Gee-Hong Kim

The UV-Nanoimprint Lithography with Multi-head Nanoimprinting Unit for Sub-50nm Half-pitch Patterns

Nanoimprint lithography is a promising technology to produce sub-50nm half-pitch features on silicon chips. The contact-based nano lithography, such as thermal and/or UV nano-imprint, is well-known as the next generation lithography. Especially, the UV nano-imprint lithography technology has advantages of the simple process, low cost, high replication fidelity, and relatively high throughput. To achieve nano-imprinting process, nano-imprinting lithography equipment must have required some multi-functional units which are imprinting head, self-alignment wafer stage, overlay and alignment system for multi-layer process, master with sub-50nm half-pitch patterns, and anti-vibration unit, etc

Nanoimprint lithography with a focused laser beam for the fabrication of nanopatterned microchannel molds

We present a process based on nanoimprint lithography for the fabrication of a microchannel mold having nanopatterns formed at the bottoms of its microchannels. A focused laser beam selectively cures the resist in the micrometer scale during nanoimprint lithography. Nanopatterns within the microchannels may be used to control microfluidic behavior.

Laser-assisted selective lithography of reduced graphene oxide for fabrication of graphene-based out-of-plane tandem microsupercapacitors with large capacitance

We present a laser lithography technique that uses a focused laser beam to fabricate out-of-plane tandem microsupercapacitors (MSCs) from reduced graphene oxide (rGO) with large areal capacitance. By controlling the depth of focus in a laser beam focused by an objective lens during laser lithography on a graphene oxide (GO) film, a rGO/GO/rGO structure is formed in the GO film, and subsequently, two independent interdigitated electrodes (IDEs) were fabricated on the top and bottom surfaces of the GO film. The out-of-plane tandem MSC with a parallel assembly of two rGO-IDEs showed two times larger areal capacitance than an in-plane single MSC with one rGO-IDE in the same MSC device footprint. The laser-assisted selective lithography technique using a focused laser beam developed in this study can be further applied to improve the energy density of MSCs without increasing the electrode area by vertically stacking multiple out-of-plane tandem IDEs.

Double-Pitch Dual Grating Method for Detecting the Axial Offset in Roll System

We propose a dual grating alignment technique for roll-to-roll positioning which allows achieving nanometer scale alignment by using micro-size marks. The high precision alignment system were designed and manufactured. It was confirmed that the optical system was properly adjusted and fully aligned with the dual gratings. The experiment and computer simulation results were presented. Alignment accuracy below 50 nm was achieved.

A new mold structure to replicate patterns over 1 microm in depth for substrate conformal imprint lithography.

This paper shows an improved mold replication process that uses polyurethane acrylate (PUA) and polyethylene terephthalate (PET) for the fabrication of an ultraviolet (UV) imprinting mold used in substrate conformal imprint lithography (SCIL). With the conventional replication process, which uses hard polydimethylsiloxane (h-PDMS) as a pattern layer, it is difficult to detach the mold from a silicon master for metal oxide semiconductor field effect transistor (MOSFET) that has patterns with over 1-micron depth. However, the method proposed in this paper allows us to easily replicate patterns that have more than 1-micron depth. The key idea of this method is to use PET film as a bonding layer to attach the PUA layer to the polydimethylsiloxane (PDMS) cushion layer to overcome the weak the adhesion force between the PUA and PDMS layer. We demonstrate how to make the modified replica mold and present imprinting results obtained using this replica mold in the SCIL process.

A Piezo-driven Fine Manipulation System Based on Flexure Hinges for Manipulating Micro Parts

This paper presents a manipulation system consisting of a coarse/fine XY positioning system and an out-of-plane manipulator. The object of the system is to conduct tine positioning and manipulation of micro parts. The fine stage and the out-of-plane manipulator have compliant mechanisms with flexure hinges, which are driven by stack-type piezoelectric elements. In the fine stage, the compliant mechanism plays the roles of motion guide and displacement amplification. The out-of-plane manipulator contains three piezo-driven compliant mechanisms for large working range and fine resolution. For large displacement, the compliant mechanism is implemented by a two-step displacement amplification mechanism. The compliant mechanisms are manufactured by wire electro-discharge machining for flexure hinges. Experiments demonstrate that the developed system is applicable to a fine positioning and fine manipulation of micro parts.

Nanopatterning and the flexible stamp replication using thermal and roll typed UV-NIL

In case of UV-Nanoimprint Lithography, a transparent quartz stamp with nano-scale patterns has the problems that are difficult to fabricate, handle and keep. Also, its very expensive to fabricate nano-scale quartz stamp. Furthermore, according to enlarge the substrate size, these problems will be got out of control. In this paper, flexible and transparent replica stamps are fabricated using the polycarbonate, PDMS and polyurethane acryl films by thermal nano-imprint tools (ANT-6T) in order to get over these problems. To verify these stamps, UV nano-imprint lithography process is executed on the roll typed UV-NIL tools (ANT-6R) which is developed by KIMM.