Raster-Atomic force nanolithography: New insights towards the fabrication of 3D nanostructures on PMMA and Silicon Nitride

The rapid advancement of nanoscience has driven significant interest in manipulating materials at the nanoscale, a capability critical to diverse High-tech fields. Achievements in nanoscale analysis and nanofabrication have facilitated practical applications across a range of fields, including nanoelectronics, nanofluidics, drug delivery, optical and plasmonic devices, and biosensing. Nonetheless, conventional top-down fabrication techniques, such as electron beam lithography, focused ion beam lithography, soft lithography, and nanoimprint lithography, are frequently constrained by factors such as cost, scalability, and manufacturing complexity. Scanning Probe-based Lithography (SPL) has recently emerged as a promising alternative, offering precise nanostructure fabrication and immediate characterization in ambient conditions. This paper focuses on Raster-Atomic Force nanolithography (R-AFL), highlighting its capability for fabricating 3D nanostructures on Polymethyl methacrylate (PMMA) with minimal process steps. By coupling this technique with a simple wet etching process using Methyl Isobutyl Ketone (MIBK) and 2-propanol (IPA), enhanced resolution and quality of the nanostructure are achieved. Furthermore, the nanostructures are successfully transferred to a Silicon Nitride (Si_xN_y) substrate via plasma etching, demonstrating the versatility of the approach. This combination of AFM-based lithography, wet etching, and plasma transfer represents an innovative and efficient method for creating nanopatterned surfaces on both soft and hard substrates, addressing key limitations of conventional nanofabrication techniques.