Enhancement of the dielectric constant of Ta₂O₅through substitution with TiO₂

Abstract

MICROELECTRONICS research is in large part driven by the demand for smaller components with enhanced performance. For capacitive components, which form the basis of many memory devices, the dielectric constant limits the degree of miniaturization—a limit that is now being approached for the materials currently in use. For this reason, exotic compounds with high dielectric constants, such as barium strontium titanate, are being widely investigated¹. But such materials invariably incorporate chemical elements foreign to current microelectronics fabrication procedures, and must pass extensive compatibility tests before they can be used commercially. From a compatibility point of view, tantalum oxide, Ta₂O₅, is considered more promising^2-5 (although its dielectric properties are more modest), and it is known to form high-quality thin films in conventional fabrication processes. Here we show that the dielectric constant of Ta₂O₅ can be increased by nearly a factor of four — from 35 to 126—through the addition of 8% titanium oxide, TiO₂. The minimum area of capacitive components prepared from this material should be reduced by the same factor, and as both tantalum and titanium are compatible with fabrication processes currently in use, the material shows great promise for future microelectronics applications.