Electroforming of Ni mold for imprint lithography using high-aspect-ratio PMMA microstructures fabricated by proton beam writing

Proton beam writing (PBW) was applied for micromachining of a PMMA mother for Ni electroforming. Proton beam focused down to about 1 μm at beam energy of 1.0-3.0 MeV was used for PBW on a PMMA layer on Si or Cu substrate. Using modified techniques for developing of 15-30-μm thick resists exposed to PB and electroforming steps, fabrication of the Ni structures with aspect ratio up to 30 by electroforming with a 30-μm thick PMMA mother micromachined by PBW was successful. We also tried thermal imprint using a 15-μm thick Ni microstructure on Cu substrate with an aspect ratio of more than 4 on a PMMA film.