High dielectric insulators have been widely studied for their application to thin film capacitors. Among these insulators, tantalum oxide ( Ta₂O₅) is an attractive material for VLSI and optoelectronic devices, because of its high breakdown voltage and dielectric constant.

Electrical properties of Ta₂O₅ and Ta₂O₅-based composite films prepared by magnetron sputtering have been investigated in view of their O/Ta ratios, impurities, and micro structures. As additive oxides, Y₂O₃and WO₃ were found to be effective materials for improving insulating properties without decreasing their dielectric constant. Furthermore, measurements of the temperature dependence of the leakage current revealed that the conduction mechanism at RT changed from the Poole-Frenkel type to the Fowler-Nordheim tunneling type by adding Y₂O₃ or WO₃ into Ta₂O₅. Based on the detailed analysis of the results, it is concluded that the addition of Y₂O₃ and WO₃ into the Ta₂O₅ film is effective in the reduction of the defect density without high-temperature annealing and alteration of the electrical conduction mechanism of the films.

�@