Published online by Cambridge University Press: 01 February 2011
This study aims at assessing the role played by the coefficient of thermal expansion (CTE) and elastic modulus of low-k dielectric, in affecting the stress and deformation fields in copper interconnects. Parametric finite element analyses are conducted, varying one parameter at a time, for gaining fundamental understanding of the effect of individual properties. The analyses are based on a three dimensional model containing two levels of metal lines connected by a via. It is found that both the high CTE and low modulus values of the polymer-based dielectric contribute to the evolution of stress/strain fields in the metal structure. The low-k CTE plays a more significant role. Within certain limits, decreasing the low-k CTE and/or increasing the low-k modulus can help alleviate the plastic deformation, and thus the propensity of damage initiation, in the metal. Reducing the low-k CTE will be a more efficient and safer approach.