Nanofabrication mechanism of λ/20 features achieved by coupling field tip enhancement induced with nanosecond laser irradiating AFM probe tip

The nanofabrication mechanism of coupling field tip enhancement induced by laser-irradiated probe tip was investigated theoretically and experimentally. The coupling mechanisms and distribution characteristics of the enhanced electric, thermal, and stress fields were studied at wavelengths of 400–800 nm and tip-sample distances of 1–20 nm for 9 material combinations. The simulation results demonstrated that the electro-thermal coupling effect and thermal–mechanical coupling effect are the basic principles of this technique, independent of the materials. It was also demonstrated that probe damage due to mechanical scratching can be avoided through the estimation of probe displacement. The superposition of electromagnetic energy and thermal energy generates an extremely constrained total energy of up to 10–12 orders of magnitude near the tip end. The nano-line structures were processed at each tip-sample distance, and nanostructures with a feature size of approximately λ/20 were obtained. The experimental results and the total energy distribution demonstrated that the interaction of the coupling field tip enhancement with samples is in the form of total energy deposits on materials. The significance of this study will not only enable a refined understanding of the fundamental physics of surface nanostructuring but will also advance the scientific and industrial applications of the technology.