Characteristics of RF sputtered barium titanate thin films

Results of a study on the deposition of thin-film barium titanate (BaTiO3) by RF sputtering are discussed. BaTiO3was deposited onto Pt foil and onto thin-film electrodes on various substrates, and counterelectroded to form metal-dielectrio-metal structures. Dielectrics were deposited at substrate temperatures from 23° to 1000°C, some of the dielectrics fired in air at temperatures up to 1400°C after deposition. On bulk Pt, the BaTiO3film matrix indicated an average grain size of 2000 Å after heat treatment Constant Ba/Ti ratios were measured for the films deposited over the entire substrate temperature range. Dielectric constants ranged from 16- 1900, the tan δ of the capacitors varying from 0.005 for amorphous films to 0.065 for polycrystalline films with highest dielectric constants. Effects of temperature and frequency on the capacitors and the charge-voltage and field dependence of the dielectric constant are described. Current-voltage relationships, breakdown strengths, and processing conditions indicate the potential of the capacitor structures for practical applications.