Electrostatic force-assisted nanoimprint lithography (EFAN)

We present and demonstrate a novel imprint method, electrostatic force-assisted nanoimprint lithography (EFAN), where a voltage applied between a mold and a substrate generates an electrostatic force that presses the mold into a resist on the substrate. We have successfully used EFAN to pattern nanostructures in a photocurable resist spin-coated on a wafer, with high fidelity and excellent uniformity over the entire substrate, in ambient atmosphere without using a vacuum chamber. In initial tests without any process optimization, 100 nm half-pitch gratings with a residual layer thickness of 22+/-5 nm were imprinted across a 100 mm diameter wafer in about 2 s. Furthermore, numerical calculations show that the field magnitude experienced by the dielectric layers on the substrate is much less than their breakdown limit. Hence, EFAN is well suited for step-and-repeat nanoimprint lithography, and its simple operation can simplify and speed up multilayer alignment process.