High performance multilayer coatings

#The present invention relates generally to the art of sputtering metal-containing films on non-metallic substrates, and more particularly to the art of magnetic sputtering of multiple-layer metal-dielectric transparent films on glass.

#U.S. Pat. No. 3,990,784 to Gelber discloses a coated architectural glass system comprising a transparent substrate and a multi-layer coating comprising first and second metal layers with a dielectric layer between them, wherein the first and second metal layers have a thickness ratio so that the transmission of the coating can be changed independent of its reflection properties by varying the thickness of the metal layers while maintaining the ratio constant. The dielectric has a thickness such that the reflection from the coating is not strongly colored.

#U.S. Pat. No. 4,022,947 to Grubb et al discloses a transparent panel capable of transmitting a desired portion of visible radiation while reflecting a large portion of incident solar radiation and a method of preparing same, by sputtering an iron, nickel and chromium alloy to obtain a transparent metal film, and reactively sputtering the same or a similar alloy in the presence of oxygen to form an oxide film. In one preferred embodiment, the metal film lies between the substrate and the metal oxide film. In another preferred embodiment, the metal oxide film lies between the substrate and the metal film.

#FIG. 1 illustrates the percent transmittance at 550 nanometers (nm) of a titanium oxynitride film on glass as a function of film thickness, measured in number of cathode passes, at various percentages of oxygen in nitrogen.

#FIG. 2 illustrates the deposition rate, in Angstroms per cathode pass, of a titanium oxynitride film as a function of oxygen concentration in the atmosphere of the coating chamber.

#FIG. 3 illustrates the absorption of a quarter wavelength (about 600 Angtroms thick) titanium oxynitride film as a function of the oxygen concentration in the atmosphere of the coating chamber.

#In a conventional magnetron sputtering process, a substrate is placed within a coating chamber in facing relation with a cathode having a target surface of the material to be sputtered. Preferred substrates in accordance with the present invention include glass, ceramics and plastics which are not detrimentally affected by the operating conditions of the coating process.

#The cathode may be of any conventional design, preferably an elongated rectangular design, connected with a source of electrical potential, and preferably employed in combination with a magnetic field to enhance the sputtering process. At least one cathode target surface comprises titanium which is sputtered in a reactive atmosphere to form a titanium oxynitride film. The anode is preferably a symmetrically designed and positioned assembly as taught in U.S. Pat. No. 4,478,702 by Gillery et al, the disclosure of which is incorporated herein by reference.

#The titanium oxynitride of the present invention is deposited by sputtering a titanium cathode in an atmosphere comprising oxygen and nitrogen. The composition of the atmosphere preferably ranges from 10 to 50 percent oxygen and from 90 to 50 percent nitrogen. An atmosphere comprising 10 to 25 percent oxygen and the balance nitrogen is particularly preferred.