Fabrication of metrology test structures with helium ion beam direct write

The availability of metrology solutions, one of the key factors to drive leading edge semiconductor devices and processes, can be confronted with difficulties in the advanced nodes. For developing new metrology solutions, high quality test structures fabricated at specific sizes are needed. Conventional resist-based lithography has been utilized to manufacture such samples. However, it can encounter significant resolution difficulties and require complicated process optimization. In this work, potential of helium ion beam direct milling (HIBDM) for fabricating metrology test structures with programmed imperfection is investigated. Features down to 5 nm are resolvable without needing any resolution enhancement technique. Preliminary results demonstrate that HIBDM can be a promising alternative for fabricating metrology test structures to develop advanced metrology solutions in sub 10 nm nodes.