Interdiffusion, stress, and microstructure evolution during annealing in Co/Cu/Co trilayers

Abstract

In order to find interdiffusion and microstructural changes on sputtered 90 nm Co/180 nm Cu/90 nm Co trilayers during annealing, the evolution of the stress and electrical resistance was studied in situ during temperature ramps and isothermal annealing as well as concentration-depth profiles, the grain morphology, and the phase and texture formation were investigated after heat treatment at various temperatures. Up to 450°C, no distinct lattice interdiffusion was observed. Grain-boundary diffusion of Cu through the Co top layer to the surface as well as a distinct growth of Cu grains into the Co top layer start to occur at about 450°C. The conclusions corroborate findings on Cu/Co nanoscale multilayers, which show a deterioration of the giant magnetoresistance effect at high temperatures due to similar microscopic mechanisms. © 2002 American Institute of Physics.