Delamination-induced dielectric breakdown in Cu/low-k interconnects

Delamination at an interface with the weakest adhesion strength, which is found to be between the SiC(N) capping layer and the SiOCH low-k dielectric, is a potential failure mechanism contributing to time-dependent dielectric breakdown (TDDB) reliability. Bond breaking at that interface is believed to be driven by a field-enhanced thermal process and catalyzed by leakage current through the capping layer based on physical analyses and TDDB measurements. Delamination is found to be easier in terminated tips and comers than in parallel comb lines due to the layout orientation of the Cu lines. Moreover, TDDB activation energy E_a can be an indicator of the ease of delamination, whereby a lower E_a corresponds to an easier delamination.