In-SituMeasurements of Stress during Electrodeposition of Copper Nanofilms: Current Interruption Effects, Migration of Atoms and the Effect of Chloride Ions

Using a substrate curvature method, stress was monitored ui-situ in acidic CuSO₄ electrolytes with and without chloride as an additive. Chloride in the electrolyte considerably reduced the tensile stress. Chloride-free and chloride-containing electrolytes also showed very different behaviors after interruption of electrodeposition. In chloride-free electrolyte, the tensile steady-state stress observed during deposition changed to compressive stress on interruption of the deposition. However, in chloride-containing electrolyte, the stress became even more tensile on interruption of deposition. The lower tensile stress in the presence of chloride is explained using a model based on the grain boundary diffusivity of copper and possible mechanisms for the behavior on current interruption are discussed.