Nanolithography, the process of carving circuits into computer chips far smaller than the electronic components currently embedded in digital devices, could produce faster, more powerful processors. Unfortunately, every process of nanolithography remains too expensive and too slow for commercial applications.
Enter beam-pen nanolithography. By using tiny beams of light, this method offers a means to rapidly and inexpensively make and prototype circuits, optoelectronics and medical diagnostics, doing for nanofabrication what the desktop printer has done for printing.
“It’s all about miniaturization,” said Chad Mirkin, director of Northwestern University’s International Institute for Nanotechnology. “Rapid and large-scale transfer of information drives the world. But conventional micro- and nanofabrication tools for making structures are very expensive. We are trying to change that with this new approach to photolithography and nanopatterning.”
Using this technique, scientists at Northwestern University patterned 15,000 replicas of the Chicago skyline, simultaneously, in about half an hour. Fifteen thousand tiny light pens deposited the skylines over square centimeters of space. Conventional nanolithography technologies, such as electron-beam lithography, allow one to make similarly small structures, but have an inherently low throughput and does not allow for large-area fabrication.
Each pen is in the shape of a pyramid, with the point as its tip. The researchers coat the pyramids with a very thin layer of gold and then remove a tiny amount of gold from each tip. The large open tops of the pyramids (the back side of the array) are exposed to light, and the gold-plated pyramids channel the light to the tips. A fine beam of light comes from each tip, where the gold was removed, exposing the light-sensitive material at each point. This allows the researchers to print patterns with great precision and ease.
Beam-pen lithography could lead to the development of a desktop printer of sorts for nanofabrication, giving individual researchers a great deal of control of their work.