Preparation And Properties Of Hafnium Oxide Based Heterojunction By Magnetron Sputtering

Due to the spontaneous polarization of ferroelectrics,the polarization intensity can be reversed when the electric field is applied,which is similar to the high and low levels in memory.With this characteristic,ferroelectric thin films are often used in storage devices,but with the requirements of miniaturization and low power consumption,traditional ferroelectric materials can not meet the current requirements.In 2011,researchers found that Si-doped HfO₂thin films have ferroelectric properties,which started the hot research and preparation of HfO₂-based ferroelectric thin films.Because of it’s pollution-free,high-density integration,which makes up for the shortcomings of traditional ferroelectric materials,it shows a strong vitality.In this paper,the research significance and application of HfO₂-based ferroelectric thin films are described in detail,and the ferroelectric TiN/HfO₂/TiN heterostructure is prepared,and the factors affecting the ferroelectric properties of the structure are explored.The main research contents are as follows:1)TiN thin films were prepared by magnetron sputtering technology.TiN thin films are used as electrode materials in this paper,so they are required to have low resistivity,so as to ensure that the prepared thin films have low leakage current.By changing the process parameters,three aspects of N₂flow rate,deposition temperature and working pressure were studied respectively.The results show that the resistivity of TiN film can be minimized when the N₂flow rate is 3 sccm,the deposition temperature is 300℃,and the working pressure is0.5 Pa.The value is 29.3μΩ·cm,which is close to the resistivity of the bulk 24μΩ·cm.2)Zr:HfO₂thin films were prepared by co-sputtering with Zr sheets attached to Hf targets by radio frequency reactive magnetron sputtering technology.The content of doping elements in Zr:HfO₂under different O₂fluxes was analyzed by XPS.Finally,the TiN/HfO₂/TiN heterostructure was prepared.The leakage current and P-E hysteresis loop were tested with a ferroelectric analyzer.The results show that the prepared samples have better insulation and less leakage current.The HfO₂-based heterojunction,the remanent polarization Pr is about 18μC/cm~2,and the coercive field Ec is about 2 MV/cm.3)The doping elements were changed to Y and Si,and the doped HfO₂-based heterostructure was prepared by the radio frequency reactive magnetron sputtering technology.It was found by GIXRD that after annealing at 700°C,the film had a（111）preferred orientation around 30°,which is believed to be the source of ferroelectricity.The distribution and content of doping elements were tested by XPS and EDS.The results of the ferroelectric tester show that when the Y doping concentration is 5.6 mol.%,the remnant polarization Pr is14.11μC/cm~2,and when the Si doping concentration is 3.3 mol.%,the remanent polarization can reach 14.8μC/cm~2,it shows that the sample has good ferroelectricity.Based on the above research results,a hafnium oxide-based heterojunction with ferroelectricity can be prepared by reactive magnetron sputtering technology,which provides a certain reference for the preparation of hafnium oxide-based heterojunction,which is helpful for the realization of HfO₂ferroelectricity Application of thin films in the field of non-volatile memory storage.