Capacitor, resistor and inductor are passive components that occupy over 50% of board space and accounts for 70% of component counts in electronics. Moving the passives off the surface and into the substrates will free up surface area for mounting of silicon chips or for further size reduction. For capacitor, the capacitance is directly proportional to the dielectric constant of the material and the dielectric-electrode area. To maximize area, surface mounted discrete capacitors are typically multi-layered in stack-up or roll-up configurations. Direct fabrication of stacked or rolled capacitors onto a flat substrate is cumbersome and low in yield. Instead, new fabrication methodologies are needed to increase the area and to increase the dielectric constant of the material. In this study...[ Read more ]

Capacitor, resistor and inductor are passive components that occupy over 50% of board space and accounts for 70% of component counts in electronics. Moving the passives off the surface and into the substrates will free up surface area for mounting of silicon chips or for further size reduction. For capacitor, the capacitance is directly proportional to the dielectric constant of the material and the dielectric-electrode area. To maximize area, surface mounted discrete capacitors are typically multi-layered in stack-up or roll-up configurations. Direct fabrication of stacked or rolled capacitors onto a flat substrate is cumbersome and low in yield. Instead, new fabrication methodologies are needed to increase the area and to increase the dielectric constant of the material. In this study, low temperature processable high dielectric constant ceramic barium titanate thin film was investigated. High dielectric materials used in conventional capacitors are typically ceramic powder or metal-organic precursor films sintered at high temperatures. In this study, sol-gel process route and hydrothermal growth techniques were investigated as methodologies to fabricate barium titanate thin film at temperatures compatible with organic substrates. Chemical formulation and process techniques were developed for direct fabrication of barium titanate thin film on organic substrates. In the sol-gel investigation, a seeding approach was used to increase the dielectric properties of low temperature processed sol-gel barium titanate thin film. Microstructural evolution of the low temperature processed films was characterized. Test capacitors were fabricated for testing and characterization of the electrical performance. Results showed that the addition of seeds altered the energetic and thermo-gravimetric profiles during heat treatment and resulted in higher dielectric constant. The dielectric constant increased from 12 to 28 after addition of seeds after 300°C heat treatment, and a capacitance density of 47nF/cm² was obtained.

In the hydrothermal investigation, of barium titanate was grown on titanium foil using a highly alkaline barium precursor solution. Characterization results revealed that high quality barium titanate crystal were formed rapidly after a short period of immersion growth. The capacitance density reached 1500nF/cm² after four days of treatment. Hydrothermal technique was shown to provide higher dielectric constant ceramic thin film. It is likely to be the candidate for the embedded capacitor applications. Experiments were conducted to construct the hydrothermal treated capacitors on polyimide substrates.