Boron diffusion in MgO was investigated in annealed film stacks of sputtered

CoFeB|MgO using transmission electron microscopy and parallel electron energy

loss spectroscopy. The analyses showed significant B movement when the films

were annealed, with the formation of BOx complexes. Characteristic diffusion

lengths were estimated in films annealed at the commonly used range of 300 to

400C for the fabrication of magnetic tunnel junctions. An activation energy of

1.3eV was extracted from these data that represent B diffusion in MgO through

vacancies and defect states mediated by the formation of BOx complexes.

Study of Boron Diffusion in MgO in CoFeB|MgO Film Stacks Using Parallel

Electron Energy Loss Spectroscopy. S.S.Mukherjee, D.MacMahon, F.Bai, C.L.Lee,

S.K.Kurinec: Applied Physics Letters, 2009, 94[8], 082110