Finite element simulation of thermomechanical stress evolution in Cu/low-k interconnects during manufacturing and subsequent thermal cycling

The integration of low-k interlayer dielectrics in interconnects is associated with an increase in mechanical reliability risks. Thermomechanical stresses must be evaluated to understand the behavior of interconnects. As manufacturing processes can introduce large stresses, a sequential process modeling technique is developed in this study. The constituent materials of the interconnects are described by a single elasto-plastic constitutive equation developed from substrate curvature measurements. Stresses in Cu/low-k lines are also evaluated. A good correlation between finite element modeling and curvature measurements is obtained.