Periodic nanostructures imprinted on polymers for electromagnetic applications – N-POEM

The aim of N-POEM proposal is to design, fabricate and characterize emerging periodic nanostructures for three electromagnetic and optical functionalities: microwave regime absorption, filtering and antireflecting. These materials are based on strongly coupled periodic structures composed of sub-micrometric patterns. This project groups expertise of different partners in nanofabrication, nanosciences including design and simulation. Nanofabrication processes will be based on nanoimprint on flexible polymer film. These processes will lead to the fabrication of arrays of nanostructures. Their interest is a reduction of technological steps, resulting in a decrease of production cost and time. The aim of this project is to develop technological processes for industrial applications. It will lead to a high maturity level of nanoimprint technique, compatible with industrial requirements in new domains such as devices for aircraft manufacturing, photovoltaic’s, information and communication technologies… The functionalities which will be addressed are : absorption in the microwave regime, filtering in the infrared range, and anti-reflexion in the [500nm-5µm] spectral domain. These three functionalities are representative of three kinds of demonstrators which will be realized during the project.
Demonstrators corresponding to microwave absorption and infrared filtering will be obtained by a coating of adequate material on nanopatterned polymer film. Industrial applications require large surface and light-weighted devices, especially for aircraft manufacturing. Thus, the substrates have to be flexible, thin and larger than 10x10 cm². Moreover fabrication processes have to be robust and low cost. This proposal highlights emerging large-scale lithography which combines high resolution and large surface with the nanoimprint technique.
It is also cheaper than standard lithographies used in microelectronics. Nanoimprint lithography allows easy patterning of organic substrates. The challenge consists here in using flexible substrates. It is the sole solution to produce nanostructured large surface coating. In order to limit the number of technological steps and to reduce the fabrication cost, specific patterns (shape, aspect ratio ...) and processes (highly directional deposition technique) will be developed.
Demonstrators for antireflexion applications will be fabricated on Silicon substrates using a new duplication process based on nanoimprint. Indeed the structures are very complex and are therefore very difficult to achieve directly by standard lithography and etching processes. They will be realized once on silicon and will constitute a mold which will be duplicated on polymer film. This film will be used to reproduce the structures into silicon with a specific process.
Electromagnetic or optical functionalities will be fully characterized with respects to the corresponding wavelength range and compared to numerical models. Also, manufacturing issues will be investigated for mass production and concerns for reliability will be anticipated.