(BaSr)TiO3 thin films with conducting perovskite electrodes for dynamic random access memory applications

Interfaces and hence electrodes determine the performance of (Ba,Sr)TiO3 (B ST) capacitors for ultralarge scale integration dynamic random access memor ies. Electrode materials forming a rectifying contact on BST drastically re duce the dielectric constant and hence the capacitance and charge storage d ensity of the capacitor, when the dielectric thickness is reduced. This can limit the role of Pt as an electrode material for gigabit dynamic random a ccess memories (DRAM). The conducting oxide, La0.5Sr0.5CoO3 (LSCO) with its perovskite structure, has structural and chemical compatibility with BST. Our results in LSCO/BST/LSCO capacitor show that the mechanism of conductio n is not interface limited but predominantly bulk limited. A 75 nm BST film with LSCO electrodes shows a leakage current density of 1 X 10(-7) A/cm(2) at 1 V, 85 degrees C. The dielectric constant at 1 V, 10(5) Hz is 350, mak ing LSCO a potential contact electrode for DRAM memories. (C) 1999 American Institute of Physics. [S0003-6951(99)00821-9].