Amorphous zirconia (ZrO2) and zirconia-silica (ZrO2-SiO2) thin films were prepared on glass and silicon substrates by radiofrequency (r.f.) magnetron-sputtering by using a zirconia and a 50150 zirconia-silica target, respectively. These films were studied by choosing different substrate temperatures and r.f. powers. ZrO2 films with a dielectric constant of similar to15 and a low loss tangent of similar to 0.01 were obtained at higher temperatures. ZrO2-SiO2 films displayed a consistent dielectric constant of similar to 10 and loss tangent of similar to 0.015, regardless of the deposition conditions. Mechanical properties, such as internal stress and adhesion, of the zirconia and zirconia-silica films were evaluated. Optical properties, such as refractive index and optical transmittance, were also measured. (C) 2003 Elsevier Science B.V. All rights reserved.