Cobalt and iron segregation and nitride formation from nitrogen plasma treatment of CoFeB surfaces.
Cobalt-iron-boron (CoFeB) thin films are the industry standard for ferromagnetic layers in magnetic tunnel junction devices and are closely related to the relevant surfaces of CoFe-based catalysts. Identifying and understanding the composition of their surfaces under relevant processing conditions is therefore critical. Here we report fundamental studies on the interaction of nitrogen plasma with CoFeB surfaces using infrared spectroscopy, x-ray photoemission spectroscopy, and low energy ion scattering. We find that, upon exposure to nitrogen plasma, clean CoFeB surfaces spontaneously reorganize to form an overlayer comprised of Fe2N3and BN, with the Co atoms moved well below the surface through a chemically driven process. Subsequent annealing to 400 °C removes nitrogen, resulting in a Fe-rich termination of the surface region.
Materials Science Department, University of Texas at Dallas, 600 W. Campbell Rd., Richardson, Texas 75080, USA.
E C
EC
Mattson
Components Research, Intel Corporation, Hillsboro, Oregon 97124, USA.
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000000021226608X
DJ
Michalak
Materials Science Department, University of Texas at Dallas, 600 W. Campbell Rd., Richardson, Texas 75080, USA.
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0000000237435521
JF
Veyan
Materials Science Department, University of Texas at Dallas, 600 W. Campbell Rd., Richardson, Texas 75080, USA.
Y J
YJ
Chabal