Growth kinetics of IMCs in Cu-Sn intermetallic joints during isothermal soldering process

Following the continually increasing demand for high-density interconnection and multilayer packaging for the chips, the bump size is also decreasing significantly and tend to be the full IMCs interconnection right now. This work in the paper presents the systematic study on the characterization of full IMCs interconnection. The full Cu-Sn IMCs interconnection was fabricated using TLP (transient liquid phase) soldering method, which enables the possibility to systematically study the growth kinetics of Cu₃Sn in the full IMCs joints. The results illustrated that with the dwell time increasing, the microstructure of the IMCs joints gradually transformed from Cu₆Sn₅ into Cu₃Sn phase, and finally formed the Cu₃Sn IMC joint. The growth factor of Cu₃Sn is calculated to be around 0.29~0.48 in Cu-Cu₆Sn₅ diffusion couple, and the effect of types of substrates to form the joints is significant until 290°C. The amount of Kirkendall voids present linear relationship with dwell time, and to be affected by the thickness of Cu₃Sn and temperature.