Combining electroless filling with metal-assisted chemical etching to fabricate 3d metallic structures with nanoscale resolutions

This work introduces a simple process to fabricate 3D metallic structures with micro to nano-sized features. Star-shaped gold catalysts were fabricated using electron beam lithography and used as catalysts in MaCE to form spiraling 3D structures. High fidelity was verified by adding 30 nm wide holes in some catalysts for form 30 nm wide spiraling silicon pillars. The gold catalyst remaining at the bottom of the 3D MaCE template was used as a seed for electroless deposition of Pd and the resulting structure extracted using tetramethylammonium hydroxide to form a freestanding 3D metallic structure with nano-sized 3D spiraling holes.