Improvement of C2W Collective Bonding Reliability and UPH through Innovations in Machine, Materials and Methods

We report detailed observations for temperature deviation (dT) on stacked dice and temperature for satellite dice (Ts) on several base materials with different thermal resistances to inspire new concepts for innovative collective bonding under a Thermal-compression Bonding (TCB) process. We also developed an enhanced Non-conductive Film (NCF) and flip-chip bonder, in order to solve current problems facing collective bonding for the C2W process. Various improvement measures for machine, material and method are presented to address the dT, Ts and units per hour (UPH) improvement challenges. We conclude that, when the proposed improvements are implemented, C2W collective bonding with high reliability and high-speed over 20,000 UPH is possible. As a further investigation, this paper is focusing on the productivity bottleneck to improve UPH for the pre-bonding step on a 3D stacked IC process. Finally, we propose a new 4-head flip chip bonder to increase UPH for C2W collective bonding drastically.