Multilayer Ceramic Capacitors with Thin (Ba,Sr)TiO3 Layers by MOCVD

Barium strontium titanate ((Ba,Sr)TiO3; BST) thin films were prepared on platinum-coated MgO substrates at 650°C by metalorganic chemical vapor deposition (MOCVD). Perovskite single phased BST thin films were obtained. Dielectric constant at 1 kHz–100 mV was 1000. Multilayer ceramic capacitor with twelve BST dielectric layers of 0.26 μm thick was formed on the MgO substrate. Capacitance and dissipation factor (tanδ) at 1 kHz–100 mV were 32 nF and 1.5% respectively. Capacitance per unit volume of 33 μF/mm3 provided 10 to 20 times larger volumetric efficiency than the conventional multilayer ceramic capacitors. Temperature coefficient of capacitance was −4000 ppm/°C. The leakage current at 1 V was 2.3×10-9 A that yielded an acceptable CR product of 12.8 MΩ-μF. MOCVD was proposed as one of the promising manufacturing technologies for multilayer ceramic capacitors of high performance with sub-micron thick dielectric layers.