Direct fabrication of micropatterned PDMS nanofilms using maskless UV lithography

Recently, there has been growing interest in ultrathin polydimethylsiloxane (PDMS) films, which are expected to serve as superior coating materials, offering enhanced surface adhesion and improved thermal conductivity to the surroundings. However, fabricating and patterning PDMS nanofilms using conventional techniques remain particularly challenging. In this study, we demonstrate a method for fabricating micropatterned ultrathin PDMS films less than 100 nm thick on substrates using maskless ultraviolet (UV) lithography. Photocurable PDMS is spin-coated to a thickness of several micrometers and then exposed to UV light with a shallow focal depth. After development with xylene, only the photo-cured PDMS remains on the substrate as an ultrathin film with a thickness ranging from several nanometers to a few hundred nanometers, which can be controlled by adjusting the exposure dose. This technique requires no lift-off or etching processes and offers broad applicability for various PDMS-based devices and systems.