Thermomigration-induced void formation in Cu-interconnects - Assessment of main physical parameters

Using a dedicated test structure, the main physical parameters of void formation due to thermomigration (TM) were assessed. Based on physical and electrical void-analyses, we experimentally determined the time to void nucleation and estimated the heat of transport parameter
$Q^{\ast}= 0.21$
eV for Cu interconnects with CD~1µm, Our studies show that TM has a 6x higher contribution to metal flux compared to the initial stress migration (SM) induced by the coefficient of thermal expansion (CTE) mismatch.