The effect of deposition temperature on the material and electrical properties of PZT thin films for ULSI DRAM applications

Abstract

The effects of deposition temperature on the properties of thin films of sputtered lead-zirconate-titanate (PZT) have been studied for ULSI DRAM storage capacitor dielectric applications. The films were deposited by reactive dc magnetron sputtering from a multi-component target. The grain size for the films deposited at 400°C was found to be less than 1000 Å, while it was ～ 10–30 μm for films deposited at 200°C. Small grain-sized material is desirable since it leads to better cell-to-cell uniformity in terms of charge storage capacity and other electrical and reliability properties. The optimum lead compensation was found to increase as the deposition temperature (T _dep) increased. Leakage current density stays fairly constant as T _dep is varied. As-deposited films, with a deposition temperature of 500°C, were rich in the perovskite phase and showed a high charge storage density of 11.2 μC/cm² and a low leakage current density of 5.1 × 10^?7 A/cm² (both at 1.5 V). This implies the possibility of eliminating the high temperature crystallization-annealing step.