A practical magnetron sputtering system for the deposition of optical multilayer coatings

A laboratory magnetron sputtering system with a wide-band optical monitor is described whose cryo-pump and gas handling system are automatically controlled. At any one time, up to four different 45 cm × 15 cm planar magnetron targets can be mounted in the deposition chamber. These can be attached to either dc or rf power supplies for direct or reactive deposition of metal, oxide or nitride films. Typical target materials include Al, Zr, Si, Nb, Mo, C and W. Good uniformity can be attained on stationary, oscillating or rotating substrates. The optical constants of several materials will be given for different deposition conditions. The materials and thicknesses of individual layers making up an optical multilayer system are entered into a computer which controls the substrate motion and the deposition time. After a relatively simple calibration process, this equipment is capable of producing, for example, coatings consisting of between 20 and 30 layers with an accuracy of 1 or 2%. The wide-band optical monitor is available for checking the performance of the system during its deposition. Several examples will be given of multilayer coatings prepared in this way.