Applications and development of BitClean technology including selective nanoparticle manipulation

The technology to selectively remove nanoparticles from a photomask surface by adhering it to an AFM tip (BitClean) first introduced with the Merlin ® nanomachining mask repair platform has been successfully integrated in numerous mask house production centers across the globe over the last two years. One outstanding request for development from customers has been to develop the capability to not only selectively remove nanoparticles from a target surface, but to also redeposit in another target region. This paper reviews the preliminary work done to develop this capability with particular emphasis on its potential applications in creating realistic nanoparticle inspection sites for KLA systems at critical pattern print locations as well as the accumulation of trace amounts of contaminates for better compositional and print-impact analysis. There is also a feasibility study of new ultra-high aspect ratio (AR > 1.5) NanoBits for future BitClean process applications. The potential for these capabilities to be adapted for new applications will be examined for future work as well as a detailed parametric process analysis with the goal of showing how to make significant improvements in BitClean PRE.