An electroplating method for copper plane twin boundary manufacturing

• A method is proved to enhance the formation of twin boundaries in the Cu films.
• The low-current interlayer can trap higher-level carbon to limit Cu grain growth.
• Multi-plane twin boundary can be manufactured to improve electron migration.

A twin boundary is a special kind of grain boundary that plays an important role in the deformation process of nanocrystalline metals, as it may affect the migration of atoms and electrons in polycrystalline solids, resulting in different electrical and mechanical properties. In this study, plane twin structures were introduced into an electroplated copper film by an electroplating method that inserts an interlayer film with a very small current density (< 3 mA/cm2). It was found that the small-current interlayer formed a demarcation line for copper grain growth, and enhanced the twin boundaries by self-annealing at room temperature. Based on this, a method was developed to manufacture multi-plane twin boundaries to improve electron migration. Transmission electron microscopy, focused ion beam analysis, and secondary ion mass spectrometry were employed to examine this interesting phenomenon.