VOID NUCLEATION IN PASSIVATED INTERCONNECT LINES - EFFECTS OF SITE GEOMETRIES, INTERFACES, AND INTERFACE FLAWS

Stress driven nucleation of voids in passivated aluminum interconnect lines is analyzed within the context of classical nucleation theory. A discussion of sources of tensile stress in such lines leads to an upp er limit of 2 GPa. Calculations suggest that even at this high stress, nucleation rates are far too low to account for observed rates of voi ding. Void formation at a circular defect at the line/passivation inte rface is then considered. In this case, a flaw on the order of nanomet ers in size may develop into a void under the imposed stress. These re sults strongly suggest that void nucleation in aluminum interconnect l ines can be controlled by eliminating defects in the line/passivation interface.