Atomic-scale analysis of CoFe/Cu and CoFe/NiFe interfaces

Internal interfaces in metallic multilayers grown on planar silicon substra tes have been chemically analyzed with atomic resolution using three-dimens ional atom probe microscopy. The structure studied was a NiFe/CoFe/Cu/CoFe multilayer grown with (111) texture. Atom probe measurements across the NiF e/CoFe interfaces yield widths of 1.1 +/- 0.2 nm for NiFe grown on CoFe and 1.7 +/- 0.2 nm for CoFe grown on NiFe, The widths of interfaces between Co Fe and Cu layers vary as well, with values of 0.82 +/- 0.10 nm for CoFe gro wn on Cu, but only 0.47 +/- 0.15 nm for Cu grown on CoFe. In addition, the Fe concentration is enriched at the interface where Cu is grown on CoFe, an d depleted when CoFe is grown on Cu. These results indicate that the Fe seg regates to the surface during the deposition of CoFe so that the compositio n at the top of this layer is Fe rich. (C) 2000 American Institute of Physi cs. [S0003-6951(00)02629-2].