Application of EBSD Study of Cu-Sn IMCs in SAC305 and Sn0.7Cu Solder Joints to Determine the Suitability of Sn0.7Cu Solder as Alternative in Mitigating ILD Cracks/Delamination

Interlayer dielectric (ILD) cracking/delamination remains a concern in semiconductor devices, especially as silicon technology nodes continue to shrink aggressively. The combination of brittle extreme-low k (ELK) dielectrics and stiff copper pillars and lead-free tin-silver-copper solders (SAC305) can increase the risk of this occurrence. A solution to mitigate this risk is to use lower modulus Sn0.7Cu solder. However, this may favour the formation of brittle IMC in solder joints, compromising the overall reliability performance of devices. Thus, a comparison study of IMCs between SAC305 and Sn0.7Cu solder joints was done to determine the feasibility of Sn0.7Cu solder as an alternative to mitigate ILD crack/delamination risks. This paper describes the application of EBSD in solder joint IMC studies to determine the suitability of Sn0.7Cu solder as an alternative to SAC305 to mitigate ILD cracking /delamination. Overall, the results showed that there were no significant differences in IMC thickness and crystal orientation between SAC305 and Sn0.7Cu solder joints, confirming Sn0.7Cu solder as a viable alternative.