Surface morphology and stress in electrodeposited copper nanofilms

In-situ stress measurements and in-situ AFM imaging were employed to study stress evolution during the electrodeposition of copper nanofilms from acidic copper sulphate electrolyte, at overpotentials of 125-200 mV and to compare the observed stress and morphology changes with theoretical predictions. As the films grew, tensile stress initially increased, corresponding to grain coalescence as observed by AFM, and reached a plateau value when significant GB volume had occurred. The time evolution of stress was examined during interruption of deposition. Generally, when deposition was interrupted, tensile stress decreased as predicted by Chason's model¹³ for low mobility deposits. At all potentials, upon resuming deposition stress recovered to its pre-interrupted state. Stress increased with increasing overpotential as expected from theory. Cl- was found to directly reduce stress and resulted in a rougher surface than was observed without additives.