Impact of Residual Impurities on Annealing Properties of Vacancies in Electroplated Cu Studied Using Monoenergetic Positron Beams

Abstract

Positron annihilation was used to probe vacancies in Cu films deposited by Ta/SiO2/Si using electroplating and sputtering techniques. During room temperature grain growth (i.e., self-annealing) of the Cu films, two different types of vacancies (small vacancy clusters such as divacancies and large vacancy agglomerates) were introduced into grains; the formation of such defects was enhanced by residual impurities. For electroplated Cu, isochronal annealing experiments revealed further agglomeration of vacancies when annealing was done below 300 °C, and these agglomerates started to dissociate above 350 °C. The effect of impurities on the vacancy agglomerates disappeared in the defect recovery stage (≥350 °C).