Three-dimensional structuring of electrodeposited Cu-Co multilayer alloys

Scanning and transmission electron microscopy (TEM) were used to characteri ze the microstructure of electrodeposited multilayer Cu-Co alloys. Both col umnar alloys (where the Co is localized to the columns) and three-dimension al arrays (where the Co is present in regions less than 1 mum diam) were st udied. The Latter type was produced by successively electrodepositing a col umnar alloy layer between Cu spacer layers, resulting in a semiordered, thr ee-dimensional network of Co-rich regions in a principally Cu matrix. The c omposition gradient between the Co-rich regions and the Cu matrix was verif ied by electron energy loss spectroscopy and energy-dispersive spectroscopy using TEM. It was found that the size of the Co-rich regions was affected more by the overall alloy layer composition than by the deposition paramete rs. Under appropriate conditions, it was possible to reduce the individual alloy layer thickness to 25 run while maintaining chemical segregation betw een the Co-rich areas. Annealing at 250 degreesC and higher caused the Co-r ich regions to merge together. (C) 2001 The Electrochemical Society.