Fabrication of Electrodeposited Ni–Fe Cantilevers for Magnetic MEMS Switch Applications

Electrodeposited alloys of nickel and iron are prone to suffer from the development of undesirable-stress gradients resulting from process steps and heat treatments following deposition. As a result, the yield associated with devices using permalloy (Ni-Fe, 80%-20%) films can be severely compromised. Although electrodeposition recipes have been formulated that greatly reduce stress in Ni-Fe films, any stress gradients through the thickness of permalloy can pose considerable problems during the release of cantilevers. The development of such gradients is typically the direct result of the selected design and process architecture and/or problematic material choices. This paper presents an improved architecture for electroplated Ni-Fe freestanding microcantilever structures. This architecture minimizes the development of stress gradients in cantilever beams and facilitates the use of suspended permalloy cantilever structures in magnetically actuated microelectromechanical systems (MEMS) switches.