Electromigration drift velocity in Cu interconnects modeled with the levelset method

Electromigration (EM) drift velocity (DV) experiments in polycrystalline pu re Cu lines are simulated numerically with the level set method. The simula tion is based on a grain boundary (GB) grooving model, incorporating an ele ctric field. The model is distinguished by two key requirements imposed at the triple point where two surfaces and a GB meet: that of GB and surface f lux coupling (flux continuity), and that of permanent equilibrium between s urface and GB tensions. Surface diffusion exists only at the advancing cath ode edge, and is driven both by local curvature gradients and by the local field. Using independent, literature diffusivity values, the simulation yie lds both the DV prefactor and the EM activation energy in an Arrhenius-type expression. An excellent match is obtained with experimental DV values in the T range of 573-723 K. Some implications regarding the material transpor t mechanism are discussed. (C) 2000 American Institute of Physics. [S0003-6 951(00)01647-8].