Electrodeposition of low residual stress CoNiMnP hard magnetic thin films for magnetic MEMS actuators

A new technique for electrodeposition of CoNiMnP hard magnetic thin films is developed to provide thin films with low residual stress and magnetic properties useful for MEMS applications. Processing parameters including applied current density, film thickness, pH and temperature of the electrolyte are regulated in order to reduce residual stress of the film. In addition, a hybrid residual stress reliever composed of sodium saccharine and a rare-earth salts mixture of Ce2(SO4)3 and Nd2(SO4)3 is created to further reduce the residual stress, eliminate microcracks and improve surface morphology of the film. The effects of residual stress on the magnetic properties of electrodeposited CoNiMnP hard magnetic films such as coercivity, saturation and residual magnetization are reported in this paper