Abstract
The recent trend of FRAM (Ferroelectric Random Access Memory) including Y1 (Bi2SrTi2O9) is reviewed with special reference to crystal structure, spontane ous polarization, ferroelectric hysteresis loop, memory-cell structure, and vari ous methods for synthesizing ferroelectric thin films. The size effect, induced by grain size, domain structure, crystal structure, soft mode, and other factors, is discussed based on the data of powder ceramic processing. Further, nearly size effect-free ferroelectric thin films obtained by artificial superlattice oxides are introduced. To obtain a high performance FRAM as a ferroelectric non volatile memory, it is indispensable to accomplish (i) the enhancement of ferro electricity, (ii) the improvement of fatigue, and (iii) the microstructural control of cell structure with 1 transistor/1 capacitor.
