New approaches for reactive sputtering of dielectric materials on large scale substrates

Functional coatings on large area glass substrates require fast and stable deposition of dielectric compounds like SiO2 or Si3N4. The paper describes briefly the main problems occurring during de reactive sputtering of insulators. A new mid frequency powered twin magnetron arrangement is able to deposit these films at high rates and excellent process long term stability. Some results for SiO2, Si3N4, TiO2, Ta2O5, SnO2, and ZnO are presented. The deposition rates obtained by use of the new sputter source exceed those known from conventional de sputtering by a factor between 2 and 6. The processes are stable for continuous operation throughout a complete target life of approx. 300 h. All materials show excellent optical properties and are highly resistant against environmental attacks. In case of TiO2, mid frequency sputtering with the TwinMag(R) system results in the dense rutile structure with a refractive index close to 2.7. (C) 1997 Published by Elsevier Science B.V.