The surface damage in titanium nitride associated with lateral sputtering by argon cluster ions

The surface smoothing of TiN coatings, deposited by CVD or PVD methods, by argon ion clusters comprising some 2000 atoms and carrying only a single positive charge has been confirmed. In addition, the present work has shown that there was no change in the mechanical condition, nanohardness or residual stress, of the PVD coatings. In contrast, the nanohardness in the near-surface region of the CVD TiN coating was increased but, remarkably, there was no concomitant increase in residual stress. A comparison was made with the established effects of ion implantation on the near-surface properties of TiN where a high compressive residual stress is developed if the ion energy lies beyond a threshold value. It was concluded that the vast majority of argon atoms from the clusters move sideways on impacting the sample surface, leading to the well-known lateral sputtering effects associated with the technology, and causing limited surface damage.