MAGNETICALLY DRIVEN MICROSTRUCTURES FABRICATED WITH MULTILAYER ELECTROPLATING

A new surface micromachining technology called '3D UV-microforming' wa s applied to fabricate three-dimensional components on silicon substra tes. The technology consists of an advanced resist preparation process , a UV lithographic step, resist development, a galvanic moulding proc edure for filling up the resist patterns and finally stripping and cle aning for finishing the structures. During resist preparation, layers up to 200 mu m thickness were obtained. By using a standard UV mask al igner as an exposure tool and followed by immersion development, thick resist layers up to 100 mu m could be patterned in a single shot on p re-processed silicon wafers. Repeated exposure and development were su ccessfully used for structuring resist layers of up to 200 mu m thickn ess. High aspect ratios of more than 10 as well as steep edges of more than 88 degrees could be fabricated. The resist patterns were moulded by using pulse or d.c. electroplating. For microactuator applications gold, copper and nickel-iron alloys were deposited. NiFe has excellen t, stainless-steel-like mechanical properties and is, additionally, fe rromagnetic. The magnetic and mechanical characteristics depend on the composition and can be varied with the process parameters. Some magne tically driven microcomponents, e.g. cantilevers for reeds and membran es for valves, were fabricated as demonstrators for the new technique.