Effect of Hydrogen on Vacancy Formation in Sputtered Cu Films Studied by Positron Annihilation Spectroscopy

Abstract

As a part of the LSI interconnect fabrication process, a post-deposition high-pressure annealing process is proposed for embedding copper into trench structures. The embedding property of sputtered Cu films has been recognized to be improved by adding hydrogen to the sputtering argon gas. In this study, to elucidate the effect of hydrogen on vacancy formation in sputtered Cu films, normal argon-sputtered and argon–hydrogen-sputtered Cu films were evaluated by positron annihilation spectroscopy. As a result, monovacancies with a concentration of more than 10-4 were observed in the argon–hydrogen-sputtered Cu films, whereas only one positron lifetime component corresponding to the grain boundary was detected in the normal argon-sputtered Cu films. This result means monovacancies are stabilized by adding hydrogen to sputtering gas. In the annealing process, the stabilized monovacancies began clustering at around 300 °C, which indicates the dissociation of monovacancy-hydrogen bonds. The introduced monovacancies may promote creep deformation during high-pressure annealing.

Magnetron radio frequency sputtering growth of LaNi5 thin films and their hydrogen-sensitive properties at room temperature and ordinary pressure

“…In recent years, much attention has been focused on the intermetallic compound LaNi 5 , especially on its high hydrogen storage, as well as its rapid and reversible hydrogen-absorbing properties that are suitable for industrial applications [7][8][9][10]. However, research efforts have been directed on hydrogensensitive materials from LaNi 5 powder or bulk, instead of LaNi 5 thin films.…”