凸点下金属层湿法刻蚀与凸点底切的控制

介绍了电镀凸点封装工艺流程和其中有关金属层湿化学刻蚀的问题.通过槽式批量和单片机刻蚀相应的UBM(凸点下金属层)的均匀度、刻蚀速率和凸点底切的对比,结果显示单片湿法刻蚀机刻蚀均匀度小于5%且片与片之间刻蚀速率差异小于2%,以及凸点底切小于2μm.槽式刻蚀均匀度较差,一般会大于20%,同时同一批次片与片之间刻蚀速率差异也较大,实验显示超过10%,且刻蚀后凸点底切较深.因此采用单片机进行UBM金属刻蚀可以较好的控制刻蚀过程和提高产品的良率.

Wet UBM Etching and Bump Undercut Control

The process flow of electroplating bump and the issues of UBM wet etching were discussed. The etching uniformity of UBM layer and the bump undercut were compared by batch tool and single wafer tool. By single wafer etching tool, the etching uniformity is less than 5 % and the difference of etching rate is less than 2% among wafers, and the bump undercut is also less than 2 μm. However, by batch tool etching, the uniformity is more than 20% and the difference of etching rate is grater than 10% in the same lot of wafers, and the bump undercut is deeper than 7 μm. Thus, it will improve the final yield rate of etching UBM layers by single wafer tool.