Detecting yield-limiting SiGe defects for 28nm ramping

For foundry fabs, detecting systematic yield-limiting (Ys) defects is one of the most critical tasks during the R&D and ramping stages of the product life cycle. The sooner systematic defects can be identified, the faster fixes can be implemented to achieve a robust process. This, in turn, leads to shorter time-to-market, increased competitiveness for the foundry, and the potential reward of better profitability. This paper describes one example of early identification of a systematic defect. Yield-limiting SiGe defects at 28nm node were successfully detected using a new wavelength band on a broadband brightfield patterned wafer inspector. In addition to enhanced capture of defects of interest (DOI), this new optics configuration also effectively suppressed nuisance defects. The improved inspection capability of the broadband brightfield inspector enabled early capture of the SiGe systematic defects, helping engineers accelerate the yield ramp and preventing yield loss.