Properties of ferroelectric thin film capacitor for embedded passive applications

BaTiO₃/Ba_0.6Sr_0.4TiO₃/SrTiO₃ (BT/B ST/ST, as one periodic structure) multilayer thin films were deposited on Pt/Ti/SiO₂/Si substrates by a sol-gel method. Platinum electrodes were then patterned on the films by sputtering and lithographic process to form metal-ferroelectric-metal (MFM) capacitors. The multilayer thin films were crack free, compact and crystallized in perovskite structure. The crystallization temperature was between 600°C and 650°C. The dielectric constant of the multilayer films was significantly higher than that of individual uniform films of BaTiO₃, SrTiO₃ or Bao₆Sro₄TiO₃ of similar thickness. The multilayer thin films showed excellent dielectric and electric properties that make them promising candidates for the dielectric layer of embedded capacitor in package substrate in a discrete format. Within the entire test range of frequencies, the capacitance of all samples remained at the level of several nF. The breakdown voltage of the MFM capacitors was measured to be greater than 27 V.