Long-Term Reliability of Solder Joints in 3D ICs Under Near-Application Conditions

In this work, the long-term reliability of solder joints in 3D memory ICs (Integrated Circuits) was investigated. Three types of acceleration tests were carried out, where the temperature-time profiles were chosen to reflect near-operation conditions. For components after 500, 1000, and 1500 hours of testing, the formation and growth of intermetallic compounds (IMCs) in C4 bumps was inspected and analyzed using characterization techniques including scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD). Different IMC growth behaviors were observed among the three different test conditions and discussed. The different behaviors between C4 bumps and μ-bumps were also evaluated, which can be traced to differences in the solder volume and the IMC/solder ratio between these two structures.