Periodic Reporting for period 4 - NanoGraphy (Plasmon Enhanced Photocatalytic Nano Lithography)
Berichtszeitraum: 2024-07-01 bis 2026-06-30
The emergence of nanoscience and nanotechnology, with envisioned applications spanning from nano-optics and nanophotonics to plasmonics and nano-electronics, depends on the capability to fabricate a variety of nanometre-scale structures. Despite the impressive development in these fields, breakthroughs remain in the laboratory, largely due to technological limitations in the ability to manufacture complex and accurate nanometer-resolved surface patterns, with satisfying resolution and on a large area. The development of a new fabrication methodology is thus required. We are developing a novel technique for nanoscale photolithography that would bring 21st-century nanotechnology breakthroughs out of the lab and into the public sphere. The inspiration for this technique originates in our discovery that multi-electron photocatalytic reactions could be directed to progress exclusively under a plasmonic field. In the course of this project, we leverage this phenomenon for pattering and high-resolution nanolithography. We employ plasmon-enhanced optical phenomena for promoting a specific set of photocatalytic reactions in a controlled and highly confined manner in order to enable nanoscale patterning.
The project required a transition from three-dimensionally confined colloidal nanoparticles suspended in solution, on which the initial proof-of-concept was demonstrated, to thin films (Stage 1). We successfully completed this transition and moved to fabricating nanostructures via electron beam lithography on silicon substrates. This was followed by fundamental investigations into the underlying physical phenomena (stage 2). The original project proposal outlined two parallel research paths: a) the construction of a prototype demonstrating dynamic writing capabilities, and b) the development of a photocatalytic mask enabling true CMOS-compatible nano-photolithography. Due to recruitment limitations during the COVID-19 pandemic and a delayed research start, we chose to focus exclusively on the latter path, which represents the project's ultimate objective. We successfully fabricated first- and second-generation antennas in a variety of designs, guided by simulations of field enhancement. We investigated different catalytic reactions and operating conditions to better understand their impact on reaction pathways and to elucidate the underlying mechanism — an essential step for effective mask design and optimization. In parallel, we initiated the development of robust, high-throughput characterization tools. Despite the project’s premature termination due to personal considerations of the principal investigator, we achieved a major milestone: demonstrating the technique’s ability to pattern ordered arrays of resist dots on a silicon wafer, using visible light in ambient air.
The resulting features had a height of 10 nm and a diameter of just 4 nm. This breakthrough exceeds even the most optimistic performance projections for EUV lithography anticipated by 2040. With further development, we are confident that this technology will set a new benchmark for semiconductor manufacturing — offering a more accessible, scalable, and efficient alternative to current methods, with the potential to fundamentally change the way in which nanotechnology affects modern life.