Controllable fabrication of Sub-20nm structures with coupling field tip enhancement effect induced by nanosecond pulsed laser irradiation

The nanofabrication technique using nanosecond pulsed laser irradiated probes still faces challenges in achieving controllable processing of nanostructure morphology and feature size, as well as a lack of comprehensive understanding regarding the underlying mechanisms involved in nanostructuring. This study used AFM probes irradiated with nanosecond pulsed lasers to realize controllable processing of nano-lines and nanopatterned structures on metal surfaces by adjusting the tip-sample distances. The controllable capability of the tip-sample distance in influencing the morphological characteristics and feature sizes of nanostructures has been demonstrated, which can be simultaneously characterized by AFM and SEM. The minimum lateral feature size down to 16.65 nm, while the maximum depth is 16.99 nm. Numerical modeling using FEM reveals the simultaneous presence of physical fields, including optical, electromagnetic, thermal, and mechanical near the tip. The essential nanostructuring mechanism involves depositing surface coupling energy onto materials, which induces local thermal energy and enables the removal of material. Different surface coupling energies can be induced by varying the tip-sample distance, which theoretically demonstrates the controllable processing of nanostructure morphology and feature size in experiments. This study highlights the potential application of regularly arranged carbon nanotubes faced by carbon nanotube device fabrication.