Reliability of Sol-Gel Derived Ferroelectric Memories
Final rept. Jan 1989-31 May 1992
ARIZONA STATE UNIV TEMPE
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A process was developed to prepare PZT5248 precursor solutions. Five spin-on depositions of this solution 0.5M were necessary to grow 0.5 micron thin films of polycrystalline PZT onto PT passivated silicon wafers. An addition of 15 excess Pb0 aided the densification process. Films derived from l.5M solutions resulted in PZT films of equivalent thickness in only two depositions. Dielectric constant and tan Sigma were 800 and 2 respectively, at 1 kHz. Remnant and saturation polarizations were 12 and 25 micron Ccm2, respectively. Coercive fields of 36-48 kvcm were measured. From retention experiments, a polarization loss of 11.2 after 3.2 years was estimated i.e., the switched charge would diminish from 5.8 to 5.2 ACCM2. High frequency pulse fatigue data on Nb and Sn modified PZT showed a reduction of the switched charge of 26 after 4x,10 12 polarization reversals.
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