You are here

Nanolithography, the power of technology to manufacture nanostructures

Nanoimprint lithography (NIL), or simply imprint lithography, is one of the pioneering techniques in nanotechnology, used to fabricate nanometer-scale structures. One of the leading experts in this discipline is Dr. Nikolaos Kechagias. He directs the Nanoimprint Lithography platform of the Catalan Institute of Nanoscience and Nanotechnology (ICN2). Biocores spoke with this specialist to learn more about the possibilities offered by this innovative technology.

“Nanoimprint lithography (NIL) is an alternative nano-patterning technique which uses a mold (containing micro and/or nano metric scale features) to imprint in a polymer layer,” says Dr. Kechagias. This nanofabrication process, which takes a few minutes or even seconds, “relies on the mechanical deformation of a thin polymer film when heating it above its glass transition temperature while progressively applying pressure.” In addition to the conventional process, the ICN2 researcher has described a modified version, called ultraviolet light assisted NIL (UVNIL), which uses a monomer film sensitive to ultraviolet light to replicate the mold’s geometries.

 nanolithography

Credit: image provided by ICN2 Nanoimprint Lithography Platform.

This fabrication method, compatible with the development of integrated semiconductor circuits, or nanoelectromechanical systems, is a high-throughput, low-cost technique to fabricate high resolution nanoscale patterns. According to Dr. Kechagias, “NIL technology has been extensively studied to fabricate polarizers, anti-reflective structures, resonant grating filters, plasmonic devices and integrated photonic circuits.” The expert also remarked that this method has sufficient potential to fabricate products “such as lasers, light emitting diodes, organic light-emitting diodes, batteries, CPU’s and memory devices, micro/nano-fluidic products, data storage, fuel cells and solar cells, optics (gratings, SERS, anti-reflective structures and integrated optical devices) and others related with life sciences.”

This fabrication method, compatible with the development of integrated semiconductor circuits, or nanoelectromechanical systems, is a high-throughput, low-cost technique to fabricate high resolution nanoscale patterns. According to Dr. Kechagias, “NIL technology has been extensively studied to fabricate polarizers, anti-reflective structures, resonant grating filters, plasmonic devices and integrated photonic circuits.” The expert also remarked that this method has sufficient potential to fabricate products “such as lasers, light emitting diodes, organic light-emitting diodes, batteries, CPU’s and memory devices, micro/nano-fluidic products, data storage, fuel cells and solar cells, optics (gratings, SERS, anti-reflective structures and integrated optical devices) and others related with life sciences.” 

The ICN2 has an in-house nanoimprint lithography platform. Dr. Nikolaos Kehagias, head of the unit, told Biocores that this platform “offers tailored functional surfaces by introducing micro and/or nanoscale features on the relief of the targeted surface.” The replication technologies that they have are not for exclusive use in academic research, but are “industry-compatible and have been demonstrated to work on a large number of materials. We focus on developing nanostructured (down to 50 nm) plastic surfaces realized by injection molding and roll-to-roll nanoimprint lithography methods,” says Dr. Kechagias.

nanolithography2

Credit: image provided by ICN2 Nanoimprint Lithography Platform.

The possibilities of this nanofabrication platform are not limited to life sciences, although these have been among the most recognized applications. As Dr. Kechagias remarked to Biocores, “for example, hierarchical micro/nano structures have a significant impact to the surface wetting properties in comparison to their planar ones. We have observed a 70% increase in the water contact angle when our particular hierarchical structures are present on the same polymer surface. This effect opens a path to self-cleaning surfaces or surfaces which have anti-bacterial properties”. Other possibilities offered by nanoimprint lithography are based on controlling structural dimensions or properties of materials. “For example, we can generate decorative color without using any pigments or chemicals, surfaces which control the light (for example, concentrating lenses to focus the sunlight on photovoltaic panels) and much more,” says Dr. Kechagias.

The ICN2 group is one of Europe’s most experienced in nanolithography, a technique in which the continent is worldwide leader. “It could be said that our platform constitutes one of the most well-equipped teams in Europe, where no more than four other groups have facilities like ours,” says the researcher. The potential economic impact of nanofabrication is highly relevant, as in the opinion of Dr. Kechagias, “NIL technology exhibits a most promising outlook, projected to reach US$ 13.9 billion by 2020.” Its potential is also driven by its main advantages: the feasibility of the process, its overall cost of ownership, the ability to create micro and nano scale patterning at the same time and its high throughput and low cost. “In addition to the fact that NIL is a mechanical process, it does not use any beams (electron, photons etc.) to perform the lithography. Therefore we do not alter the physical and chemical properties of the imprinted polymer. Consequently NIL can be implemented in any functionalized polymer matrix without changing its properties,” says Dr. Kechagias, head of a group responsible for a number of research and transfer projects based on this nanofabrication platform.