Roughness development during growth and ion beam polishing of molybdenum silicon mulitlayer films

Room temperature deposition of single and multiple layers of silicon and molybdenum has been explored by scanning tunneling microscopy at growth conditions used for Mo/Si multilayer optics. Periodic Mo/Si multilayer films with a molybdenum layer thickness of 2.5 nm and a silicon layer thickness of 5 nm show an evolution of the surface roughness that is similar to polycrystalline film self-affine growth. By applying ion beam treatment to the silicon layers this increase of the roughness with layer thickness is completely compensated, yielding a final roughness similar to the first ion treated silicon layer. The ion treatment step used here is most efficient in reducing surface roughness with lateral sizes between 5-10 nm