Introducing Water Electrolithography

Abstract

High-resolution patterning with remarkable customizability has stimulated the invention of numerous scanning probe lithography (SPL) techniques. However, frequent tip damage, substrate-film deterioration, low throughput, and debris amassing in the patterned region are the inherent impediments that have precluded obtaining patterns with high repeatability using SPL. Hence, SPL still has not got wider acceptance for industrial fabrication and technological applications. Here, we introduce a novel SPL technique, named water electrolithography (W-ELG), for patterning at the microscale and potentially at the nanoscale also. The technique operates in the non-contact mode and is based on the selective etching, via an electrochemical process, of a metallic film (e.g., Cr) submerged into water. Here, the working of W-ELG is demonstrated by scribing a pattern into the Cr film by a traversing cathode tip along a preset locus. A numerical analysis establishing the working principles and optimization strategies of W-ELG is also presented. The tip-sample distance and tip-diameter are identified as the critical parameters controlling the pattern creation. W-ELG achieved a throughput of 1.5 × 107 μm2/h, which is the highest among the existing SPL techniques, while drawing 4 μm wide lines, and is also immune to deleterious issues of tip damage, debris amassment, etc. Therefore, the resolution of these inherent impediments of SPL in W-ELG sets the stage for a paradigm shift that may now translate the SPL from academic exploration to industrial fabrications.

Electric current-assisted manipulation of liquid metals using a stylus at micro-and nano-scales

“…However, the presently available techniques lack the versatility of usage at different length scales for multiple purposes. Furthermore, arbitrary liquid metal transfer in precise quantities (in nL and below) is essential in many applications, such as drug delivery [14], patterning [15][16][17], coating [18], repair of open circuits [19], lithography [20,21], etc. In this context, we demonstrate here electric current-driven liquid metal transport at very small scales.…”

“…from a few nanometers to a few centimeters) in a preset direction [22][23][24]26]. Liquid electromigration has been studied in terms of its physics [22][23][24] and possible applications [20,21,26]. If this phenomenon is controlled, it may bear several applications, such as conformal coating, direct patterning of complex standalone structures, etc [22,[26][27][28].…”