The Defect Formation and Reduction of 55NM Ultra-Low Power (55ULP) BEOL Process

In this paper, dark field inspection tool is implemented in the detection of three main type defects in 55nm Ultra-low Power (55ULP) back-end-of-line (BEOL) manufacturing: the tiny particle of top metal final deposition, seal ring bulge defect after UTM process, and wafer edge cluster tiny particle after TEON process deposition. More defect can be scanning in new detection condition, and defect mechanisms are deduced with scanning results. Experiments designed for CVD (chemical vapor deposition) optimization scheme demonstrates that thicker Film, prolonger purge time lead to a good residue defect performance, meanwhile both getting rid of gas H2 of top metal via etch amount work for seal ring bulge defect reduction, moreover, offshoring cone to a certain distance contributes to lower wafer edge cluster tiny particle count. Make a summary for future development of 55nm ultra-low power and look forward to the future.