Self-assembly-based batch fabrication of nickel-iron nanowires by electroplating

Abstract

The reason behind the majority of difficulties encountered in the integration of nanoscale objects with microelectromechanical systems can almost always be traced back to the lack of batch-compatible fabrication techniques at the nanoscale. On the one hand, self-assembly products do not allow a high level of control on their orientation and numbers, and hence, their attachment to a micro device is problematic. On the other hand, top-down approaches, such as e-beam lithography, are far from satisfying the needs of mass fabrication due to their expensive and serial working principle. To overcome the difficulties in micro-nano integration, a batch-compatible nanowire fabrication technique is presented, which is based on fabricating nanowires using simple lithographic techniques and relying on guided self-assembly. The technique is based on creating cracks with a predetermined number and orientation in a thin SiO2 coating on Si substrate, and then filling the cracks with an appropriate material of choice. After the SiO2 coating is removed, nanowires remain on the Si surface as a replica of the crack network. The technique, previously confined to electroless deposition, is now extended to include electroplating, enabling the fabrication of nanowires of various alloys. As an example, arrays of NiFe nanowires are introduced and their magnetic behaviour is verified.