Manufacturing technologies for miniaturized interference filters

Miniaturized interference filters were designed and fabricated using two different manufacturing technologies. Applying micromachined ceramic masks during the coating processes interference filters with 1 mm lateral feature size and an alignment accuracy of 50 mu m were arranged in an array consisting of three different filters. The filter edge definition obtained by this method was smaller than 50 mu m. By applying ion assisted deposition (IAD), a low-temperature coating process, the spectral sensitivity of receiver cells has been modified by coating the cells directly. A combination of coating processes, microlithographic masking procedures, and dry etching technologies made it possible to arrange three different stripe filters with minimum filter features of about 5 mu m side by side. The accuracy during mask alignment and the filter edge definition was also within 1 and 2 mu m, respectively.