Properties of Ferroelectric Memory with Ir System Materials as Electrodes

Naoki IZUMI  Yoshikazu FUJIMORI  Takashi NAKAMURA  Akira KAMISAWA  

IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.4   pp.513-517
Publication Date: 1998/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Memory Devices Using High-Dielectric-Constant and Ferroelectric Thin Films)
ferroelectric thin films,  Pb(Zr,Ti)O3,  FRAM,  fatigue property,  imprint property,  hysteresis,  sol-gel method,  Ir system materials,  STC,  poly-Si plugs,  

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Pb(ZrxTi1-x)O3 (PZT) thin films were prepared on various electrodes. When Ir system materials were used as electrodes, fatigue properties of PZT thin films were improved. Moreover, in the case of the PZT thin film on an Ir/IrO2 electrode, not only fatigue but imprint properties were clearly improved. We could find these improvements were caused by good barrier effect of IrO2 from secondary ion mass spectroscopy (SIMS) analysis. By applying these Ir system electrodes, we fabricated stacked capacitors on polycrystalline silicon (poly-Si) plugs. In spite of high temperature thermal processing, we found poly-Si plugs were ohmically connected with the bottom electrodes of the capacitors from hysteresis measurements and I-V characteristics, and could greatly expect them for practical use.