Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Magnetic shape memory alloys are emerging multifunctional materials that enable applications
like high-stroke actuation, solid-state refrigeration, and energy harvesting of waste heat. Thin
films of these alloys promise integration in microsystems to exploit their multifunctional
properties at the microscale. However, the microfabrication process of these Heusler alloys is
difficult. Here, we investigate different etching techniques for the microfabrication of epitaxial
Ni-Mn-Ga films, explain the encountered challenges, and demonstrate ways to overcome them.
Our results show that wet chemical etching is suitable for large patterned structures, while
reactive ion etching of Ni-Mn-Ga films is unsuitable due to redeposition. For patterning
structures below 10 μm with clean and sharp edges, the best results are obtained by ion-beam
etching with adjusted sample-stage tilt. Finally, we demonstrate a microfabrication process
using Si microtechnology to fabricate partially free-standing structures. Our findings give
guidelines for the fabrication and integration of these smart materials in Si-based microsystems.