Fabrication of functional thin films by combining deep UV nanolithography and solution colloidal nanocrystals processes – DUVNANO

The originality of DUVNANO lies in the use of colloidal nanocrystals solutions as negative tone photoresists for direct writing of functional microstructures by DUV photolithography, without any further process step.

Synthesis and characterization of nanocrystals, colloidal solutions and thin layers.
Manufacture of micro-nanostructures by DUV lithography.

Characterizations of the physical properties of thin films and device fabrication.

In progress

DUVNANO is a multidisciplinary project that intends to respond to the demand of new simple processes toward functional thin film by proposing a novel approach that combines colloidal nanocrystals solution and Deep-UV (DUV: 266 & 193 nm) photolithography processes. DUVNANO is a PRC project gathering 2 partners highly specialized on colloidal chemistry and DUV photolithography processes respectively: Laboratory for Innovative Key Materials and Structure-LINK (CNRS UMI 3629) and Institut de Science des Matériaux de Mulhouse-IS2M (CNRS UMR7361). In agreement with Axis 2 of Challenge 3, DUVNANO will focus on a wide range of materials in order to develop a new process rather than aiming for a particular application. The control of this new process will be validated through the realization of simple components such as field effect transistors (FET) or optical networks that can find applications in domain such as “smart windows” for instance.
The originality of DUVNANO lies in the use of colloidal nanocrystals solutions as negative tone photoresists for direct writing of functional microstructures by DUV photolithography, without any further process step. DUV irradiation has indeed the unique property to allow the crosslinking of nanocrystals (NCs) or nanoparticles (NPs) without any additional thermal treatment. With this process, inorganic micro-nanostructured thin films will be obtained in a single step, at room temperature, by a simple process compatible with flexible substrates. The research in coating material and process suitable for solution route is of great interest for industrial point of view. Indeed, thin films are playing a very important and indispensable role in daily life with a material market value estimated to be around $10 billion by 2018.
The project is organized in 4 main tasks: Task 0 will address the project management and will be led by LINK who will cover all administrative and technical management. Task 1 (led by LINK) will be focused on the synthesis and characterization of colloidal solution and thin films based on monodispersed and size-controlled NCs of typical oxides (ZnO, Fe2O3, HfO2…) or metals clusters ( Mo, Ta, Nb, Cu). The synthesis of colloidal solution could be done in aqueous or organic (ethanol, propanol, cyclohexane…). Chemical solution processes (dip and spin-coating, electrophoretic deposition) will be used to address the formation of thin films with good optical quality. Task 2 (led by IS2M) will deal with the DUV photopatterning. Patterning will be achieved by mask lithography, laser direct writing and interference lithography to cover a wide variety of structures and resolutions. The photopatterning will be adapted to the different categories of materials (semi-conductive oxides, dielectric oxides or metal clusters). Basic devices will be produced as described above. Task 3 (co-led by LINK & IS2M) will deal with the physical characterizations (optical, electrical or magneto-optical and magnetic properties).
In comparison to previous works (Wang et al, Science 2017), DUVNANO propose to develop a simpler and quicker process for preparing thin films without photoresists. Very recently, IS2M demonstrated the possibility of crosslinking NP synthetized by LINK. This gives the proof of concept of our goal in this project that is to obtain, directly after DUV irradiation, patterned fully inorganic and nanocrystalized materials. The methodology has been thought in order to minimize the risks using the complementary skills and know-how of each partner.