Reliability Issues in Cu/low-k Structures Regarding the Initiation of Stress-Voiding or Crack Failure

Continuous down scaling of the interconnect dimensions led to the introduction of copper and low-k dielectric materials. The use of such materials is challenging in the field of mechanical reliability, such as stress-induced voiding in copper interconnects and cracking of low-k dielectrics. Up to now these two failure modes were investigated separately. However, recent experimental observations tend to demonstrate the possibility of a complex interaction of both failure modes, one overwhelming or enhancing the other. In this paper a comparison of the risk of void or crack occurrence is made by the mean of finite element modelling. Further, the interaction between these two failure modes (voiding and cracking) is also studied