Tantalum oxide thin-film capacitor suitable for being incorporated into an integrated circuit package

The authors have developed a tantalum oxide thin-film capacitor that is compatible with die-bonding by gold-silicon solder and hermetic glass-sealed packaging. Its lower electrode is a metal plate, and the upper one is a metal thin film. A Ta₂O₅ thin-film capacitor that uses a rolled tape of iron-42% nickel alloy as the metal plate and aluminium as the metal thin film is described. This capacitor can withstand a temperature of 500°C for more than ten minutes. Its thermal coefficient of capacitance is less than 400 p.p.m./°C in the range from 25°C to 150°C. The dependence of capacitance on frequency is very small in the range from 1 MHz to 1 GHz. The dielectric loss tangent is less than 0.5% at 1 MHz. The authors compared with Ta ₂O₅ thin-film capacitor´s performance with that of a barium-titanate-based single-layer chip capacitor by measuring the gain of an amplifier composed of an amplifier IC chip and a capacitor in a leadless chip carrier package. Incorporating Ta₂O₅ thin-film capacitors into the IC package was confirmed to be a more effective decoupling technique, particularly above than 100 Mhz