Conductive copper patterns by an additive, solventless, contact printing technique

An alternative copper patterning technique, nanotransfer printing, that is purely additive, solventless, and can be carried out at ambient conditions, was investigated. Deposition of copper onto the raised and recessed regions of the poly(dimethylsiloxane) (PDMS) stamp occurs by e-beam evaporations. Instantaneous reaction between the unreacted thiol endgroups of octanedithiol and copper occurs at the interface resulting in permanent copper attachment to the GaAs substrate. Preliminary AFM investigation of the printed metal surfaces indicated that PDMS oligomers might be able to permeate between individual copper grains thereby disrupting the percolative pathway of conduction.