Research on the Root Cause of THB Failure of Large Size Package Chip to Improve Reliability

In this paper, the root cause and mechanism of short failure of large size packaged chip in THB (Temperature Humidity Bias Life Test) are analyzed. We find that the failure mechanism of short is due to the introduction of aluminum-containing foreign matter in the substrate processing process, which produces cracks and provides an effective path for Cu migration. Under the conditions of high temperature, high humidity and voltage bias of THB, the electromigration of Cu ions occurs between the copper hole and the copper plane, thus forming a bridge conduction. Meanwhile, our analysis identifies the source of the foreign matter. The risk of foreign matter introduction is reduced by process protection. The ability to detect defects is improved by adjusting the electrical measurement parameters. The spark voltage is tightened from 10V to 2V, which can effectively detect the micro-short and the near-short defect mode. Moreover, the effectiveness of the countermeasures is verified, and the reliability of the chip is obviously improved.