Design Guideline to Improve Thermal Management of 3D Package Using Cu-to-Cu Direct Bonding

Three-dimensional (3D) packaging technology is directly related to the increasing I/O number as stacking chips. This technology has the potential to produce integrated circuits with a much better combination of cost, functionality, performance and power consumption. However, stacked chips raise several thermal issues that need to be addressed and eliminated. In this study, a quantitative study of the conventional solder-based interconnection is conducted based on many different cases of thermal loading, using finite element analysis (FEA). This preliminary study clearly shows limitation of the solder-based interconnection in the thermal management perspective. Underfill for microbμmp acts as a barrier of heat transfer in the conventional 3D stacked chip packages. Therefore, as an alternative, Cu-to-Cu direct bonding (CuDB), which has a better thermal conductivity, is proposed. Its parametric study is performed under the same/different loading conditions and dimensions. This study helps to highlight the thermal behavior of 3D packages consisting of various interconnections. Finally, based on the results, we can propose qualitative design guidelines of 3D packaging depending on various environment and conditions.