Robust van der Waals Metal Mask for Residue-Free and All-Solid 2D Material Engineering

The van der Waals (vdW) contact, characterized by its bondless interactions, opens up exciting possibilities in cutting-edge mask technology. It enables incredibly close proximity to samples at the atomic level while facilitating non-destructive engineering. In this study, the concept of a vdW metal mask using the template striped ultra-flat Ag/Au film is introduced. The probe tip-assisted metal film transfer under an optical microscope is employed to showcase all-solid and residue-free engineering on 2D materials. The robust nature of the vdW metal mask allows for various treatments, including gas, liquid, solid, plasma, and light, making it a universal tool for fabricating 2D material-based devices and samples with sub-1 µm resolution, all without the need for lithography technologies. With the superiority in simple sample fabrication, ultra-clean surfaces, and robustness under harsh conditions, the technique is believed to flourish in the 2D material research field.