Preparation and characterization of microtubes of amorphous metallic thin film systems

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Amorphous metallic films exhibit lower surface roughness, better corrosion resistance and a higher elastic limit compared to crystalline metal films. Thus they can find application as new materials in thin film technology, namely for highly stressed micro-electro-mechanical systems (MEMS) or for sensor and actuator applications. A promising novel fabrication approach is the technique of self-assembling rolled-up micro tubes. The gradient of intrinsic film stress being necessary for rolling up has not been studied so far in detail for amorphous or amorphised metal films.In the present project, amorphous metal films and those crystalline film systems being able to react to amorphous layers shall be produced by magnetron sputtering and shall be characterized in regard to structure and stress state. From these layers, self-assisted rolled-up micro tubes shall be fabricated followed by an amorphisation reaction. Sacrificial layers structured appropriately by lithography are to be used in this step. Ni-Zr as a well-known binary metal system being able to amorphise in a solid state reaction is chosen in the first place. Subsequently, investigations are to be expanded to the Cu-Ti combination. The latter can also be deposited amorphously, furthermore it shows an increased electrical conductivity compared to Ni-Zr and better adhesion on Si.To get more detailed insights in the processes involved, the interface properties and the structure of the micro tubes rolled-up and amorphised shall be studied extensively, considering especially correlations to varied parameters of fabrication and stoichiometry. Further mechanical characteristics of the tubes are to be determined by compression and bending tests and by using a nanoindentation device.