Materials and Fabrication Methods for High Temperature Micro-Magnetic Machines for Micro-Turbine Power Generation

Abstract : This paper presents recent advances in the development of materials and fabrication methods for high temperature (400 - 900 C) magnetic micro-machine for electrical power generation. Suitable materials and material compatibility issues are identified for the device conductors, magnetic cores, and bulk structure. Two fabrication methods for encapsulating electroplated structures inside fusion bonded silicon wafers are presented. These fabrication techniques enable the integration of thick conductive and magnetic materials into multi-wafer silicon MEMS devices. Electrical tests verify the integrity of electroplated Cu conductors after wafer bond annealing and mechanical tests confirm that the presence of the metal does not adversely affect the bond strength. Preliminary results of electrodeposited ferromagnetic Fe-Co materials are also discussed.