Surface roughness reduction in nanocrystalline Cu thin films by electrical stressing treatment

摘要

Electromigration-induced surface morphological evolution of nanocrystalline Cu thin films is reported. When applying a high-density current (10~6 A/cm~2), the Cu films showed reduced surface roughness from 7.5 to 1.4 nm after electrical stressing at the temperature below 100 ℃. It is suggested that preferential surface diffusion on Cu(l11) planes leads to thinning of extruded grains in the electrically stressed Cu film, as evidenced by the weakening (111) texture of the Cu film after electrical stressing. The electrical stressing process shall help reduce roughness of Cu metallization after post thermal treatment.