Next generation lithography is likely to deploy extreme UV (EUV) light at 13.5 nm wavelength for key manufacturing processes. Currently, all promising EUV light source concepts require efficient light collection optics in order to deliver sufficeintly high light power for profitable chip production. With densely nested Wolter-Type 1 reflective optics we designed, and fabricated such optics. In this paper we report on the latest achievements in design, development and on our first at wavelength testing results of such collection optics.
EUV sources are designed to emit radiation around 13.5 nm wavelength into a solid angle of up to 2π sr. With a suitable Wolter type 1 grazing incidence optic such EUV photons can be collected with high efficiency and focussed onto a preferred target. Such Wolter type 1 collectors are characterized by densely nested concentric and confocal mirror shells with fixed distance from the source and the intermediate image.
In this paper we will report on optical and mechanical design, development, fabrication and testing of nested Wolter type 1 collectors, capable of collecting and imaging EUV photons at 13.5 nm wavelength with high efficiency.