An investigation on technologies to fabricate microcoils for miniaturized actuator systems

Abstract

Within the framework of the Collaborate Research Center "Design and Fabrication of Active Microsystems" (Sonderforschungsbereich 516), one aspect is the development of fabrication technology for driving coil systems to be applied to in electromagnetic microactuators. The two key focus areas are the fabrication of high aspect ratio, conductors and insulating them by applying planarizing polymer material. The research activities included the development of technologies like for UV depth lithography, electroplating through lithographic masks (galvanoforming), as well as embedding in and planarization by insulation material. Combining these technologies allows to create high aspect ratio integrated multilayer coils with integrated magnetic flux guiding structures. The materials applied were copper as a conductor, NiFe for magnetic cores and the negative tone resists SU-8 (MicroChem Corp.) as well as BCB (DOW Chemical) for insulation and embedding purposes. For electroplating molds, the DNQ/Novolak type photoresists AZ4562 and AZ9260 (Clariant) were utilized. The established technologies were integrated into process flows for fabricating thick and high aspect ratio planar and helical coils for electromagnetic linear actuators.