Electron beam lithography of Free-Standing Ni–Mn–Ga films

We present a process to fabricate freely movable shape memory alloy (SMA) structures by electron-beam lithography (EBL) and sacrificial layer technology starting from free-standing SMA films. Functional films such as SMA and ferromagnetic SMA films may not be structured on the same substrate used for deposition due to process incompatibilities. In addition, EBL and sacrificial layer technologies entail various constraints and requirements on substrate material and properties. These issues can be solved by introducing a substrate inversion technology that includes deposition of sacrificial structures followed by electroplating of a new metal substrate onto the functional film and release of the initial substrate. This process is demonstrated for a SMA film of NiMn-Ga that has been sputter-deposited on a polymer substrate allowing the fabrication of large arrays of mechanically active SMA nanostructures.