Electromigration failure of Al alloy metallization systems is one of the main concerns for integrated circuit reliability as feature sizes are reduced into the submicron regime. One of the most important aspects of electromigration failure is the current density dependence of the failure time. Many studies have been conducted for widths above 1 μm and the consensus of these studies indicates that a current density exponent, n=2, describes microstructure related failure of the metallization. There is very little data available, however, for feature sizes close to 0.5 μm, particularly for metallizations consisting of Al alloys clad by refractory layers. In this letter we investigate the current density dependence of microstructure related failure for narrow (0.6 μm) conductors with multilayer TiN refractory layers, and correlate this dependence with void formation by electromigration. We show that the current density dependence of microstructural failure in such narrow conductors differs significantly from that observed for widths above 1 μm. At 0.6 μm n as low as 1 is obtained compared with n=2 at 1.2 μm for microstructure‐related failure of long, multilayer stripes. The number of voids formed during accelerated testing and their average nucleation rate appear to be independent of the current density for 0.6 μm stripes, contrary to findings for wider stripes. It is suggested that growth of voids determines the failure kinetics of narrow stripes. © 1995 American Institute of Physics.