Co-deposition of Nano-Size SiC Particles in Micro-Via

Thermal mismatch problem in micro-via interconnection, arising from the difference of the coefficient of thermal expansion (CTE) between copper (Cu) pillar and silica (Si) substrate, becomes increasingly crucial. It may result to defects, cracks, and delaminations of the interconnect structure, and finally to device failure in service. This paper introduces an innovation method to decrease the CTE difference in the micro-via. Through a co-deposition approach, nano-size SiC particles with lower CTE were incorporated into the micro-via to form SiC/Cu nanocomposite with lower CTE than traditional Cu pillar. The effects of the particle size, and the current density on the particle volume percentage of the Cu/SiC nanocomposite in the micro-via have been investigated experimentally. Our results showed that as the current density increased, the percentage of SiC particle in the micro-via is increased gradually, reached a maximum and then to decrease. Particles with diameter 500 nm exhibits larger volume percentage in the micro-via than that particles with diameter of 50 nm, while the latter had more number of particles incorporated in the nanocomposite in the micro-via.