晶背清洗工艺对焊盘结晶缺陷的影响研究

he pad crystal defect is a kind of cyrstal defect caused by the corrosion of the fluorine, which may lead to failure of the wire bonding. In this paper, combined with the existing theory and research on the formation mechanism of the pad crystal at home and abroad, this paper analyzes and probes into the process steps that may cause the crystal defect in wafer fabrication. Through verification experiment, we reproduce the pad crystal on the wafer with one backside cleaned wafer right above, which proves that the backside clean process after cover etch is one of the most important root cause of the induction of fluorine to the aluminum bond pad. By changing the contamination class of some steps in the far backend process flow, the occurrence rate of pad crystal defect can be reduced effectively by canceling the backside clean step.