DIrect observation of a current-confined-path nano-oxide layer structure by three-dimensional atom probe

Successful observation of current-confined-path (CCP) structures in the current-perpendicular-to-plane (CPP) film by the local electrode atom probe (LEAP) is reported. The CCP-CPP spin-valve film is composed of substrate/Ta/Ru/PtMn/CoFe/Ru/CoFe/CCP-nanooxide layer(NOL) spacer/CoFe/NiFe, where CCP-NOL spacer layer of AlCu-NOL is formed by ion-assisted oxidation. LEAP images show that field evaporation successfully progressed from the top protective cap to the bottom underlayer. In addition, the LEAP data clearly detects the CCP structure made by Cu in the Al/sub 2/O/sub 3/ matrix. The direct three-dimensional observation of the Cu-alumina CCP nano-structure by LEAP enables the derivation of the density of the metallic channels and the composition profile of the specific elements inside these metallic channels.