The planar anodic Al₂O₃-ZrO₂ nanocomposite capacitor dielectrics for advanced passive device integration

The need for integrated passive devices (IPDs) emerges from the increasing consumer demand for electronic product miniaturization, thus requiring packaging to be space- and weight-efficient. Metal-insulator-metal (MIM) capacitors are vital components of IPD systems. Developing new materials, technologies, and assembly techniques is essential for advancing capacitor characteristics and making them suitable for co-integration with other electronic passives. Here, we have created an innovative electrochemical technology combined with the sputter-deposition of Al and Zr metal layers to synthesize novel planar nanocomposite metal-oxide dielectrics consisting of ZrO2 nanorods self-embedded into the nanoporous Al2O3 matrix such that the alumina pores are entirely filled with zirconium oxide. The technology was utilized for assembling MIM capacitors, which were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, electrochemical impedance spectroscopy, and electrical/dielectric measurements at various frequencies and temperatures. In the thickness range of 95–480 nm, the best-achieved and highly competitive MIM device characteristics are the one-layer capacitance density of 112 nF·cm−2, the loss tangent of 4·10−3 at frequencies up to 1 MHz, the leakage current density of 40 pA·cm−2, the breakdown field strength of up to 10 MV·cm−1, the energy density of 100 J·cm−3, the quadratic voltage coefficient of capacitance of 4 ppm·V−2, and the temperature coefficient of capacitance of 480 ppm·K−1 at 293–423 K at 1 MHz. The outstanding performance, thermal stability, and tunable capacitor characteristics allow for their application in low-pass filters, coupling/decoupling/bypass circuits, RC oscillators, energy storage devices, ultrafast charge/discharge units, or high-precision analog-to-digital converters. The technology for thin-film capacitors based on the non-porous planar anodic-oxide dielectrics complements, for the first time, the electrochemical conception of IPDs that, until now, combined the anodized multilevel aluminum interconnection, microresistors, and microinductors, all co-related in one system for use in future portable electronic devices.