Bilayer reversal imprint lithography: direct metal–polymer transfer

Abstract

A method of transferring a bilayer of polymer capped with metal to a substrate is developed with a mould that is coated with a metal followed by a polymer. A self-assembled monolayer chemisorbed on the mould surface plays a key role in the bilayer transfer. This bilayer reversal imprint lithography offers a distinct advantage over other imprint techniques in allowing for a high aspect ratio of the pattern transferred onto a substrate, which has been difficult to obtain for small feature sizes. The method requires only one etching step as opposed to the two etching steps typically needed in the imprint lithography, which can degrade the pattern fidelity.

Hot embossing by Joule heating

“…It is found that with such a Joule heating hot embossing process, microstructures can be replicated from mold to substrate successfully in a cycle time of about 5 min. As the similar results as other reversal imprinting investigations, 9,10 it is also found that the mold with antistick coating could be used without loss in the pattern quality. From line profile of Fig.…”

Transfer Printing Techniques for Materials Assembly and Micro/Nanodevice Fabrication

“…Two‐layer printed structures are possible (e.g., by printing a flat metal film on the surface of a patterned metal film in which some areas of the polymer adhesive are exposed),189, 190 for use as vertical interconnects in devices on plastic substrates 191. The method can also be used to invert a stacked integrated structure, as demonstrated in the printing of metal/polymer bi‐layers on polymeric substrates 192. Plasticizing solvent vapor can decrease the glass transition temperature, to further facilitate printing in this mode 193…”

“…Upon contact with a receiving substrate, followed by mild heating the patterned PVAc film detaches upon removal of the PUA stamp. Printing is once again driven by differential adhesion strength at the aluminum/PVAc and PVAc/substrate interfaces 50, 192. A double roller setup can press the inked PUA/PET stamp into contact with a moving, large area receiver substrate 50…”

Nanoimprint Lithography

“…This bilayer reversal imprint lithography offers a distinct advantage over other imprint techniques in allowing for a high aspect ratio of the pattern transferred onto a substrate, which has been difficult to obtain for small feature sizes. The method requires only one etching step as opposed to the two etching steps typically needed in the imprint lithography, which can degrade the pattern fidelity (Suh et al, 2004). Li et al, studied the pattern transfer fidelity of NIL by patterning sub-micron MESFET gates on six-inch wafers.…”