Leakage and Reliability Characteristics of Lead Zirconate Titanate Thin‐Film Capacitors

Abstract

Resistance degradation in lead zirconate titanate (Pb(Zr,Ti)O 3 , PZT) thin‐film capacitors has been studied as a function of applied voltage, temperature, and film composition. The mean time‐to‐failure (lifetime, or t f ) of the capacitors shows a power‐law dependence on voltage of the form t f ∝ V −n ( n similar/congruent 4‐5). The capacitor lifetime also exhibits a temperature dependence of the form t f ∝ exp[ E a /( kT )], with an activation energy of 0.6‐1.0 eV. The steady‐state leakage current in these samples seems to be bulk controlled. The voltage V , temperature T , and polarity dependence of the leakage current collectively suggest a leakage‐current mechanism that is most similar to a Frenkel‐Poole process. The t f value and the leakage current of niobium‐doped PZT films are superior to those of undoped PZT films. This result can be explained on the basis of the point‐defect chemistry of the PZT system. Finally, the results indicate that the niobium‐doped PZT films meet essential t f requirements for decoupling‐capacitor applications.