| 摘要 |
PURPOSE:To prevent deterioration of a photoresist mask by forming an aqua- regia-resistant coat on a precious metal foil for producing a circuit pattern before etching the same. CONSTITUTION:A thin film of titanium nitride 3 is formed on the surface of a substrate by the DC magnetron sputtering so that a precious metal foil on the substrate surface is coated therewith. The thin film is an aqua-regia-resistant thin film formed for example of a metal such as titanium, niobium or tantalum, or titanium nitride, or an aqua-regia-resistant metal oxide such as silicon oxide or titanium oxide. The thin film is then covered with a photoresist mask 4, and exposure-and-development is performed to form openings 5 in the mask 4. The parts of the titanium nitride thin film 3 exposed in the openings 5 are etched with an etching solution principally composed of ammonium hydrogen fluoride so that further openings 6 are opened to expose the noble metal foil 2. The part of the noble metal foil exposed in the opening 6 are etched off with an etching solution of aqua regia type having increased concentration of hydrochloric acid. Thereby, an electric circuit is produced under the titanium nitride thin film 3. |
