Atomic Force Microscopy (AFM) is a well-established metrology technique used in semiconductor at 65nm nodes and below. Measurement precision, and accuracy are foundational to the AFM including the added benefits of not being a direct, non-destructive technique that is not affected by feature material or shape. In this application, the AFM is used in an advanced scan mode to monitor the depth of yield killing divots that form at the interface between the STI and the active area. AFM is now routinely used as as in-line monitor for divot detection.
AFM process monitoring offers the significant advantage of saving valuable time and resources with early divot detection long before discovering failure it at standard electrical test