Use of anodic tantalum pentoxide for high-density capacitor fabrication

In this work we report on very thin (10 to 100 nm) tantalum oxide fabricate d by anodic oxidation of tantalum nitride and tantalum silicide to be used as the dielectric of high density MIM and MIS capacitors. These films exhib it greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Several c ounter and bottom electrodes have been used and compared. The effects of th e different processing conditions (top-electrode metals, annealing conditio ns, bottom electrode stoichiometry) on the capacitor performances are exten sively discussed throughout this work. The nitrogen content of tantalum nit ride films seems to have an important influence on the insulator quality. L eakage currents in the insulator have been carefully studied in order to de termine the nature and physical origin of the dominant conduction mechanism s in the insulator. The electrical behaviour of the resulting high-density MIM capacitors has been extensively characterized. Finally, we describe a n ew method to fabricate MIS diodes with anodic tantalum oxide as insulator.