Ultra-Thin Sputtered Pzt Films for Ulsi Drams

In this work, a high-temperature deposition technique has been developed for ultra-thin sputtered PZT films for ULSI DRAM (<256Mb) storage capacitor applications. In contrast to the previously developed low-temperature (200°C) deposition, deposition at high-temperature (400°C) yields a desirable reduction in grain size of the perovskite phase. The thickness of PZT films has been reduced to less than 30nm with high charge storage density (∼30μC/cm2) and low leakage current density. An optimized 65nm PZT thin film was found to have an equivalent SiO2 thickness of 1.9Å and a leakage current density of less than 10−6 A/cm2 under 2V operation.