Electrochemically fabricated ultrafine nickel masks for the fabrication of MoS2-based devices

Transition metal dichalcogenides (TMDs) are considered promising candidates for the next generation of electronic building blocks in integrated circuits due to their superior performance in mitigating various challenges such as short channel effects. Optical lithography and electron beam lithography are commonly employed for fabricating electrical contacts and patterning TMDs to create electronic devices. The atomic layer structure of TMDs is highly susceptible to external conditions, making conventional lithography methods, which often leave undesirable polymer residues and involve high-energy electron radiation, not ideal for achieving high device performance. Shadow mask lithography has been used to define electrodes and etch patterns on these sensitive materials, thereby avoiding the need for photoresists and electron irradiation. In this study, we introduce a novel, cost-effective electrochemical method for manufacturing reusable and flexible shadow masks with ultrafine feature sizes. By combining electroplating techniques with the dry transfer method, we successfully produced metal masks with ultrafine features, which were then utilized to evaporate metal electrodes with micron feature sizes onto nanostructured substrates. These metal masks, with specifically designed patterns, were employed as etching masks to pattern monolayer MoS2 (a type of TMD) materials without the need for photoresists or solution processes. Moreover, the resulting metal mask-evaporated electrodes, with smooth edges, were integrated with atomic layer transition metal dichalcogenides through van der Waals interactions to create devices based on MoS2.