| Title |
Heterogeneities of Cobalt - Based Thin Films by Sputtering Conditions (2) ( Compositional Heterogneities ) |
| Abstract |
Sputter deposited CoB and CoZrNb thin films have structural and compositional heterogeneities consisted of cobalt-rich particles and oxide-rich boundaries. The origin of the heterogeneities are considered as the oxygen incorporation into thin films during sputter deposition as shown in TEM morphological differences between CoB alloy films and pure Co films, between CoZrNb alloy films deposited without and with substrate bias, and between Co-based films before and after postdeposition annealing. The compositional heterogeneities are verified directly and indirectly by several experimental methods. One indirect method is the observation of different contrast of particles and boundaries in TEM micrographs. Measurement of the Curie temperature in CoB films is the other indirect method for observation of compositional heterogeneities. EDS in STEM is adopted as a direct method in CoZrNb thin films deposited with substrate bias and annealed after deposition, because the heterogeneous structure is enlarged enough to use electron beam in STEM on these films. Measurement of magnetostriction of magnetic films is also suggested as one of the methods observing the compositional heterogeneities in CoZrNb thin films. |