Optical elements for EUV lithography and X-ray optics

In contrast to vacuum ultraviolet (VUV) and deep ultraviolet (DUV) light used for current lithography technologies, extreme UV (EUV) light with a wavelength of 13.5 nm is strongly absorbed by any material. Optical coatings for infrared (IR), visible, and UV light are predominantly fabricated by thermal or electron beam evaporation. The fabrication of such demanding nanometer multilayers needed, for instance, for EUV lithography is only possible if accurate metrology tools are routinely available which enable the immediate inspection of the layer properties. One of the most powerful techniques for the characterization of EUV and X-ray reflection coatings is reflectometry. The steady power increase of EUV sources results not only in higher EUV intensities but also in stronger heating of the optical components. One promising approach for hard X-ray focusing which has arisen in recent years is the concept of multilayer Laue lenses (MLLs).