Thickness and Temperature Dependence of Dielectric Reliability Characteristics in Cerium Dioxide Thin Film

The thickness and temperature dependence of the CeO₂ dielectric reliability characteristics of metal-oxide-semiconductor capacitors is studied. The dielectric breakdown strength (E_bd) of CeO₂ thin films decreases with increasing temperature. The Weibull slope of the charge-to-breakdown (Q_bd) statistics is a function of the dielectric thickness. However, it is independent of temperature. In this work, the Weibull slope was calculated by the method of maximum-likelihood estimation. At room temperature, the Weibull slopes with thicknesses of 7.3, 11.2, and 13.1 nm are about 1.57, 3.28, and 4.41, respectively. According to a cell-based analytic model, the effectively stress-induced defect size (a₀) in CeO₂ in the breakdown event was determined to be about 1-2 nm. Therefore, the capture cross section of the generated defects is on the order of 10^-14 cm², which indicated that the defects were neutral centers. In addition, a comparison with SiO₂- and HfO₂-gated capacitors was made.