The Lanio <sub> 3 </ Sub> Electrodes And Layered Bi-based Ferroelectric Thin Film Properties

Ferroelectric material is a kind of functional material, besides its ferroelectricity,it has many special properties such as high dielectric permittivity , piezoelectricity ,pyroelectricity , electrooptics and so on, and can be utilized in various devices such asHigh-K material in capacitors, acoustic wave devices, piezoelectric sensors, MEMs,thermal detector and electroopic devices. Therefore research and development effortin ferroelectric materials and devices have now hit a feverish pitch. Many universitylaboratories, national laboratories, and advanced R﹠D laboratories of large ICmanufacturer are deeply involved in the pursuit of ferroelectric device technologies.With the developing of ferroelectric thin film fabrication technology, especially theintegration of ferroeletric thin film onto a CMOS silicon chip, one great step wasmade along the road of the application of ferroelectrics. Now the most important areas of applications of ferroelectrics are DRAM andembedded memory. One of the most significant phenomena of the past decade in thefield of semiconductor memories has been the explosive growth of the non-volatilememories market, driven by cellular phones and other types of electronic portableequipment (mobile PC, mp3 audio player, digital camera, and so on). Portablesystems are demanding non-volatile memory at increasing density with very highwriting throughput for data storage application. FERAM (ferroelectric random accessmemory) can meet these needs pretty well, with its high reading and writing speed,low voltage operation, much longer retention time, and much greater write cycleendurance. Whereas it can also find its utilization in military,satellite and aircraftwith its special property of radiation hardness. Dramatic developments were made in the technology of ferroelectric memory inthe past tens of years. Many materials have been investigated so far, but the mostsuitable materials for FERAM are PZT,SBT and BLT. Its integration density wasgreatly improved from original 4Kbit to 4Mbit, with its cell structure developmentfrom 8T-2C,2T-2C to 1T-1C. And according to VLSI 2002, Samsung announced thatthey had made a 32Mbit FERAM using 1T-1C cell structure. There is now aconsiderable optimism that ferroelectric devices and products will occupy asignificant market-share in the future. In this paper, the major purpose is to investigate the fabrication and processingtechnologies of ferroelectric thin film for the application in non-volatile memory. TheAbstractproperty of PZT capacitor was investigated, and through the utilization of conductingmetallic electrode LaNiO3(LNO), anti-fatigue property of PZT capacitor was greatlyimproved; the fabrication and property of Bi-layered ferroelectrics was investigated;MFS and MFIS capacitor were fabricated with BLT as the ferroelectric material, andtheir properties were studied. The major creative ideas in the paper are as follows:1,Preparation of the capacitor with the structure of Au(Cr)/PZT/LaNiO3/SiO2 , whose leakage current was very small , and great difference had been got between its polarization-switching current and non-switching current. The negative resistance was observed which was due to the back-switching of ferroelectric domain. And considering the asymmetry of the hysteresis curve, it can be concluded that internal electric field,strain and non-180°ferroelectric domain were the main reasons for the negative resistance and the asymmetry of the hysteresis curve.2,An improved Sol-Gel processing method was put forward, and much better orientation property , leakage property and ferroelectric property of SBTi(SrBi4Ti4O15) and BLT(Bi3.25La0.75Ti3O12) capacitors were obtained based on this method. Fatigue free SBTi and BLT capacitor were fabricated, and they also had good retention property. With Bi4Ti3O12 thin film as seed layer, the crystallization temperature of SrBi4Ti4O15 thin film was successfully reduced...