Influence of hydrogen on room-temperature grain growth of electrodeposited Cu films

Abstract

The influence of co-deposited hydrogen on the room-temperature grain growth of electrodeposited Cu films was investigated. The films were prepared from ethylenediamine (EDA)-complex and ethylenediaminetetraacetic acid (EDTA)-complex baths and examined with respect to hydrogen concentration, the initial microstructure, residual stress and impurities. Thermal desorption spectroscopy revealed that extremely high concentrations of hydrogen was contained in the Cu films deposited from both the EDA- and EDTA-complex baths. The room-temperature grain growth of these Cu films proceeded after deposition and concurrently with the gradual desorption of hydrogen. During the grain growth, the (111)-oriented texture remained almost unchanged but the tensile stress decreased. Compared with the Cu films electrodeposited from other types of baths, temporal changes in crystal orientation and residual stress varied in the different baths, however grain growth proceeded with a decrease in hydrogen as previous. These results indicate that the primary cause of room-temperature grain growth of electrodeposited Cu films is hydrogen-induced superabundant vacancies.