Advances in using amorphous metal alloys may make possible an inexpensive nanotech version of the molding technique used to make DVDs. The pits stamped in DVDs are rectangles 320 by 400 nm, but now amorphous metals have been used to stamp features as small as 13 nm, and the researchers believe that they can further decrease the feature size, perhaps to as small as single atoms. From Yale University, via AAAS EurekAlert “Yale engineers revolutionize nano-device fabrication using amorphous metals“:
Yale engineers have created a process that may revolutionize the manufacture of nano-devices from computer memory to biomedical sensors by exploiting a novel type of metal. The material can be molded like plastics to create features at the nano-scale and yet is more durable and stronger than silicon or steel. The work is reported in the February 12 issue of Nature [abstract].
The search for a cost-effective and manageable process for higher-density computer chip production at the nano-scale has been a challenge. One solution is making nano-scale devices by simple stamping or molding, like the method used for fabricating CDs or DVDs. This however requires stamps or master molds with nano-scale features. While silicon-based molds produce relatively fine detail, they are not very durable. Metals are stronger, but the grain size of their internal structure does not allow nano-scale details to be imprinted on their surfaces.
Unlike most metals, “amorphous metals” known as bulk metallic glasses (BMGs) do not form crystal structures when they are cooled rapidly after heating. Although they seem solid, they are more like a very slow-flowing liquid that has no structure beyond the atomic level — making them ideal for molding fine details, said senior author Jan Schroers of the Yale School of Engineering & Applied Science.
Researchers have been exploring the use of BMGs for about a decade, according to Schroers. “We have finally been able to harness their unusual properties to transform both the process of making molds and producing imprints,” he said. “This process has the potential to replace several lithographic steps in the production of computer chips.”
Schroers says BMGs have the pliability of plastics at moderately elevated temperatures, but they are stronger and more resilient than steel or metals at normal working temperatures.
“We now can make template molds that are far more reliable and lasting than ones made of silicon and are not limited in their detail by the grain size that most metals impose,” said Schroers.