Development of hybrid microdevices composed of Ni-Mn-Ga and silicon layers: fabrication and metrology

Abstract

Extensive research and development efforts have established Ni-Mn- Ga as a promising smart material. However, its practical applications as a sensing and actuating material still need to be improved. Several challenges impede the standalone use of Ni- Mn-Ga, including the difficulty in growing large-sized single crystalline ingots via existing crystal growth methods, the lack of scalable fabrication processes, and the inherent brittleness of the material, impede the standalone use of Ni-Mn-Ga.

To overcome these limitations, this research proposes hybrid microdevices combining Ni-Mn-Ga and silicon (Si) materials. Ni-Mn-Ga is used as the active part of the microdevice, whereas the Si chip is employed as the inactive part and performs supplementary functions, such as accommodating microfluidic channels and device housing. Fabrication of these hybrid microdevices involves microelectromechanical systems (MEMS) technologies.

This study explores critical aspects of Ni-Mn-Ga fabrication, including etching, ion-implantation, wire sawing, grinding, polishing, and surface roughness measurement, of Ni-Mn-Ga synthesis. Additionally, comprehensive studies are conducted on Si surface defect classification and geometric parameters, as precise characterization of these aspects is vital for ensuring robust Si-to-Si and Si-to-Ni-Mn-Ga materials bonds.

This research represents a pivotal progression in microdevice engineering as it introduces a novel Ni-Mn-Ga-based micropump integrated with MEMS semiconductor chips, as demonstrated in Publications IV and this dissertation. Furthermore, the proposed hybrid microdevices hold the potential for diverse applications in sensing and actuation.

In conclusion, this study paves the way for the practical applications of Ni-Mn- Ga by overcoming the limitations of Ni-Mn-Ga via combining it with Si materials and developing innovative hybrid microdevices that combine the unique properties of both Ni-Mn-Ga and Si materials. By introducing new fabrication processes and metrology techniques, this research opens exciting opportunities for the integration of Ni-Mn-Ga with MEMS technology, fostering further advancements in microdevice engineering and smart material applications.