Laser Nano-Patterning For Large Area Nanostructure Fabrication

The laser nano-patterning technique described here makes use of laser irradiation through a transparent microlens array to generate nano-patterns over a large area in a short time. A femtosecond laser and an excimer laser were used to pattern phase change and photoresist thin films. Due to the ultra-short pulse duration of the femtosecond laser (800 nm/100 fs) and multi-photon absorption effect, nano-patterns down to about 50 nm in feature size were created in the phase change films by laser irradiation at an optimized laser power. By using a 248 nm/23 ns KrF excimer laser, feature sizes of approximately 80 nm can be obtained on a photoresist surface, which implies a high resolution of one third of the laser wavelength. Such small feature size shows that it is possible for the laser nano-patterning technique to overcome the optical diffraction limit for large area surface nano-structuring.