High-density BaTiO3–Cu composite films with optimized BaTiO3 matrix for embedded capacitors

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Abstract To improve dielectric properties and areal capacitance according to percolation theory, 0 to 50 wt% of Cu was used as a metal filler in a BaTiO 3 (BT) matrix. BT–Cu composite films with a thickness of approximately 2 μm were fabricated using aerosol deposition at room temperature for application in embedded-film capacitors. The flow conditions of the carrier gas were varied to fabricate very compact composite thin films without surface craters and internal pores to obtain a high dielectric constant, low dielectric loss, and low leakage current. The BT–Cu composite films displayed highly dense microstructures and smooth surfaces, and good dielectric properties were observed when the carrier gas was supplied at 10 L/min. The dielectric constant of the composite films increased with the increase in Cu content. Although the dielectric loss and leakage current also increased with the increase in Cu content, they were within the allowable limits until the Cu concentration reached 40 wt% in the composite film, and the 40 wt% of Cu contained films showed high areal capacitances that were approximately five times the values reported in previous studies. In addition, a percolation threshold was observed in the composite film with 45 wt% Cu. Despite the appearance of this percolation threshold, the BT–Cu composite films all revealed low frequency dependence because the formation of micro-capacitor structures dominated their interiors.