Permanent magnet films for applications in microelectromechanical systems

Abstract 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.

[1]  Y. Yao,et al.  MICROSTRUCTURAL AND MAGNETIC STUDIES OF MN-AL THIN FILMS , 1997 .

[2]  CrMn underlayers for CoCrPt thin film media , 1998 .

[3]  T. Chin,et al.  Magnetic properties and interaction effect in sputtered Nd/sub 2/Fe/sub 14/B films , 1997 .

[4]  C. Ahn,et al.  Micromachined thick permanent magnet arrays on silicon wafers , 1996 .

[5]  T. D. Cheung,et al.  Directly sputter synthesized high‐energy product Sm‐Co based ferromagnetic films , 1985 .

[6]  G. Hadjipanayis,et al.  CoPt/Ag nanocomposites for high density recording media , 1998 .

[7]  T. Chin,et al.  High Coercivity Fe-Cr-Co Thin Films by Vacuum Evaporation , 1991 .

[8]  G. A. Prinz,et al.  Erratum: ‘‘Permanent magnet film magneto‐optic waveguide isolator’’ [J. Appl. Phys. 75, 6286 (1994)] , 1995 .

[9]  C. Bajorek,et al.  Permanent magnet films for biasing of magnetoresistive transducers , 1975 .

[10]  Recent advances in pseudobinary iron based permanent magnets , 1995 .

[11]  M. Madou.  Fundamentals of microfabrication , 1997 .

[12]  Eric E. Fullerton,et al.  Structure and magnetic properties of exchange-spring Sm–Co/Co superlattices , 1998 .

[13]  J. Liu,et al.  High energy products in rapidly annealed nanoscale Fe/Pt multilayers , 1998 .

[14]  Y. Tamaura,et al.  Ferrite plating in aqueous solution: New technique for preparing magnetic thin film , 1984 .

[15]  S. Suzuki,et al.  Sm/sub 2/Fe/sub 17/N/sub x/ bonded magnets with high performance , 1993 .

[16]  H. Hegde,et al.  Film Sm-Co permanent magnets for the biasing of thin permalloy strips , 1993 .

[17]  T. D. Cheung,et al.  High i H c perpendicular anisotropy Nd -Fe-B sputtered films , 1986 .

[18]  K. Watanabe,et al.  Al substituted Ba ferrite films with high coercivity and excellent squareness for low noise perpendicular recording layer , 1999 .