-based CMOS integrated process compatibility,so they are rapidly applied to the industrial development of ferroelectric nonvolatile memory devices.In this paper,5 mol% silicon doped hafnium oxide ferroelectric thin films were studied.The evolution of polarization switching behavior of hafnium oxide based thin films under external electric field cyclic loading at room temperature and variable temperature was investigated by using traditional electrical performance tests（hysteresis loop and transient current curve）and calculated the related activation energy.The micro mechanism of polarization behavior evolution of ferroelectric materials is further explored using first-order reversal curve（FORC）diagram — a new method for studying ferroelectric materials.The results show that the distribution of coercivity field and internal bias field in each micro region of ferroelectric thin films and its variation with the cyclic loading of electric field can be described directly by the first-order reversal curve diagrams.Based on the positive/negative internal bias field,the activation energys of wake-up effect are 90.98 ± 6meV and 124.3 ± 8meV,which further verified that the diffusion and migration of oxygen vacancies is the dominant mechanism of wake-up effect.The change of switching density in the first-order reversal curve diagrams at room temperature and variable temperature indicates that the driving force of the split-up phenomenon of the switching current peaks is the internal bias field,which suggests that the main reason for the split-up effect is that the oxygen vacancy enters the switching region from the non-switching region.