Electroplating of low stress permalloy for MEMS

With the wafer-bending method and spectrophotometry, the internal stress in electroplated Ni–Fe alloy for MEMS has been investigated as a function of bath concentration. This investigation demonstrated that low concentration plating solution is useful for the decrease of the residual stress in the electrodeposits, and the stress could further decrease with an increase of saccharin additive content. And the change of stress from tensile to compressive was not observed with the increase of the additive content in plating path. The low stress permalloy (Ni81Fe19) was reached in our experimental conditions. A bistable electromagnetic RF MEMS switch with deformation-free bilayer cantilever beam was fabricated successfully by electroplated permalloy.