Introduction of selectively nucleated lateral crystallization of lead zirconate titanate thin films for fabrication of high-performance ferroelectric random access memory

We found that large single grains of lead zirconate titanate (PZT) thin film of which grain size was as large as 40 mum in length could be fabricated by lateral crystallization from the seeds. The seeds were prepared on the Pt substrate in the form of crystallized PZT dots. The electrical characteristics of PZT thin films (Pt/PZT/Pt structure) obtained by selectively nucleated lateral crystallization (SNLC) were found to be superior to those of polycrystalline PZT thin films. PZT thin films obtained by SNLC showed a leakage current density of 8 x 10(-8) A/cm(2), a breakdown field of 1240 kV/cm, a saturation polarization of 42 muC/cm(2), and a remanent polarization of 30 muC/cm(2). No degradation of the electrical properties was observed even after 2 x 10(11) cycles using 1 MHz square wave form at +/- 10 V. Retention test revealed no appreciable data loss after 30000 s of memory retention at room temperature.