Patterned electrodeposition of interconnects using microcontact printing

Microcontact printing combined with electroless deposition is a potential low cost technique to make electrical interconnects for opto-electronic devices. Microcontact printed inhibitors locally prevent electroless deposition resulting in a pre-defined pattern of metal tracks. The inhibition of electroless Ni deposition on Pd-seeds and on indium tin oxide (ITO) by self-assembling molecules (SAM) was investigated. Polarisation measurements and transients show that on Pd seeds for electroless deposition, thiol-compounds inhibit the oxidation of the reducing agent, hypophosphite, in the electroless Ni bath. Cyclic voltammetry suggests that the inhibition is due to adsorption of the inhibiting molecules on active sites of the Pd-seeds only or as a SAM on the entire Pd seeds depending on the thiol-compound used. Polarization measurements show that after a pre-treatment in nitric acid hexadecylamine (HDA) is able to inhibit Ni electrodeposition on ITO. It was found that the pre-treatment activated ITO for Ni electrodeposition. Adsorbed HDA increases the crystallization overpotential for Ni electrodeposition by approximately 100 mV