Patterning conductive copper by nanotransfer printing

We describe a method for patterning conductive copper over large areas by nanotransfer printing (nTP). This technique is purely additive and yields feature sizes in the 1–500 μm range. Unlike gold patterns printed in a similar manner, oligomers from poly(dimethylsiloxane) (PDMS) stamps used in nTP permeate through the entire thickness of printed copper resulting in nonconductive patterns. Hot leaching the PDMS stamps in toluene prior to printing removes residual oligomers; printing with pretreated stamps reproducibly yields conductive copper patterns with an average resistivity of 31μΩ-cm.