Electrodeposited magnetic alloys for surface micromachining

Electrodeposited magnetic materials are of great interest in surface micromachining as they can be used for transformation of forces in both actuators and sensors. Magnetic alloys of the ferrous metal family with different characteristics can readily be electrodeposited. An advanced lithographic process was performed in order to generate resist molds for electrodeposition. By means of standard ultraviolet aligners and immersion development photoresist layers up to 80 mu m were patterned in a single shot. Repeated exposure and development were successfully used for structuring thicker resist layers. High aspect ratios and steep edges were achieved with a sufficiently high resolution. The resulting resist patterns were molded via electroplating. For microsystem applications, magnetic alloys such as NiFe and NiCo are of special interest. The deposited material was characterized in relation to its mechanical and magnetical properties. Some examples of microsystem components using magnetic properties are given. The active part of a magnetically driven microvalve containing a membrane with integrated force amplifier from NiFe alloy as well as a microturbine with NiCo rotator were fabricated and tested.