Nanoimprinting of gold has the potential to make significant impact in the fabrication of miniaturized devices including optical devices, photonic crystals and biochemical sensors. The deformation behavior and recrystallization of gold structures has profound impact on the accurate replication of the imprinted pattern. An important step in the nanoimprint lithography (NIL) process is the cooling of the mold and resist assembly to room temperatures. The rate of cooling, commonly termed as quenching determines the final shape of the NIL features. Molecular dynamics simulations were implemented to study the nanoimprinting of gold substrates using a silicon mold. Simulations were conducted at room temperature (298 K), gold recrystallization (473K) and melting point (1000K) temperatures. The effect of different cooling rates (quenching) on the deformation behavior and spring back of gold was investigated. These include 0.01ns, 0.05ns, and 0.2ns time steps of quenching at 1fs per time step. The modified embedded atom method (MEAM) potential was used for the system molecules. Fast cooling at 298 K and 473 K whereas, intermediate cooling at 1000 K resulted in good pattern transfer. High fidelity nanoscale features were achieved with a gradient cooling proportional to the initial heating temperatures. The findings of this research provide insight on the effect of quenching in the material deformation and spring back during direct metal nanoimprinting.
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Recent development of nanoimprint and nanoreplication and applications
Nanoimprinting has been applied in many micro- and nanoscale engineered devices; applications include displays, organic electronics, photovoltaics, optical films, and optoelectronics; and in some cases, direct imprinting of functional polymeric devices. Applications in the photonics area can significantly relieve the stringent requirement needed for nanoelectronics. We provide examples of structural colors and optical meta-surfaces facilitated by nanoimprinting, as well as plasmonic lithography masks that can produce deep-subwavelength structures using ordinary UV light.
Inkjet printing has been widely used in many applications, but still faces challenges in pattern precision and feature variations. Combining Nanoimprint for patterning and inkjet printing for material deposition will take the advantage of what both technologies can offer, and can provide a high precision additive manufacturing process. We will show printed photonic devices, e.g. electro-optic polymer based optical modulators.
To extend nanoimprinting to solid materials other than polymeric films will require innovative and non-conventional approaches. One such process is Metal-assisted chemical (Mac) imprint, which combines MacEtch and nanoiprint and enables direct MacEtch of Si substrate using a hybrid imprinting mold having noble metal mask. However, only low aspect ratio structures have been obtained because of the mass-transport limitation in the previous molds. Recently we effectively solved this problem by a using a specially made mold of Pt-coated anodized aluminum oxide (AAO) membrane, where the holes through the entire thickness drastically enhances the mass-transport. As a result, very high aspect ratio Si nanowires were achieved by MacImprint.
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- Award ID(s):
- 1635636
- NSF-PAR ID:
- 10073059
- Date Published:
- Journal Name:
- The 62th International Conference on Electron, Ion, and Photon Beam Technology and Nanofabrication
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Inkjet printing is rapidly emerging as a means to fabricate low‐cost electronic devices; however, its widespread adoption is hindered by the complexity of the inks and the relatively high processing temperatures, limiting it to only a few metals and substrates. A new approach for inkjet printing is described, based on commercially available, particle‐free inks formulated from inorganic metal salts and their subsequent low‐temperature conversion to metallic structures by a non‐equilibrium, inert gas plasma. This single, general method is demonstrated for a library of metals including gold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), lead (Pb), bismuth (Bi), and tin (Sn). As one figure of merit, the resistivities of the printed metals are measured to be between 2× and 10× of the respective bulk metals. Uniquely, it is found that the printed metal films exhibit a very large surface area because of the plasma‐initiated nucleation and growth process, making this technique attractive for sensing device applications. A Bi‐based trace Pb sensor, an Au‐based amyloid‐β42sensor, and an Au‐based strain gauge are fabricated as representative chemical, biological, and mechanical sensors, and are found to exhibit enhanced sensitivity compared to analogues made with conventional methods.
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Accepted Manuscript1.0
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- The DOI is not currently available.
