Electron beam direct writing of nanodot patterns on roll mold surfaces by electron beam on–off chopping control

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Roll-to-roll (RTR) technology is a high-throughput production method for nanoimprint lithography (NIL). However, the fabrication of a roll mold for RTR-NIL is difficult because of the cylindrical shape of the mold. We previously developed a technique for direct writing with an electron beam (EB) on a rotating cylindrical substrate that permits the production of seamless molds. However, the only patterns that could be written by this technique consisted of lines and spaces. Because nanodot patterns would be very useful for producing novel devices, we developed a direct EB method for writing patterns of nanodots onto the surface of a rotating roll mold by EB on–off chopping control by a beam-blanking system. However, because the EB resist is a soft polymer material, it has insufficient toughness for use in RTR-NIL. Therefore, after the development of the EB resist on the roll mold surface, a pattern-transfer process, such as dry etching or metal deposition and lift-off, is necessary. We chose the metal lift-off process, and we developed a technique for vacuum evaporation with a rotating cylindrical substrate, which we used to produce metal roll molds with various nanodot patterns.