Iridium thin film as a bottom electrode for high dielectric (Ba,Sr)TiO3 capacitors

We propose Ir thin films as new electrode materials for high dielectric BST capacitors. Ir was found to be superior to Pt in a number of aspects such as resistivity, adhesion and surface roughness. The Pt/BST/Ir/SiO 2 /Si capacitors showed leakage currents as low as Pt/BST/Pt/SiO 2 /Si ones, but higher capacitance resulted. For endurance properties with +5V unipolar pulse trains, the dielectric constant of BST films on Ir decreased by only 10% below its initial value after switching of 10 9 cycles while that on Pt degraded by 30% after 10 8 cycles. Ir bottom electrode effects on BST film properties were well explained by the formation of IrO 2 phases on the surface of Ir electrodes.