Preparation and characterization of microtubes of amorphous metallic thin film systems

与晶态金属薄膜相比，非晶态金属薄膜具有更低的表面粗糙度、更好的耐腐蚀性和更高的弹性极限。因此，它们可以作为新材料应用于薄膜技术，即用于高应力微电子机械系统(MEMS)或传感器和执行器应用。自组装卷起微管技术是一种很有前途的新型制备方法。对于非晶态或非晶态金属薄膜，目前还没有详细研究卷起所需的本征薄膜应力的梯度。在本项目中，非晶态金属薄膜和那些能够与非晶层发生反应的晶态薄膜系统将通过磁控溅射来制备，并从结构和应力状态方面进行表征。从这些层，自助式卷起的微管将被制造出来，然后进行非晶化反应。在该步骤中将使用通过光刻适当构造的牺牲层。镍-锆作为一种著名的二元金属系统，能够在固态反应中非晶化，因此首先被选择。随后，研究将扩大到铜-钛组合。后者也可以无定形沉积，此外，与Ni-Zr相比，它的导电性更高，在Si上的附着力更好。为了更详细地了解所涉及的过程，需要广泛研究卷起和非晶化的微管的界面属性和结构，特别是考虑到不同的制造参数和化学计量比之间的相关性。管子的进一步机械特性将通过压缩和弯曲试验以及通过使用纳米压痕装置来确定。

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.