SPATIALLY-RESOLVED CONCENTRATION MEASUREMENTS DURING CATHODIC ALLOY DEPOSITION IN MICROSTRUCTURES

Local concentration distributions within microstructures, alloy compos ition, the effects of side reactions and the influence of convection o n electrodeposition in microstructures were measured. Since technicall y relevant microstructures have complex geometries, experiments involv ing locally resolved measurements using freely positionable microelect rodes are necessary. The SLCP method is based upon chronoamperometry a nd was used for simultaneous measurement of absolute concentration val ues of copper and nickel. In this way concentration profiles were meas ured as c(xy), c(x) and c(z). In a trench microstructure, concentratio n distribution was investigated as a function of the aspect ratio in u nstirred solution and under convectional influence. In direct comparis on to the conditions in the unstirred electrolyte, a notable intrusion of the flow is observed at aspect ratios less than or equal to 1. At a higher aspect ratio the concentration distribution is uniform. With higher aspect ratios leg 1.5) the effects of side reactions on the met al deposition increase. During Cu-Ni alloy deposition the formation of nickel oxide and nickel hydroxide layers can be detected. (C) 1997 Pu blished by Elsevier Science Ltd.