Atomic hydrogen cleaning has been developed to reduce the amount of surface oxide on Ru-capped Mo/Si multilayer mirrors for EUVL. Atomic hydrogen generated by a heated W wire catalyzer was supplied to a Ru cap layer that had been lightly oxidized by ECR O2 plasma or EUV irradiation. The effectiveness of atomic hydrogen in deoxidizing it was examined by ex situ AES, XPS, and EUV absolute reflectivity measurements; and it was found that the amount of surface oxide was reduced to the initial level and that the EUV reflectivity of a multilayer degraded by oxidation recovered. In addition, the transport of atomic hydrogen thorough a winding quartz tube was demonstrated to be a promising technique. The actual density of hydrogen radicals was directly measured under various conditions so that the conditions for generating atomic hydrogen could be optimized and the required treatment time shortened.
This paper is a summary of the work to date done by the ASET consortia to look at the impact of deposition method on defects. The study includes scratch and bump type defects coated with EUVL quality multi-layers using Magnetron Sputtering, Ion Beam Sputtering, or Ion Beam Sputtering with a secondary ion etch. After the deposition TEM samples were taken of the individual defects and the impact of the deposition method on the multi-layers was examined.