The double-side electroplating and slender ferromagnetic patterns torque-enhancement design for magnetostatic actuator

This study demonstrates the torque-enhancement design for magnetostatic actuators driven by double-side electroplating ferromagnetic film. The present design has two merits: (1) the backside electroplating of the ferromagnetic film increases the magnetostatic torque, (2) the slender ferromagnetic material patterns with higher length-to-width ratio enhance the magnetostatic torque. The actuator is implemented on SOI wafer, and the process also has two merits, (1) the device-layer act as the cathode to enable simultaneous double-side electroplating, (2) the handle-layer is exploited as the shadow mask to pattern the seedlayer at backside wafer. In applications, a scanner were implemented and characterized. Measurements show a 149% torque enhancement from double-side electroplating design. The vertical slender ferromagnetic material patterns further increase the magnetostatic torque to 211%.