Resistivity of sub-30 nm copper lines

Resistivity data are presented for lines from 22 nm to 108 nm wide measured at room temperature and at 4.6 K. We also present numerical simulation data for 2-10 nm features. The experimental data are fit with standard Mayadas-Shatzkes and Fuchs-Sondheimer models which indicate that electron scattering from surfaces and from grains are the main contributors to resistivity for small features. The simulation data show that surface scattering dominates resistivity at smaller dimensions. This suggests that improvements in resistivity should focus on minimizing the impact of surfaces and grains, which has implications for interconnect material selection.