La(sub 0.5)Sr(sub 0.5)CoO(sub 3) electrode technology for Pb(Zr, Ti)O(sub 3) thin film nonvolatile memories

摘要

Oxide electrode technology is investigated for optimization of Pb(Zr,Ti)O(sub 3) (PZT) thin film capacitor properties for high density nonvolatile memory applications. PZT thin film capacitors with RF sputter deposited La(sub 0.5)Sr(sub 0.5)CoO(sub 3) (LSCO) electrodes have been characterized with respect to the following parameters: initial dielectric hysteresis loop characteristics, fatigue performance, microstructure and imprint behavior. Our studies have determined that the fatigue of PZT capacitors with LSCO electrodes is less sensitive to B site cation ratio and underlying electrode stack technology than with RuO(sub 2) electrodes. Doping PZT thin films with Nb (PNZT) improves imprint behavior of LSCO//PZT//LSCO capacitors considerably. We have demonstrated that PNZT 4/30/70 // LSCO capacitors thermally processed at either 550(degrees)C or 675(degrees)C have almost identical initial hysteresis properties and exhibit essentially no fatigue out to approximately 10(sup 10) cycles.