Ceramics for ultra-thin dielectric layer of multilayer ceramic capacitors

Ultra-fine BaTiO₃ synthesized by hydrolysis method was investigated on its particle and crystal structures to understand the size effects on the dielectric properties. The powder calcined at below 800°C contained the hydroxyl groups and had tetragonality c/a of 1.002. They included many rectangular shaped pores. The growth of the particles took place after dissociation of hydroxyl groups completed at above 800°C. A binary phase model is proposed to explain c/a changes with particle size by contribution of the newly developed region during heat treatment. MLCs were prepared with BaTiO₃ thin layer of 1 μm thick with Ni inner electrodes. High-density and homogeneous dielectric layer was designed by utilizing the ultra-fine powder of 150 nm. The capacitor had stable characteristics under practical voltage and temperature conditions