Selective wet-etching of microcontact-printed Cu substrates with control over the etch profile

Abstract

Employing self-assembled monolayers (SAMs) as resists necessitates highly selective etch systems: these resists, which can be patterned using mirocontact printing (μCP), are fragile systems because they cover a substrate with a molecular layer that is only a few nm thick and are prone to having defects such as missing molecules. Increasing the size of etchants helps to tolerate such defects in monolayers and enables microcontact-printed substrates to be etched with very high selectivity. Adding monolayer-forming molecules to an etch bath that can 'heal' defects in a printed SAM is another practical method to achieve high selectivity, and provides a means to form tapered structures. The latter effect relies on the continuous propagation of a self-assembling etch barrier from the printed area competing with vertical etching. These improvements turn defective monolayers into robust resist systems, and extend the patterning possibilities of μCP, allowing, for example, repetitive printing and etching operations on substrates to shape the profile of structures, or to form multilevel patterns. © 2003 Elsevier Science B.V. All rights reserved.