Irradiation of low energy ions damage analysis on multilayers

Impacts of low energy He+ ions on reflectivity and stability of EUV multilayers is investigated in this work. Combination of X-ray reflectivity, grazing incidence EUV reflectivity near Silicon edge, and theoretical ion irradiation damage analysis can explain the degradation of ML performances. It is found that MLs irradiation of 4 keV helium ions degrades reflectivity performances with much more impact on grazing incidence mirrors. The proposed method can also regain changes in optical properties due to the irradiations of low energy ions.