Scotch Magic Tape for smaller and better electronics

Researchers have discovered a groundbreaking technique in manufacturing nanostructures that has the potential to make electrical and optical devices smaller and better than ever before. A surprising low-tech tool of Scotch Magic Tape ended up being one of the keys to the discovery by a group of researchers from the University of Minnesota, Argonne National Laboratory and Seoul National University.

Combining several standard nanofabrication techniques - with the final addition of the Scotch Magic Tape - researchers at the University of Minnesota created extremely thin gaps through a layer of metal and patterned these tiny gaps over the entire surface of a 4″ silicon wafer. The smallest gaps were only one nanometre wide, much smaller than most researchers have been able to achieve. In addition, the widths of the gaps could be controlled on the atomic level. This work provides the basis for producing new and better nanostructures that are at the core of advanced electronic and optical devices.

One of the potential uses of nanometre-scale gaps in metal layers is to squeeze light into spaces much smaller than is otherwise possible. Collaborators at Seoul National University, led by Prof Dai-Sik Kim, and Argonne National Laboratory, led by Dr Matthew Pelton, showed that light could readily be squeezed through these gaps, even though the gaps are hundreds or even thousands of times smaller than the wavelength of the light used. Researchers are very interested in forcing light into small spaces because this is a way of boosting the intensity of the light. The collaborators found that the intensity inside the gaps is increased by as much as 600 million times.

Scotch Magic Tape was one of the keys to the discovery. Etching one-nanometre-wide gaps into metals is not feasible with existing tools. Instead, the researchers in Oh’s team constructed the nanogaps by layering atomic-scale thin films on the sides of metal patterns and then capping the structure with another metal layer. No expensive patterning tools were needed to form the gaps this way, but it was challenging to remove the excess metals on top and expose the tiny gaps. During a frustrating struggle of trying to find a way to remove the metal films, University of Minnesota PhD student and lead author of the study Xiaoshu Chen found that by using simple Scotch Magic Tape, the excess metals could be easily removed.

This research was funded by the US Department of Defense (DARPA Young Faculty Award and the ONR Young Investigator Program), the US Department of Energy and the National Research Foundation of Korea with capital equipment funding from the Minnesota Partnership for Biotechnology and Medical Genomics.