Unbalanced Magnetron Sputtering Using Cylindrical Target for Low-Temperature Optical Coating

A new optical coating technology was developed for the first time using unbalanced magnetron sputtering combined with a cylindrical target. A significant reduction of ignition and glow discharge voltages were observed by adding magnets to carry out the unbalanced magnetron sputtering. A high deposition rate of 30 nm/min was realized for TiO 2 film preparation; this rate was approximately 3 times larger than that obtained by conventional magnetron sputtering. Moreover, deposition power efficiency twice as large as that obtained by conventional magnetron sputtering was realized. A fine-grain structure was observed and a large refraction index of 2.65 was obtained.