Reflective optical element and EUV lithography appliance

摘要

A reflective optical element and an EUV lithography appliance containing one such element are provided, the appliance displaying a low propensity to contamination. The reflective optical element has a protective layer system includes at least two layers. The optical characteristics of the protective layer system are between those of a spacer and an absorber, or correspond to those of a spacer. The selection of a material with the smallest possible imaginary part and a real part which is as close to 1 as possible in terms of the refractive index leads to a plateau-type reflectivity course according to the thickness of the protective layer system between two thicknesses d1 and d2. The thickness of the protective layer system is selected in such a way that it is less than d2.

主权项

1. A reflective optical element for the extreme ultraviolet and soft X-ray wavelength regions, the reflective optical element comprising a multilayer system and a protective layer system, wherein:
a side of the multilayer system facing the protective layer system terminates in an absorber layer, and a reflectivity of the reflective optical element varies by less than 1% for a built-up contamination layer having a thickness that is 10% larger than a thickness d1 of the protective layer system.