Subtractive Patterning via Chemical Lift-Off Lithography

Abstract

Patterning by Subtraction Soft lithographic patterning is usually a “positive” inking process. A polymer stamp is cured on a hard master substrate and then inked with molecules such as alkane thiols, which can then be transferred to a second substrate (such as gold). However, the resolution of the transferred pattern is often degraded by surface diffusion. Liao et al. (p. 1517 ; see the Perspective by Rogers ) obtained higher resolution in a subtractive approach, in which oxygen-plasma–activated silicone stamps removed hydroxyl-terminated alkane thiols from gold surfaces. This lift-off process also removed the terminal gold atom bound to the alkane thiol. The bare regions could be backfilled with protein molecules, and multiple lift-off steps could create patterns with features as small as 40 nanometers.