Multiphoton nonlinear lithography based on rare-earth upconversion nanoparticles

Multiphoton lithography has broken through the resolution limitations of traditional lithography techniques by using nonlinear optical effects, and has become one of the core technologies in micro and nano-fabrication, biomedicine, and nanotechnology. However, multiphoton lithography relies on high-power femtosecond pulsed lasers which can cause thermal damage effects, and it will compromise the integrity of lithographic structures and affecting precision. To solve these problems, this study innovatively proposes a lithography method based on multiphoton-like rare-earth upconversion. Under the irradiation of a low-power continuous-wave laser, this method eliminates thermal damage effects and achieves stable large-area micron-scale lithography. We use the energy level transition mechanisms of lanthanide ions, and a nonlinear upconversion process is achieved in the photoresist which leads to its curing. Finally, we get the polymer structures with a feature size of 3 μm at a laser power of 20 mW. This method ensures micron-level lithographic precision and improves the utilization efficiency of photon energy at the same time. It resolves various problems which associate with the high power requirements of traditional multiphoton lithography and offers a new direction for the development of lithography technologies. It shows promising application prospects in semiconductor manufacturing, biomedicine, and nanotechnology.