Freestanding Photoresist Film: A Versatile Template for Three‐Dimensional Micro‐ and Nanofabrication. (19th August 2020) - Liu, Yuyang
Abstract: Ultrathin freestanding films with well‐defined micro/nanostructures and robust mechanical properties are applied in many engineering applications including microelectronics, optics, filtration and separation, biomedical engineering, and nanotechnology. Although considerable efforts have been made toward the fabrication of freestanding thin films, it is still a significant challenge to develop a simple and reliable process for producing freestanding films with ultrathin thickness, well‐regulated micro/nanopatterns, robust mechanical properties, macroscopic coverage area, and multi‐layered composite structures. Here, a significant advancement is reported in this regard. This study shows a new sacrificial‐layer‐free (SLF) lifting‐off process, integrated with conventional micro‐ and nanolithography, enabling the release of micro‐ and nanopatterned photoresist (PR) films from the supporting substrate with unprecedented pattern coverage and structure characteristics. The freestanding PR film is resilient, can withstand significant bending and deformation, and is sufficiently flexible to be transferred onto substrates with 3D topography as a conformal soft stencil for further technological processing and applications. Moreover, the SLF lifting‐off process provides a simple approach to prepare single‐layered and multi‐layered freestanding composite films. The results suggest that the novel SLF lifting‐off process can significantly extend the capability of 3D micro‐/nanofabrication. Abstract : A novel sacrificial‐layer‐free lifting‐off process can release a pre‐patterned photoresist film from the supporting substrate, leveraging the formation of bubbles at the interface during the decomposition of hydrogen peroxide solution. The flexible and durable freestanding film with lithographically defined features can serve as a versatile platform such as template, stencil, and scaffold for rapid, scalable, and robust 3D micro‐ and nanofabrication.