Abstract
We fabricated microlenses and the logo of the National Institute of Advanced Industrial Science and Technology (AIST) on Pyrex glass by employing thermal nanoimprint technology. The mold material used for imprinting on Pyrex glass was an amorphous Ni–P alloy that was deposited on Inconel-600 by electroless plating technology. The complete fabrication technique consisted of highly accurate processing by focused-ion-beam (FIB) on material that involved a high-temperature thermal treatment that has the advantage of improving the hardness of the mold. An amorphous Ni–P alloy layer on an Inconel-600 substrate was characterized by measuring its X-ray diffraction spectrum. Using this technique we successfully developed a low-cost mold for imprinting on Pyrex glass instead of using a more expensive glass-like carbon mold that is commonly used for this purpose. Microlenses with concave curvatures having radii of 12 and 20 µm were created on the mold by a FIB system equipped with three-dimensional computer-aided-design (CAD) software. This mold was used for thermal imprinting on Pyrex glass substrates to fabricate microlenses and the AIST logo. When polished Inconel-600 was used as a substrate for molds, the accuracy of the Ni–P mold proved to be of higher quality than a mold made of unpolished Inconel-600. The microlenses made using Ni–P/polished-Inconel-600 molds showed lubricious surfaces that were not possible to achieve using Ni–P/unpolished-Inconel-600 molds. Moreover, some of the parameters in Ni–P electroless plating were changed in order to make three kinds of molds with P content ratios of 4, 8, and 16 wt %. The micro-vickers hardness caused by thermal treatment and the differences among the transcript values on Pyrex glass were also evaluated experimentally.