Vertical coffee-stain method for forming self-organized line structures

Abstract

A 'vertical' coffee-stain method for producing self-organized line structures and other very fine features that involves disposing a target structure in a solution made up of a fine particle solute dispersed in a liquid solvent such that a 'waterline' is formed by the upper (liquid/air) surface of the solution on a targeted linear surface region of the substrate. The solvent is then caused to evaporate at a predetermined rate such that a portion of the solute forms a self-organized “coffee-stain” line structure on the straight-line portion of the substrate surface contacted by the receding waterline. The substrate and staining solution are selected such that the liquid solvent has a stronger attraction to the substrate surface than to itself to produce the required pinning and upward curving waterline. The target structure is optionally periodically raised to generate parallel lines that are subsequently processed to form, e.g., TFTs for large-area electronic devices.