Preparation of high aspect ratio surface microstructures out of a Zr-based bulk metallic glass

Silicon wafers with high aspect ratio surface microstructures, prepared by deep reactive ion etching and coated with a protective layer, are replicated into a Zr-based bulk metallic glass. Therefore, a new process route called hot mold quenching is developed. In this process, the bulk glass-forming alloy and the mold are heated to a temperature of 1350 K to allow complete wetting of the microstructured silicon mold by the melt. After a few seconds, the surface microstructures of high aspect ratio are filled by the melt completely. Mold and melt are then quenched together at a rate of 20 K/s to prevent crystallization in the Zr-Cu-Ni-Al-Ti melt. Subsequently, the wafer is removed by wet etching. Structures of 20 mum height, 8 mum width and a spacing of 1 mum have successfully been replicated into the metallic glass. Tools out of this material have a high strength, a high elastic limit and a good corrosion resistance, and meet the requirements for injection molding of polymers ideally. (C) 2003 Elsevier Science B.V. All rights reserved.