Arrays of copper rings with tunable dimensions via electro-colloidal lithography

Electro-colloidal lithography (ECL) is an easy, fast, straightforward and cheap patterning process that has been used here to design patterned copper film. ECL consists in assembling polystyrene (PS) micro-beads in 2D hexagonal crystals onto an electrode using AC (Alternative Current) electric field, in sticking them onto the electrode surface where copper is then deposited using Cu2+-containing multi-lamellar vesicles (MLVs) submitted to a DC (Direct Current) electric field. Copper rings are then formed; their separation, ranging from 2 to 4.2 mu m, could be varied playing on either PS beads size or on AC electric field parameters (frequency and amplitude). The ring internal diameter (100-880 nm range), the ring height (28-400 nm range) as well as the copper film thickness (6-102 nm range) were controlled through the time of DC field application. AFM, SEM, microscopic imaging as well as mathematical modeling show that PS beads behave as a template for copper ring growth, and that this patterning is due to an accumulation of MLVs around the dielectric PS spheres on the electrode. (C) 2015 Elsevier B.V. All rights reserved.