Effect of stress control layer (SCL) on via-stability in organic low-k/Cu dual damascene interconnects under thermal cycle stress

Stability of organic low-k/Cu dual damascene interconnect under thermal cycle stresses is investigated, concluding that the thermal stability is improved by introducing Stress Control Layer (SCL) between metal-level inter-layer dielectric (ILD) film and via-level ILD film. The mismatches of the coefficient of thermal expansion (CTE) and the Young´s modulus among the Cu, ILD and SCL films cause the stress voiding defects around the via-holes. In the case of CTE of SCL close to that of Cu, the via-stress opening is suppressed. When the modulus of SCL is closed to that of ILD, the voiding in the ILD around the via is suppressed. The selection of SCL material is a key part to improve the reliability of organic Low-k/Cu interconnect under severe thermal cycles.