Fabrication and characterization of 30.4 nm Cr/Al/Cr self-supporting filters

Cr and Al were chosen to design the 30.4 nm self-supporting filter based on relation between mass absorption coefficient and wavelength. NaCl was chosen as parting agent, Al was deposited by thermal evaporation, Cr was deposited by electron-beam evaporation, and finally 30.4 nm Cr/Al/Cr self-supporting filters were prepared. Observed under microscope, the filter topography was clean and uniform without apparent pinholes. The Cr/Al/Cr filters were measured in th National Synchrotron Radiation Laboratory in Hefei, and the transmittances of Cr(5 nm)/Al(500 nm)/Cr (5 nm) filter and Cr(12.5 nm)/Al(500 nm)/Cr(12.5 nm) filter are 7.6% and 4.6% at the wavelength of 30.4 nm, respectively. The measured transmittance curves of the two filters in EUV region are in general accordance with the predictio