Micropatterned multilayer dielectric filters with two spectral characteristics

Micropatterned interference filters are developed by dry etching of dielectric multilayer stacks. The application of reactive-ion etching (RIE) techniques combined with the use of an etchstop layer are shown to be quite effective in producing two-stage micropatterns with defined spectral properties. By using a MgF2 underlayer the etching of TiO2 and Si02 layers is stopped exactly. Which provides the possibility to develop large area patterns (>lxl cm2) with feature sizes as small as 10 mu m. The distortion of edge features is shown to be better than 1 mu m. A filter array was developed providing high-reflection and antireflection coatings within a period of 20 mu m.