Resistance degradation of CVD (Ba,Sr)TiO/sub 3/ thin films for DRAMs and integrated decoupling capacitors

Abstract

We have investigated the important failure mechanism of resistance degradation for polycrystalline MOCVD (Ba,Sr)TiO/sub 3/ thin films appropriate for use in DRAMs, as a function of voltage (field), thickness and temperature. At constant field, the measured degradation lifetime decreases with increasing film thickness, resulting from a decrease in the activation energy with respect to temperature for thicker films. Similarly, there are clear indications that thicker films are more field sensitive. Predicted resistance degradation lifetimes obtained from both temperature and voltage extrapolations for DRAM operating conditions of 85/spl deg/C and 1.6 V exceed the current benchmark of 10 years for all the films studied.