Blech Effect in Copper Interconnects, Its Applications and Design Considerations

Electromigration results are compared for Cu interconnects with either SiO2 or low-k organic spin-on layer as the dielectrics, where its dependence on the dielectric material is insignificant over the range of experimental conditions. Considering the difference in mechanical modulus between the two dielectric materials, the Blech effect in electromigration is likely to be limited by the delamination between the dielectrics and capping layer. Finally, design considerations based on finite element modeling will be discussed, including the benefit in allowed current density from the Blech effect, particularly for high temperature applications.