Multi-photon laser lithography of AR-N 4340 photoresist with a spatial resolution at nanoscale

Multi-photon laser lithography (MPLL) is an economical maskless means for high resolution and intrinsic three-dimensional micro/nanostructures fabrication. Here, we report MPLL of AR-N 4340 photoresist, and a spatial resolution of 40 nm is obtained. The relationships between laser parameters and line morphologies are systematically investigated. In the MPLL process, standing wave interference generated by the reflected light from photoresist/air interface and the incident light could greatly influence the bonding capacity between the fabricated lines and glass substrate. Therefore, lines with width smaller than 150 nm can be easily taken away in the development process. In order to obtain line with higher resolution, two rectangular photoresist plates were fabricated for immobilization of the fabricated lines, and a nanoline with a feature size of 40 nm was achieved between them through carefully adjusting the incident laser power. This work is one of the evidences for high fabricating resolution characteristic of MPLL, and it exhibits the potential for fabricating high resolution semiconductor and electronic micro/nanostructures.