Effective use of customized AutoSAT templates in a foundry environment for better recipe set-up

Efficient defect detection and analysis is critical to the success of any fab. For a yield management group, it is essential to capture defects of interest and to eliminate defects that do not impact yield. In a foundry where multiple devices are manufactured, it is crucial to have an inspection strategy that is transferable to many devices. Such a strategy also needs to be effective in capturing the same defect types by process layer. This paper discusses the challenges involved in creating such a strategy and steps taken to successfully combat it through a collaboration between Chartered Silicon Partnership (CSP) and KLA-Tencor (K-T). A KLA-Tencor 2139 brightfield inspection tool was used for defect image capture. Segmented Auto Threshold (SAT), a tool available on the 2139, is used to eliminate nuisance defects during inspection. SAT is a powerful tool, but the inspection recipes can be complex. Another tool on the 2139, AutoSAT, may be used to facilitate creation of such sophisticated inspections. AutoSAT samples defects on the wafer and prompts the user to classify them as real, killer or nuisance. Once this is done, AutoSAT uses a predefined SAT template set to optimize the thresholds to suppress nuisance and enhance critical defect capture. This approach is particularly useful in a foundry environment where the yield management group is faced with a variety of devices, requiring many inspections.