The effect of oxygen on the barium titanate film capacitor

Thin BaTiO3 film (5000 Angstroms) capacitor devices were fabricated by using rf sputtering techniques and applying various levels of oxygen-rich environments (0% to 20%). In this study, the gas compositions were specifically 100% Ar and the variations of oxygen content were 1%, 3%, 5%, 10%, 15% and 20%. The dielectric constant was measured in the range of 13 to 19 for the as-deposited samples. For the samples annealed at 750 degrees C in argon for half an hour, the dielectric constant of BaTiO3 films increased as much as a 2 to 3X. It was also observed that the higher the total pressure, the lower the deposition rate was. The addition of the 5% oxygen apparently decreases the deposition rate. The capacitance of BaTiO3 film capacitors produced to-date have little dependence on frequency from 400 Hz to 100 KHz. These film capacitors also exhibited reasonable low dissipation factor (0.005) before annealing and moderate dissipation factor (0.01) after annealing. The resistivity of these films were in the range of 10(12) to 10(14) ohm-cm. Thermal cycling in the temperature range of 50 to 250 degrees C had little impact on the capacitance and dissipation factor. Measurements of dielectric, thermal, and material properties are presented concerning this study.