Thickness Dependence of the Time Dependent Dielectric Breakdown Characteristics of Pb(Zr, Ti)O3 Thin Film Capacitors for Memory Device Applications

The time dependent dielectric breakdown characteristics of lead zirconate titanate [Pb(Zr0.53Ti0.47)O3] (PZT) thin film capacitors are studied as a function of film thickness. The thickness of PZT films ranges from 70 nm to 470 nm. The variation of leakage current with electric field can be described by a power law relationship. A power law can also describe the relation between the time to dielectric breakdown (t BD) and the electric field. The exponent of the first power law agrees very well with the second when the leakage current is measured using a short delay time of 0.1 s. An extrapolation method was used to extract the t BD lifetime by correlating the t BD and the leakage current. The value of t BD lifetime increases from 104 s to 1012 s as the film thickness is decreased from 470 nm to 70 nm. If the leakage current is measured using a longer delay time (>0.1 s), stress degradation of the samples is observed.