Patterning of alkanethiolate self-assembled monolayers by downstream microwave nitrogen plasma: Negative and positive resist behavior

Abstract

Taking octadecanethiolate self-assembled monolayers (SAMs) adsorbed on Au(111) as a test system, the authors demonstrated patterning of an aliphatic monomolecular resist by downstream microwave nitrogen plasma in proximity printing geometry with a mesh mask simply placed onto the SAM surface. The behavior of the SAM resist was found to be dependent on the plasma treatment time, which is related to the dominance of different plasma-induced processes at different treatment stages. At a short treatment, the most prominent process is the activation of the SAM-ambient interface, resulting in subsequent adsorption of airborne species onto the plasma-exposed areas upon the exposure of the SAM pattern to ambient. At a long treatment, the dominant process is the chain decomposition with the subsequent desorption of the released fragments and carbonization of the residual film. Due to the above behavior, aliphatic SAMs can serve as either negative or positive monomolecular resists at either a short or long plasma treatment, as soon as the fabricated pattern is transferred to the underlying substrate.