Fig. 1. Evolution route of alignment technologies of ASML, Nikon, and Canon

Fig. 2. Schematic diagram of phase grating alignment (PGA) method^[39]

Fig. 3. Schematic diagram of TTL alignment technology^[41]

Fig. 4. Schematic diagram of XPA mark composed of four gratings^[43]

Fig. 5. Curve of normalized ±1 order diffraction light alignment signal strength versus slot depth in TTL alignment technology^［14］

Fig. 6. Schematic diagram of ATHENA^[45]

Fig. 7. Schematic diagram of diffraction stage separation in ATHENA^[40]

Fig. 8. Curve of normalized ±1-±7 order diffraction light alignment signal strength versus slot depth in ATHENA^[14,47]. (a) Normalized alignment signal strength corresponding to each wavelength; (b) maximum normalized alignment signal strength

Fig. 9. Schematic diagram of ATHENA mark^[43]

Fig. 10. Schematic diagram of SPM mark improvement^［3］. (a) Schematic diagram of SSPM-X mark (Image rotated by 90° is SSPM-Y mark); (b) schematic diagram of NSSM-X mark (Image rotated by 90° is NSSM-Y mark)

Fig. 11. Schematic diagram of SMASH^[39,53]

Fig. 12. Schematic diagram of interferometer module structure in SMASH^[53]

Fig. 13. Schematic diagram of SMASH mark^[3]

Fig. 14. Basis of D4C software evaluation and screening marks^[60-61]

Fig. 15. Flow chart of D4C software design marking^[57]

Fig. 16. Type of mark and segmented method^[61]. (a) Unsegmented mark; (b) scan direction segmented mark; (c) non-scan direction segmented mark; (d) scan direction and non-scan direction segmented marks; (e) inclined segmented mark

Fig. 17. Mark asymmetric deformation resulting in position error^[57]. (a) Schematic diagram of marking symmetry; (b) schematic diagram of marking asymmetry

Fig. 18. Schematic diagram of OCW method^[63]

Fig. 19. Simulation results of filtering effect of WAMM model mapping matrix M^[64]

Fig. 20. Schematic diagram of LSA. (a) Three-dimensional diagram^[23] ; (b) schematic diagram of X direction^[24]

Fig. 21. LSA mark^[24]. (a) Search mark-X; (b) search mark-Y; (c) EGA mark-X; (d) EGA mark-Y

Fig. 22. Schematic diagram of FIA^[22]

Fig. 23. FIA mark^[73]. (a) Search mark; (b) EGA mark

Fig. 24. Schematic diagram of LIA^[22]

Fig. 25. Schematic diagram of TTL alignment technology^[31]

Fig. 26. Schematic diagram of TTL alignment mark^[31]

Fig. 27. Schematic diagram of OAL for single stage lithography machine^[34]

Fig. 28. OAL alignment mark. (a) Cross alignment mark^[77]; (b) long strip alignment mark^[78]

Fig. 29. Multi grating alignment system^[79]. (a) Structure diagram of alignment system; (b) structure diagram of alignment mark

Fig. 30. Reflection-style alignment optical path based on Moiré fringes^[16]

Fig. 31. Four-quadrant gratings Moiré fringe alignment mark^[81]. (a) Silicon wafer grating mark; (b) mask grating mark

Fig. 32. Simultaneous multi-channel absolute position alignment by multi-order grating interferometry^[89]

Fig. 33. Principle diagram of self-coherence Moiré fringe alignment technology^[21]

Fig. 34. Comparison diagram of diffraction efficiency of each mark^[92]. (a) AH11; (b) AH53; (c) IME3; (d) IME5