In-situ observation study on nano constriction spacer NOL for CPPGMR by conductive AFM

This paper investigates in-situ characterization method for metallic path shapes and their distributions inside the nano-oxide layer (NOL) by using the conductive atomic force microscopy (AFM) and reports on the effect of the assist energy upon the formation of the metallic path inside Al-Cu NOL. Film stacks of Cu/Al are deposited on a thermally oxidized Si substrate by ECR ion beam sputtering. RHEED images reveal that further increasing the annealing temperature to more than 200°C, the disappearance of the clear rings from the Cu or the Al surfaces can be recognized due to the structural change by the alloying or segregation in both Al/Cu and Cu/Al bi-layer samples. Topographic images of the sample unoxidized with bias voltage of 0.5 V show round shape microstructures and there are both bright and dark areas in the electric current (conductive AFM) image where a bright one means apparently the shape of the metallic channels on the surface of the NOL. On the other hand, topographic images of samples annealed at 300°C before oxidation show a decrease in grain size and channel size.