Effect of Angular Deposition of Ti Interlayer and Ag-Pd-Cu Final Layer on MEMS Surfaces Adhesion

The adhesion force is a critical factor in MEMS (micro-electro-mechanical systems) technology, especially in the micro-assembly process using microgrippers. Given the diminutive size and weight of MEMS devices, the contact force between the surfaces of MEMS components can lead to several problematic scenarios during the assembly procedure, such as the undesirable adhesion of the MEMS surface components. This can negatively affect the assembly procedure and result in incorrect positioning of microparts. Therefore, reducing the adhesion force is essential for enhancing micro-assembly. This research aimed to explore the impact of angularization of the interstitial layer and the last layer on surface morphology, surface roughness parameters, and adhesion using the glancing angle deposition method. To achieve this, six samples were simultaneously layered with varying experimental angles of 0, 30, 45, 60, 75, and 85 degrees for the deposition of thin films. These films comprised a titanium interstitial layer and the main layer Ag-Pd (0.9 wt.%)-Cu (1.0 wt.%). Following the glancing deposition, the morphology of the films was examined using SEM, while the layer roughness and adhesion force were determined using AFM. The findings of this study revealed that increasing the angle of the referenced layer resulted in an initial increase and subsequent decrease in both the grain height and surface roughness of the silver alloy. The tests showed that the angle of 85 degrees corresponded to the lowest level of adhesion observed in both experiments. In conclusion, it can be inferred that adjusting the angulation of the Ti interstitial layer in relation to the angulation of the last layer of the silver alloy results in improved grain size distribution, increased grain height, and enhanced regularity in surface adhesion behavior.