金丝球焊复合键合工艺可靠性研究

Study on the Reliability of Au Wire Ball Compound Bond

对芯片铝焊盘上不同重叠面积的金丝球焊复合键合的可靠性进行研究,并与非复合键合进行对比。结果表明,随着复合键合重叠面积的减少,键合拉力和界面生成的合金化合物面积均无明显变化,而剪切强度呈下降趋势。高温储存结果表明,复合键合拉力值满足国军标要求。复合键合有掉铝和弹坑缺陷隐患。经分析,原因是复合键合时施加的超声能量破坏了硅及金属化的结合态,在硅及金属化的结合界面上形成微裂纹。复合键合在高可靠电路中应进行键合参数优化并验证充分后使用。

The reliability of Au wire ball compound bond to aluminum pads with different overlapped areas, as well as non-compound ball bond, was comparatively investigated. The results demonstrated that the wire pull force and the intermetallic compounds coverage formed at the interface showed no obvious variation, while the shear strength reduced, along with the decrease of the compound bond overlapped area. The high temperature storage results showed that the wire pull force of compound bond met the GJB2438 reliability requirement. However, there was an increased tendency of lifting metallization and crater in the compound bond, in that the ultrasonic energy destroyed the connection between the silicon substrate and the metallization above it, and then forming microcrack at the interface. As a result, the compound bond parameters should be optimized and sufficiently verified before use, especially in the application of high reliable circuits.