Scaling of interconnect feature sizes changes the mass transport mechanisms that are responsible for electromigration failure of conductors. For deep submicron applications two of the most important issues related to electromigration are the dominant pathway for mass transport in a bamboo grain, and the influence of the Cu on the rate of drift of bamboo AlCu lines. This paper examines these issues, using the stripe drift technique to measure the drift velocity. We show that the dominant pathway for electromigration in bamboo grains is through the lattice at accelerated testing temperatures for conductor widths down to 0.6 &mgr;m. In Al-0.5&percent;Cu alloys, the drift velocity is unaffected by the presence of the Cu dopant, indicating that depletion of Cu atoms in solution does not affect the drift velocity in bamboo Al grains. ©1998 American Institute of Physics.