Reducing the internal compressive stress of the microelectroformed layer by adjusting the current densities

Abstract

In the microelectromechanical systems area, micrometal devices can be fabricated by microelectroforming process. However, since the defect mechanism of crystal growth, the electroformed layer suffers from the large internal compressive stress. To reduce the large internal compressive stress, the effects of different current densities on the internal compressive stress are investigated. From the view of dislocation density, the mechanism to reduce the compressive stress by adjusting the current densities has been researched originally. The electroforming experiments were processed by several current densities. The dislocation density was measured by the X-ray diffraction method. The compressive stress was tested by side incline method. The nanocrystal structure was observed by the transmission electron microscopy method. The experimental results show that the dislocation density was decreased along with the decreasing of the current density, as well as the compressive stress. The mechanisms are that the crystal structures including the crystallite size, the microcrystal distortion and the dislocation density can be refined by adjusting the small current densities. Then, the compressive stress becomes lower. This work contributes to fabricate the electroformed layer with low internal compressive stress.