Printing of highly integrated crossbar junctions
Soft organic, polymeric or biological material promise new functionalities e.g. switching or specific recognition reactions applicable for memory elements or biosensors, respectively. Appropriate fabrication strategies require avoiding process conditions harmful for the sensitive soft materials. Researchers at Sony Deutschland GmbH and the Forschungszentrum Jülich have developed together a new route for the realization of organic-inorganic heterojunctions that combines Nanoimprint lithography with a universal and gentle printing method. The feasibility of this process is demonstrated by the incorporating conductive polymer films into the cross points redundant and failure tolerant 8x8bit crossbar arrays.
Nils Sanetra, Zoi Karipidou, René Wirtz, Nikolaus Knorr, Silvia Rosselli, Gabriele Nelles, Andreas Offenhäusser and Dirk Mayer
Abstract: In this publication, a new process is presented that combines nanoimprint lithography and soft lithography to assemble metal–bridge–metal crossbar junctions at ambient conditions. High density top and bottom metal electrodes with half-pitches down to 50 nm are fabricated in a parallel process by means of ultraviolet nanoimprint lithography. The top electrodes are realized on top of a sacrificial layer and are embedded in a polymer matrix. The lifting of the top electrodes by dissolving the sacrificial layer in an aqueous solution results in printable electrode stamps. Crossbar arrays are noninvasively assembled with high yield by printing the top electrode stamps onto bare or modified bottom electrodes.
A semiconducting and a quasi metal like conducting type of polymer are incorporated in the cross points to form metal-polymer-metal junctions. The electrical characterization of the printed junctions revealed that the functional integrity of the electrically addressed conductive polymers is conserved during the assembling process. These findings suggest that printing of electrodes represents an easy and cost effective route to highly integrated nanoscale metal-bridge-metal junctions if imprint lithography is used for electrode fabrication.
Advanced Functional Materials, March 21, 2012, Volume 22, Issue 6 (pages 1129–1135)
Article first published online: 10 JAN 2012 | DOI: 10.1002/adfm.201101925