The Studies of Spontaneous Potential Oscillation in a Galvanostatic Copper Electrodeposition and the Crystallographic Textures Thereof

This study reports the influence of the current density and the electrode rotating speed on spontaneous potential oscillation and crystallographic textures of the electrodeposited copper. The potential only spontaneously oscillated in the range of -0.44V ~ -0.49V with respect to saturated mercury-mercurous sulfate electrode (SMSE). This result implies that the electrochemical reduction of copper ions at the metal/solution interface is affected by those organic additives, and the electrochemical oscillation reaction depends on a specific potential range, which may relate with the adsorbed chemical species. In addition, the waveform of the potential oscillation is adjustable by the electrode rotating speed and the current density, and it affects the crystal structure and the surface microstructure of the deposited copper. The plated copper layers were characterized by FIB, FE-SEM, and HR-TEM, and we found a layered structure with a series of parallel twinned boundaries. Furthermore, the layered structure only formed with the specific waveform of the potential oscillation. The spontaneous potential oscillations observed in the copper deposition are explained according to the electrochemical studies and the corresponding microstructure analyses.