Fig. 1. The selected alignment mark

Fig. 2. Alignment process of overlay

Fig. 3. Optical picture of the target pattern under the lithographic microscope system

Fig. 4. Photos of the first alignment

Fig. 5. The results of the first alignment exposure and development

Fig. 6. Photos of the second alignment

Fig. 7. Photos of the second alignment calibration

Fig. 8. The results of the second alignment calibration exposure

Fig. 9. Optical images after using the calibration scheme