Micromolding three-dimensional amorphous metal structures

Abstract

In this article, we report a simple and inexpensive approach to micromolding of complex, three-dimensional, high aspect ratio structures (with non-line-of-sight features) out of a high-strength amorphous metal. Inexpensive sacrificial silicon molds were created using lithography and etching techniques originally developed for integrated circuit production by the microelectronics industry and later adopted for microelectromechanical (MEMS) manufacturing. Multiple silicon layers were stacked, and the metallic glass was forced into the cavities under heat and pressure in an open air environment. Following cooling, the metallic structures were released by etching the silicon away in a potassium hydroxide (KOH) bath. Process studies showed that temperature is the most significant variable governing mold-filling. Transmission electron microscopy (TEM) sections of the mold/glass interface showed successful replication of features with characteristic dimensions on the order of 10 nanometers and no discernible gap between the silicon and the metallic glass. This scalable micromolding process leverages the inexpensive and readily available aspects of silicon lithography to economically support the mass customization (low volume production) of metal microcomponents without elaborate infrastructure needs.