Coupling silicon lithography with metal casting

Abstract

Micron-scale shaped 2D or 2.5D structures made of silver or copper can be produced by combining silicon photolithographic etching with metal casting by pressure infiltration. This combination of two classical processes, one from semiconductor fabrication and the other from the metallurgical industries, combines advantages of lithography and casting, namely excellent dimensional control, high reproducibility, compatibility with engineering metals used in microtechnology, and the possibility for high production rates since many parts can be produced simultaneously at every step of the process. We demonstrate the production of 2D and 2.5D structures including monocrystalline tensile specimens, of diameter selected in the range from 2.5 to 13 μm. In-situ micromechanical tensile tests performed on those samples show that microcast metal structures produced via this approach exhibit characteristics of confined plasticity, namely increases, with decreasing sample diameter, in both the flow stress and deformation intermittency.