Fabrication of roll mold using electron-beam direct writing and metal lift-off process

Roll-to-roll nanoimprint lithography (RTR-NIL) has received considerable attention as a potential solution for large-area nanopatterning with simultaneous high resolution and throughput. However, progress in RTR-NIL is restricted by the difficulty of fabricating nanoscale roll molds. For example, a seamless roll mold is ideal since seams result in lower product yield. To produce a seamless roll mold with the desired nanopatterns, we previously developed a technique that uses an electron beam (EB) for direct writing onto a rotating cylindrical substrate. However, the EB resist is typically made of soft polymer materials and is not sufficiently tough to withstand RTR-NIL. Thus, after development of the EB resist, a pattern transfer process such as dry etching or metal deposition and lift-off is necessary, but dry etching of the roll substrate is difficult because the substrate must rotate in plasma ambient. Therefore, we used the metal lift-off process to fabricate seamless metal-patterned roll molds, with which we successfully achieved RTR-NIL.

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► We examined a metal liftoff using seamless EB resist pattern on a roll mold.
► The seamless pattern was fabricated by EB lithography with rotating stage.
► The pattern width on an aluminum roll was smaller than that on a copper roll.
► We were able to obtain a chromium pattern of 126 ± 9.0 nm width on the aluminum roll.
► We succeeded in roll to roll nanoimprint using the metal pattern roll mold.