Embedded thin film capacitors-theoretical limits

The large physical size of capacitors and/or excessive values of associated lead inductance are two major limitations in the development of novel packaging modules, with high packaging density, high performance and reliability along with low system cost. Embedded capacitor technology in thin film form offers a promising solution to these limitations. A design space with capacitance density and breakdown voltage as performance properties, with material dielectric constant and film thickness as parameters has been explored, focusing on tantalum pentoxide (Ta₂O₅) as the dielectric material. An inherent tradeoff is established between breakdown voltage and capacitance density for thin film capacitors. The validity of the proposed design space is illustrated with thin films of Ta₂O₅, showing deviation from the "best can achieve" breakdown voltage for films thinner than 0.4 μm and films thicker than 1 μm.