To improve the speed of integrated circuits it is highly important to minimize the electrical resistivity of their interconnects. In recent years copper has replaced aluminum as the interconnect metal due to its lower resistivity. However, as the dimensions of the interconnects approach the mean free path of the electrons ( 40 nm for copper at room temperature), a substantial rise in resistivity occurs due to additional electron scatterings from grain boundaries and interfaces. This issue has been acknowledged by the ITRS (International Technology Roadmap for Semiconductors) as one of the...