Abstract
Resistance degradation in PZT thin-film capacitors has been studied as a function of applied voltage, temperature, and film composition. It is found that the mean-time-to-failure (life-time or t(f)) of the capacitors shows a power law dependence on applied voltage of the form t(f) proportional to V-n (n similar to 4-5). The capacitor Life-time also (t(f)) exhibits a temperature dependence of the form t(f) proportional to exp(E-a/kT), with an activation energy of similar to 0.8 eV. The steady-state leakage current in these samples appears to be bulk controlled. The voltage, temperature, and polarity dependence of the leakage current collectively suggest a leakage current mechanism most similar to a Frenkel-Poole process. The Nb-doped PZT films exhibit superior life-time and leakage current to the undoped PZT films. This result can be explained based on the point-defect chemistry of the PZT system. Finally, the results indicate that the Nb-doped PZT films meet the essential requirements for decoupling capacitor applications.