Inverted Cylindrical Magnetron Sputtering

The shape of inverted cylindrical magnetrons makes them ideal for coating a variety of optical components having non‐planar geometries such as prisms, gratings and spherical lenses. In addition, combining dual cathode mid frequency unbalanced magnetron sputtering with the cylindrical geometry produces a unique source for ion enhanced deposition on planar substrates located at the ends of the cathode. Using a 330 mm diameter source, thickness uniformity on stationary substrates of ± 0.25 % over a diameter of 160 mm and ± 1.3 % over 200 mm can be achieved. SiO₂ and Ta₂O₅ deposited on Si have indices of refraction at a wavelength 632 nm of 1.47 and 2.13 respectively and dispersion similar to those reported for ion assisted processes. The off‐axis nature of this arrangement makes such sources particularly useful where the acceleration of negative ions produced at the target surface can damage sensitive materials such as OLEDs.