镀钯铜线键合中FAB表面的钯覆盖  

Palladium Coverage on Free Air Balls of Palladium-Coated Copper Wires Bonding

作　　者：浦浩楠[1] 王家楫[1] 俞宏坤[1] 

机构地区：[1]复旦大学材料科学系,上海200433

出　　处：《半导体技术》2013年第8期623-628,共6页Semiconductor Technology

摘　　要：铜引线键合由于低廉的成本和优良的材料综合性能而受到越来越多的重视,而镀钯铜线较纯铜线的应用更为广泛。其中,自由空气球(FAB)上钯的覆盖情况是需要进行研究的问题之一。由于烧球工艺为瞬态过程,因此在形成FAB后其表面的钯可能会出现不均匀的分布,后续的塑封环节中低含量的钯区域就会遭受外界的侵蚀,这对焊点的可靠性会有不良的影响。基于此,针对线径20μm镀钯铜线FAB上的钯覆盖区域进行了探究,并采用定制化的化学腐蚀方案来显示FAB上钯膜较厚区域和较薄区域在形貌上的差异。此外还讨论了不同电子火焰熄灭(EFO)工艺参数样品的钯薄弱区形状参数,最后分析了影响FAB表面上钯薄弱区的主要工艺因素,得到了相关工艺参数参考值,对后续工艺的可靠性提升有一定的借鉴意义。Copper wire bonding attracts increasing attention due to its low cost and excellent material performance. However, palladium-coated copper wire has more extensive application. Pd coverage research on the free air ball （FAB） is an important aspect among all the issues on palladium- coated copper wires. Pd may have nonuniform distribution on the free air ball due to transient electronic flame-off （EFO） process. After the mold encapsulation, the lower Pd content area on the FAB may have risk to be subjected to corrosion and lead to failure, which would influence the reliability of the solder. The Pd coverage on the FAB of 20 μm palladium-coated copper wires was studied, then customized etching conditions for different Pd film thickness were adopted to show surface morphologies of etched FAB. Moreover, various Pd coverage parameters of different samples also were compared and estimated with EFO process parameters varied. At last the main process issues of Pd weak area on FAB were analyzed, and the process reference parameters were obtained. The Pd coverage analysis provides a reference for the parameters and reliability in the following processes.

关 键 词：封装 铜引线键合 镀钯铜线 钯覆盖 电子火焰熄灭(EFO) 自由空气球 (FAB) 

分 类 号：TN305.93[电子电信—物理电子学]