LEAKAGE AND RELIABILITY CHARACTERISTICS OF LEAD-ZIRCONATE-TITANATE THIN-FILM CAPACITORS

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 (lifetim e, or t(f)) of the capacitors shows a power-law dependence on voltage of the t(f) proportional to V-n (n approximate to 4-5). The capacitor lifetime also exhibits a temperature dependence of the form t(f) propo rtional to 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 control led, The voltage V, temperature T, and polarity dependence of the leak age current collectively suggest a leakage-current mechanism that is m ost 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 P ZT films, This result can be explained on the basis of the point-defec t chemistry of the PZT system, Finally, the results indicate that the niobium-doped PZT films meet essential t(f) requirements for decouplin g-capacitor applications.