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 dielectri c BST capacitors. Ir was found to be superior to Pt in a number of asp ects such as resistivity, adhesion and surface roughness. The Pt/BST/I r/SiO2/Si capacitors showed leakage currents as low as Pt/PST/Pt/SiO2/ Si ones, but higher capacitance resulted. For endurance properties wit h +5V unipolar pulse trains, the dielectric constant of BST films on I r 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 bott om electrode effects on BST film properties were well explained by the formation of IrO2 phases on the surface of Ir electrodes.