Progress in the developments of (Ba,Sr)TiO₃ (BST) thin films for Gigabit era DRAMs

This paper reviews the recent developments of (Ba,Sr)TiO₃ (BST) thin films for future Gbit era dynamic random access memory (DRAM) applications. The trends of DRAM capacitors in the last decade are briefly described first. Then the technological aspects of BST films such as deposition techniques, post-annealing, physical, electrical and dielectric characteristics of the films, effects of electrode materials, dielectric relaxation and defect analysis and the reliability phenomena associated with the films are briefly reviewed with specific examples from recent literature. The basic mechanisms that control the bulk electrical conduction and the origin of leakage currents in BST films are also discussed. Finally, possible developments of gigabit era DRAM technology are summarized.