Mixed Phase Thin Film Capacitor
This invention describes a method for the fabrication of a thin-film capacitor with high dielectric constant and low leakage. It relies on special methods of depositing the dielectric material to achieve both a high dielectric constant and low leaka ge current and is useful in applications that require large capacitances with small size. It combines PZT with BaTiO3 layers to take advantage of the superior electrical properties of the BaTiO3 structure, while enhancing the electrical properties of PZT. Specifically, ferroelectric PbZrxT1-xO3 (PZT) thin films are deposited on Pt coated Si substrates by using RF magnetron sputtering. A method for obtaining desirable stoichiometric PZT, that is the desired ferroelectric perovskite phase, infusing the same with better dielectric properties through a Pb/(Zr+Ti) ratio of 1.2 and depositing at 350 degree C followed by thermal treatment at 620 degree C for 30 min, is disclosed. The structural and electrical properties of the PZT layer wer e further improved by a method of fabricating a novel multi-layer structure that combines the PZT thin film with nanolayers of BaTiO3. The method and device of the present invention provided reduced leakage current density while maintaining high rela tive dielectric constants.
Categories: Materials & Chemicals, General Engineering Patents Issues: 5,978,207 6,340,621
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