Using In-Device Metrology (IDM), we show results of non-destructive overlay measurements on 3D-NAND memory holes. Once the overlay signal has been determined, the remaining asymmetry information in the measurement can be used to characterize tilt phenomena densely through the memory array.
Using hyper-dense in-device measurements show the overlay effects of intra-die stress. A new lithography scanner model is used to correct specifically for such intra-die overlay fingerprints.