Fabrication of Mo/Al multilayer films for a wavelength of 18.5 nm

This paper reports the fabrication and evaluation of Mo/Al and Mo/Si multilayer films (MLs) for a wavelength of 18.5 nm. Calculated reflectivities of Mo/Al MLs at an incident angle of 10 degrees were about 7% higher than those of Mo/Si MLs. MLs were fabricated using an RF-magnetron sputtering deposition system. The measured reflectivity of Mo/Al MLs was 33.5%. The cause of the decreasing reflectivity was supposed to be the surface and interfacial roughness. In the surface observation utilizing atomic force microscopy, the surface roughness of Mo/Al MLs was dominated by the Al layer. Therefore, the conditions for fabricating Al films were optimized.