Electrical properties of thin film type MLCC with nickel electrodes

The stability and electrical properties of Ni/BaTiO₃(BT)/Ni capacitors were investigated for the preparation of MLCCs by the deposition method. The Ni and BT films were deposited by r.f magnetron sputtering. The electrical resistivities of Ni films before and after annealing were 2.3 and 5.2 × 10^-4 Ω-cm, respectively. The Ni electrode was completely oxidized at 650°C in an O₂ atmosphere, but very stable in an Ar+H₂ atmosphere and in a vacuum. The interdiffusion depth between the nickel and BT layer at 650∼800°C was 90∼100 nm. The capacitor annealed at 650°C showed a dielectric constant of 258 and a dissipation factor of 3.1% at 1 kHz. The leakage current of Ni/BT/Ni capacitors increased with the increase of the annealing temperature. The leakage current density of the capacitors annealed at 650 and 700°C was about 4.5 × 10^-6 and 7 × 10^-4 A/cm² at 100 kV/cm, respectively. The Ni/BT/Ni capacitor prepared by the deposition method offers an attractive alternative for application in MLCCs with high volumetric efficiency.