J. Taniguchi et al., Preparation of diamond mold using electron beam lithography for application to nanoimprint lithography, JPN J A P 1, 39(12B), 2000, pp. 7070-7074
Diamond molds were fabricated by two types of fabrication processes, both o
f which use a conductive intermediate layer between the diamond surface and
polymethylmethacrylate (PMMA) resist to prevent surface charge-up. Using a
PtPd intermediate layer, electron beam lithography and ion beam etching, a
denting line pattern of 600 nm width and 70 nm depth was fabricated. Using
a carbon intermediate layer, electron beam lithography, PtPd lift-off and
oxygen ion beam etching, a convex line pattern of 600 nm width and 110 nm h
eight was fabricated. These diamond molds were pressed into PMMA on a silic
on substrate that was heated to a temperature of 150 degreesC and kept at a
pressure of 23.5 MPa until the temperature dropped below 90 degreesC, and
then the diamond mold was released from the PMMA. The convex line pattern o
f 600 nn width and 150 nm height was imprinted using a denting diamond mold
. The denting pattern of 1100 nm width and 180 nm height was imprinted usin
g a convex diamond mold. PMMA patterns were transferred well over the impri
nted area, by the diamond molds.