Electrical and reliability characteristics of lead-zirconate-titanate (PZT) ferroelectric thin films for DRAM applications

The electrical and reliability characteristics of lead-zirconate-titanate (PZT) ferroelectric capacitors are presented. Thin Pb(Zr/sub 0.5/Ti/sub 0.5/)O/sub 3/ films of 350 nm were prepared using a solution-gelatin technique. Hysteresis loop and pulse measurement methods indicate that PZT films exhibit a large charge storage density of 7.3 mu C/cm/sup 2/ and an equivalent dielectric constant of approximately 577. In addition, good endurance behavior (no fatigue or aging wearout after >10/sup 13/ cycles under accelerated unipolar stressing), reasonable transient characteristics (with estimated write time of approximately 0.1 ns and refresh time of approximately 2.5 s), and high effective breakdown field suggest that the PZT ferroelectric material has good potential for applications in advanced DRAMs (dynamic RAMs).<
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