Low equivalent oxide thickness metal/insulator/metal structures for DRAM application

Abstract

We have prepared metal/insulator/metal (MIM) structures with RuO₂ bottom electrode and TiO₂ dielectric film for advanced dynamic random access memory (DRAM) technology. RuO₂ films were grown by metal organic chemical vapour deposition while TiO₂ films were prepared by atomic layer deposition. RuO₂ bottom electrode crystallizes in rutile structure and induces growth of rutile TiO₂. Equivalent oxide thickness (EOT) as low as 0.39 nm and dielectric constant as high as 130 was obtained. It was found that leakage current strongly depends on either oxygen treatment after deposition or its admixture to the carrier gas during TiO₂ deposition. However, MIM structures under study show higher leakage current that is expected for the application (~10^-7 A/cm²) in DRAM technology.