Strength analysis of advanced node BEOL under CPI induced stresses

At nanoscale level, the strength of the BEOL is determined by two competing failure mechanisms: adhesive failure (delamination) at the different interfaces and cohesive failure within the Cu-vias or in the low-k material. Different approaches to model delamination by FEM are discussed an evaluated. Although the current techniques are useful for qualitative comparison, it is identified that the future challenge for quantitative reliability modeling lies in tackling fracture initiation and mode mixity. Next, it is examined how the risk for cohesive and adhesive failure evolves in function of the stiffness of the low-k. The potential of our approach is demonstrated by the simulation of different failure mechanisms in some comparative cases.