T. C. Liu, H. W. Liu, M. L. Chang, K. T. Chiang, J. Lin, Integrated Service Technology Inc., Hsin-chu, Taiwan

Summary: In this paper, the harmful conventional methods in attempt removing the poly-Si sealing cap from MEMS device were demonstrated and described. They not only present the unacceptable result of decapsulation, but also bring about the concerned safety issue of using hot acid for over hours. A novel non-destructive technique has been successfully developed using KOH wet chemical etching with the following application of ex-situ hand sticking to deprocess the sealing cap from the MEMS accelerometer without disrupting the functionality of the underneath sensing parts to permit further accurate failure analysis. In summary, the innovation of this approach not only provides a quick and reliable way to remove the sealing cap from MEMS device within the short periods of 5 minutes, but also significantly improve the success rate and turnaround time for further failure root cause identification.