University of Wisconsin Stevens Point1, Chemistry, Stevens Point, WI 54481 Argonne National Laboratory2, CNM, Argonne, IL 60439
Electroplate-and-Lift (E&L) lithography, which was developed in 2010 by students at UW-Stevens Point in collaboration with scientists at Argonnne National Laboratory, is a fast, simple, scalable technique for the production of patterned metallic and semiconducting nanowires. In E&L, nanowires are electrodeposited on a lithographically patterned template, and then mechanically lifted away from the surface to regenerate the template for subsequent depositions. The choice of polymer adhesive plays a critical role in this 'lift' step. Currently, liftoffs are performed manually using scotch tape. However, as E&L is scaled up to a roll-to-roll, continuous production process, more practical adhesive alternatives will be required.
The choice of an appropriate adhesive, which may vary with the material being deposited, could be made much more systematic by the development of a reproducible, quantitative technique for measuring the strength of adhesive forces. Toward this end, a mechanical wire pull testing instrument has been adapted to lower a metal object (intended to simulate a collection of metal nanowires) onto an adhesive-coated PDMS substrate, and then measure the force required to lift the object straight up off the surface. The effects of variables, such as the mass of the metal object and its surface area of contact with the adhesive, are measured. This will ultimately allow the selection of adhesives with well known, desirable properties, such as adhering more strongly with the wires than to the template. The development of this technique allows us to quantify the adhesive interactions and test the reproducibility of many lift off techniques.
[Abstract (DOCX)]