Effect of dislocation density on adhesion strength of electroforming Ni layer on Cu substrate

Adhesion plays a critical role in the reliability of the micro devices in MEMS. However, the quality of the micro devices fabricated by electroforming technology is influenced by the poor adhesion performance. In order to improve the poor adhesion performance, from the view of the dislocation density, this paper investigates the effect of the current density on the adhesion originally. To research the effect of the dislocation density, electroforming experiments were processed under two different current densities. The dislocation density and the compressive stress of the electroforming layer was measured by XRD method. The dislocation was observed by TEM method. The adhesion strength was tested by scratch test. The experimental results show that the small current density reduces the dislocation density and the compressive stress, increases the adhesion. The mechanisms are that the small current density reduces the dislocation density. The low dislocation density can reduce the compressive stress and increase the adhesion. This work can improve the adhesion of the electroforming layer.