Permanent magnet films for applications in microelectromechanical systems

This paper reviews several promising permanent magnet (PM) films used for the applications in microelectromechanical system (MEMS). Selection rules for PM films are elucidated. Currently in use or developing PM films, including rare-earth magnet alloys, transition-metal alloys and hard ferrites, are critically assessed. To meet the MEMS requirements, a permanent magnet film must possess, in addition to high magnetic performance at the service temperature, the adaptability to IC processing as well as environmental stability. Rare-earth magnet films showing the best magnetic performance are not necessarily the best choice for MEMS applications, due to the high corrosion rate. The PtFe or PtCo films and the hybrid-magnet thick-films (composed of a photo-lithographable resin and a magnet powder) show greater potential in future MEMS applications. (C) 2000 Elsevier Science B.V. All rights reserved.