Microfabrication of 3D multidirectional inclined structures by UV lithography and electroplating

A new process for the fabrication of 3D multidirectional inclined structures is presented. Based on a modified W exposure of commercially available thick positive photoresist and electrodeposition, this process can be carried out using common clean room equipment. To realise inclined structures, inclined rotating exposures are performed through two shifted masks integrated in the photoresist layers. By adequate shifts between the apertures of both masks, this new technique allows three dimensional structures inclined in any direction and with different tilt angles to be fabricated on the same substrate. This paper deals with the different fabrication steps and the simulation required for the accurate determination of several of the parameters needed for the masks. These parameters, such as the dimensions of the apertures, the shift angles between them or the thickness of the separation layer between the two masks have to be determined for each different tilt angle of the structures. By this new process, 10° inclined structures with heights up to 120 μm and with nearly parallel sidewalls have been fabricated. This technology opens a wide range of new applications. In particular, a first prototype of a new rotor for the Elastic Force Motor (EFM) has been fabricated by electroplating tilted legs on a previously electroplated wheel