Nanoscale 3D Electroforming by Template Pyrolysis

Gunderson, Christopher; Rohbeck, Nadia; Tranchant, Maxime; Michler, Johann; Philippe, Laetitia

Advanced Engineering Materials 23 (2021)

A novel approach is demonstrated that extends the resolution of 3D electroforming. Photoresist templates with complex 3D geometries are generated using two-photon lithography are shrunken by a factor of ≈5 through pyrolysis. A key discovery is that pyrolysis at 500 °C, instead of the higher temperatures normally used for pyrolysis, still shrinks the template by a significant amount but keeps the template nonconductive. This shrunken template is used for electroforming, or template-assisted electrodeposition, and then etched away to reveal complex 3D structures of pure metal (>99 at%) with linewidths below 200 nm. The versatility of the technique is demonstrated by fabricating octet truss nanolattices from either nanocrystalline gold or microcrystalline copper. In situ micromechanical tests are used as an analytical technique to reveal that these lattices have yield strengths of 325 and 190 MPa for the gold and copper, therefore verifying the fidelity of the architecture.