A novel iso-thermal intermetallic compound insertion bonding approach to improve throughput for 3D die to wafer stacking

In this paper, we present a novel approach using preformed IMC layer to mechanically attach two dies at low temperatures and fast time followed by underfilling process. An isothermal bonding profile with a constant arm temperature was developed to save TCB bonding time. At optimized TCB bonding recipe, IMC insertion bonding offers a very short bonding time in the range of 2-5s for each die. The bonding interface temperature is around 150°C. The electrical test results and cross-section images show high stacking yield in the range of 95% and the void-free interface is obtained for a 20μm pitch microbump.