Bismuth-zinc-niobate embedded capacitors grown at room temperature for printed circuit board applications

We fabricated metal-insulator-metal (MIM) thin film capacitors with ${\mathrm{Bi}}_{1.5}{\mathrm{Zn}}_{1.0}{\mathrm{Nb}}_{1.5}{\mathrm{O}}_7$ (BZN) dielectric films. The BZN films were deposited at room temperatures by pulsed laser deposition and annealed below $200°\mathrm{C}$ which is compatible with the used polymer-based substrates. The dielectric constant of BZN films increases from 2 to 70, when they are annealed at $150°\mathrm{C}$ , but still in amorphous phase. We found that a considerable portion of Bi metallic phase still remains in the as-deposited film. They turn into oxides upon annealing at $>120°\mathrm{C}$ , causing the dramatic change of the dielectric properties. Amorphous BZN thin films exhibit superior dielectric characteristics, capacitance density of $150\mathrm{nF}∕{\mathrm{cm}}^2$ , and leakage current less than $1\mu \mathrm{A}∕{\mathrm{cm}}^2$ at $5\mathrm{V}$ . The MIM capacitors using amorphous BZN thin films will be a promising candidate for the PCB-embedded capacitors.