Ong Jia-Juen, Tran Dinh-Phuc, Lan Man-Chi, Shie Kai-Cheng, Hsu Po-Ning, Tsou Nien-Ti, Chen Chih
Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan.
Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan.
Sci Rep. 2022 Jul 30;12(1):13116. doi: 10.1038/s41598-022-16957-y.
Cu-Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, cracks may form and propagate along the bonding interfaces during fatigue tests. In this study, Cu-Cu joints were fabricated at 300 °C by bonding 〈111〉-oriented nanotwinned Cu microbumps with 30 μm in diameter. After temperature cycling tests (TCTs) for 1000 cycles, cracks were observed to propagate along the original bonding interface. However, with additional 300 °C-1 h annealing, recrystallization and grain growth took place in the joints and thus the bonding interfaces were eliminated. The fatigue resistance of the Cu-Cu joints is enhanced significantly. Failure analysis shows that cracks propagation was retarded in the Cu joints without the original bonding interface, and the electrical resistance of the joints did not increase even after 1000 cycles of TCT. Finite element analysis was carried to simulate the stress distribution during the TCTs. The results can be correlated to the failure mechanism observed by experimental failure analysis.
铜-铜接头已被用于高端设备的超高密度封装。然而，在疲劳测试过程中，裂纹可能会在键合界面处形成并扩展。在本研究中，通过将直径为30μm的〈111〉取向纳米孪晶铜微凸点在300°C下键合来制备铜-铜接头。经过1000次循环的温度循环测试（TCT）后，观察到裂纹沿原始键合界面扩展。然而，经过额外的300°C-1小时退火后，接头中发生了再结晶和晶粒长大，从而消除了键合界面。铜-铜接头的抗疲劳性能显著提高。失效分析表明，在没有原始键合界面的铜接头中，裂纹扩展受到阻碍，即使经过1000次TCT循环，接头的电阻也没有增加。进行了有限元分析以模拟TCT过程中的应力分布。结果可以与实验失效分析中观察到的失效机制相关联。
