The patterning of nickel-titanium SMA films with chemical etching by a novel milticomponent etchant

The patterning of nickel-titanium SMA thin films was one of critical micromachining issues during developing SIMA film devices, now, an excellent etchant for etching of Ni-Ti SMA thin films was developed, therefore, this problem can be solved by photochemical etching easily. The etchant is based on the dilute hydrofluoric acid with several kinds of additives. The etching process is operated at room temperature with the etching rate of (1 similar to 5) mu m/Min., The etched surface is very smooth and the edge of patterned SMA line is exactly the same as that of patterned photoresist. The etch factor is above 1.5 and might be enlarged furthermore. The etchant is stable and the repeatability is also good This patterning method is compatible with IC processes, so it is easy to design and fabricate any magic pattern for MicroElectroMechanical System(MEMS) applications.