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Simple Electrode-Barrier Structure Using Ir for Integration of PZT-Based High-Density Nonvolatile Memories

Published online by Cambridge University Press:  10 February 2011

Kwang B. Lee ,
S. Tirumala ,
Y. Song ,
Sang O. Ryu  and
Seshu B. Desu
Kwang B. Lee
Affiliation:
Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061-0237
S. Tirumala
Affiliation:
Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061-0237
Y. Song
Affiliation:
Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061-0237
Sang O. Ryu
Affiliation:
Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061-0237
Seshu B. Desu
Affiliation:
Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061-0237
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Abstract

We have investigated the electrode-barrier properties of Ir for PZT-based nonvolatile memories. Ir layer was rf-sputtered onto a poly-Si coated Si wafer. PZT thin films were deposited on Ir/poly-Si/SiO2/Si by means of sol-gel spin coating. Highly c-axis oriented perovskite PZT thin films were obtained, which might be due to the interface-controlled growth. We found that Ir in itself acted as an oxygen barrier, which was confirmed from the measurement of P-E hysteresis loops with the electrical contact between top-electrode and bottom-poly-Si. Remanent polarization and coercive field of 1rO2/PZT/Ir/poly-Si capacitor were 20 μC/cm2and 30 kV/cm, respectively and the capacitor showed negligible polarization fatigue up to 1011 switching repetitions. However, the leakage current density at the field of larger than 80 kV/cm was high, which was believed to be related to the unknown phase in PZT caused by the reaction of PbO with bottom-Ir. Such high leakage current behavior could be successively improved by the insertion of vacuum-annealed IrOx buffer layer between PZT/Ir. The electrical properties of IrOx/PZT/annealed-IrO2Ir/poly-Si capacitors are also discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 541: Symposium O – Ferroelectric Thin Films VII , 1998 , 197
Copyright
Copyright © Materials Research Society 1999

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References

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