Resist-Free E-beam Lithography for Patterning Nanoscale Thick Films on Flexible Substrates

Abstract

Resist-based lithographic tools, such as electron beam (e-beam) and photolithography, drive today’s state-of-the-art nanoscale fabrication. However, the multistep nature of these processes, expensive resists, and multiple other consumables limit their potential for cost-effective nanotechnology. Here, we report a one-step, resist-free, and scalable methodology for directly structuring thin metallic films on flexible polymeric substrates via e-beam patterning. Controlling e-beam dose results in nanostructures as small as 5 nm in height with a sub-micrometer lateral resolution. We structure nanoscale thick films (100 nm) of Al, TiN, and Au on standard Kapton tape to highlight the universal use of our nanopatterning methodology. Further, we utilize direct e-beam writing to create various high-resolution biomimetic surfaces directly onto ceramic thin films. In addition, we assemble architectured mechanical metamaterials comprising crack “traps”, which confine cracks and prevent overall material/device failure. Such a resist-free lithographic tool can reduce fabrication cost dramatically and may be used for different applications varying from biomimetic and architectured metamaterials to strain-resilient flexible electronics and wearable devices.

Programmable Nanoscale Crack Lithography for Multiscale PMMA Patterns

“…33 Further, nanoscale patterns (mechanical metasurfaces) on metallic and ceramic films are utilized to control, guide, and deflect/trap cracks on demand. 38 However, the crack controllability and uniformity of these methods are poor, and it is difficult to generate high-throughput nanoscale cracks. Thus, existing crack generation methods are still unable to achieve reliable control of nanoscale cracks, and a new method is needed urgently to generate a large-area, stable, and controllable nanoscale cracks.…”

“…For example, using a template prepared by EBL, cracks of tens of nanometers can be obtained through the release of residual stress release and mechanical deformation, which can be used to manufacture nanoscale electrodes. , Resist-free electron-beam irradiation can also be used to selectively suppress cracks in thin films . Further, nanoscale patterns (mechanical metasurfaces) on metallic and ceramic films are utilized to control, guide, and deflect/trap cracks on demand . However, the crack controllability and uniformity of these methods are poor, and it is difficult to generate high-throughput nanoscale cracks.…”