Improvement Of Ferroelectric Properties Of PZT Thin Films

PZT films have excellent electrical properties,which have a wide range of applications in microelectronics,microelectromechanical and other fields.Among them,the use of PZT thin film production of ferroelectric random access memory（FRAM）in recent years has attracted the many researchers and manufacturers.But because of the characteristics named of ferroelectric fatigue in PZT thin film,its further development in the field of ferroelectric memory is limited.In this paper,we have explored the method of improving the ferroelectric fatigue properties of PZT thin films,hoping to further promote the progress of PZT thin films in storage applications.Based on the research of PZT thin films in the past,PZT films were prepared by sol-gel method.The causes of ferroelectric fatigue of PZT films were studied.The A-site or B-site donor doping and LNO electrode to replace the traditional Pt bottom electrode method were used to improve the dielectric properties,ferroelectric properties and ferroelectric fatigue properties of PZT film.In this paper,La and W elements were used as donor-dopants in PZT thin films.The experimental results show that the La or W element can significantly improve the dielectric properties,ferroelectric properties and ferroelectric fatigue performance.The optimum concentration of La-doped PLZT film is 2mol%,while the dielectric properties,ferroelectric properties and ferroelectric fatigue properties of the W-doped PZTW thin film increase with the increase of doping concentration,1mol%of the doped PZTW film have the best performance.In this paper,we investigated the effect of different La/Ni ratio on LaNi_xO_3+δfilms.We found that the optimum annealing temperature for the preparation of LNO thin films by sol-gel method was 700℃.At this temperature,LaNi_0.9O thin film with La/Ni ratio of 1:0.9 has a minimum resistivity.The use of LNO thin film instead of Pt as the bottom electrode of PZT thin film can significantly improve the ferroelectric properties of PZT thin film.The PZT thin film with LN_0.9O thin film as the bottom electrode can have good ferroelectric fatigue performance and a smaller threshold voltage in the nonlinear I-V characteristic.Therefore,LN_0.9O thin film is a more suitable alternative electrode material to PZT thin films.