Reticle blanks for extreme ultraviolet lithography: ion beam sputter deposition of low defect density Mo/Si multilayers

We report on the growth of low defect density Mo/Si multilayer (ML) coatings. The coatings were grown in a deposition system specifically designed for EUVL reticle blank fabrication. Complete, 81 layer, high reflectance Mo/Si ML coatings were deposited on 150 mm diameter (100) oriented Si wafer substrates using ion beam sputter deposition (IBSD).

Added defects, measured by optical scattering correspond to defect densities of 2x10-2/cm2. This represents a reduction in defect density of Mo/Si ML coatings by a factor of 105.