Volcano‐Type Etch Rate Modulation by Magnetic Layer in Magnetic Metal‐Assisted Chemical Etching

This study employs magnetically guided metal‐assisted chemical etching (h‐MacEtch) to systematically investigate how the catalyst‐layer architecture, together with the catalyst (Au) and magnetic layer (Ni) thicknesses, influence the etching rate under an external magnetic field, using varied catalytic‐layer configurations. The primary focus is on the role of the magnetic Ni layer in enhancing the MacEtch reaction, supported by comprehensive experimental characterization and mechanistic analysis. Results indicate that the catalyst‐layer thickness modulates the etching rate, following a volcano‐type trend. The enhanced etching performance originates from optimizing the catalyst‐layer architecture, where the magnetic Ni interlayer provides regulation while maintaining efficient mass transport through a continuous yet moderately porous catalyst structure. By rationally designing the thickness combination of the Au and Ni layers, the etching rate was increased by 1.359–1.491‐fold compared to the conventional Ti‐Au MacEtch process used in our work. This work demonstrates that optimizing the magnetic layer thickness under an external magnetic field is a critical factor in enabling high‐rate h‐MacEtch, offering important insights for the efficient and high‐precision fabrication of semiconductor microstructures.