A study of the electrical resistivity increase in narrow and thin copper interconnects

Progress of semiconductor devices requires further reduction of line width and film thickness in Cu interconnects. As the line width and film thickness approach the electron mean free path, the increase in electrical resistivity exceeds the value predicted from the theoretical equation. When the thickness of Cu interconnects was reduced, the surface scattering became dominant with resistivity increase, and thus the optimization of Cu. surface condition is important in order to keep resistivity low.