Comprehensive Study of Multi-Die Stacking with CuSnAg bumps in two step bonding process

2.5D/3D integration is being adopted in the industry to address the need for faster, better functioning capabilities [1], [2], and [3]. 3D integration deployed the stacking of device on top of each other to reduce the interconnect's length and thus improve the electrical performance. Cost is still the major concern in 3D integration. Assembly cost is one of the major component of the package. The assembly cost can be reduce either by selecting the low cost material or having high throughput process with high yield. Several researchers had demonstrated high throughput either adopting collective die to wafer bonding, and 2 step bonding processes that ensured formation of solder interconnects at the end of the process [4], [5] and [6]. In this work, 2 step bonding process for multi die stacking utilizing local thermal compression bonding (tacking) and subsequent air-pressure gang bonding is adopted. The developed multi-die stacking module had demonstrated its reliability performance through un-bias highly accelerated stress test (uHAST) at 130°C / 85% relative humidity for 96hr and Temperature Cycling (TC) test at -40 °C/+ 125°C for 1000 cycles.