High-K Bubble Defect Researches in Stack-BSI Process Product

Back-side deep trench isolation (B-DTI) with high-k film passivation is widely used in back-side illuminated (BSI) CMOS image sensor (CIS) technologies. Since the high-k film is weakly adhered to silicon or ultrathin silicon-oxidation, high-k bubble (HKBB) defects is a challenge to enlarge the wafer back-side processing window. It is proved, by deep study in HKBB defects, film stress and localized pattern finetune could enhance the process health. So, based on this phenomenon, experiments by stress optimization and DTI dummy design insertion is excused. At last, the result is confirmed, and final solution is discussed in the article.