Scribe Line Self Reference Targets to enable Accurate and Robust After-Etch Overlay Metrology of Active layer

Direct in-device after etch overlay metrology on DRAM structures is highly demanded, because of a need to correct dense intra- and inter-die process variations. However, finding a robust and cost-effective metrology solution is challenging on active to active cut, due to low signal strength. The active cut litho and etch process is meant to cut the slanted multiple-patterned Si lines, creating iso...