Patterning of multilayer dielectric optical filters using metal masks fabricated by electroforming and photolithography

Ni films, replacing photoresists, serve as masks in the selective deposition of optical thin films by electron-beam gun evaporation at a substrate temperature of 300°C. Photolithography is adopted herein to define the growth of Ni films by electroforming. Mosaic patterns with a width of 20 μm are employed as red color filters, which are longwave pass. These red filters are formed from alternate SiO₂ and TiO₂ layers and have a mean transmittance of (90%. The experimental results show that the combined use of photolithography, electroforming, and electron-beam gun evaporation can deposit miniaturized multilayer dielectric coatings with high light transmittance in a hot process.