Shiguang Li, Lei Guo, Haifeng Zeng, Yiyun Ji, Yin Wang, Yanqing Xiao. Focus Control in Optical Lithography[J]. Laser & Optoelectronics Progress, 2022, 59(9): 0922016
- Laser & Optoelectronics Progress
- Vol. 59, Issue 9, 0922016 (2022)
Fig. 1. Illustration of Ry
Fig. 2. Probability distribution of the sum of non-normal distribution error (caused by Ry) and normal distribution error (stochastic error)
Fig. 3. Schematic diagram of the advanced lithographic architecture
Fig. 4. Focus control workflow of dual-stage lithographic system[10]
Fig. 5. DMD lithography system
Fig. 6. Work flow related to focus control in mask manufacturing process
Fig. 7. Illustration of wafer surface measurement with optical triangulation method
Fig. 8. Canon’s early focusing and leveling sensor[14]
Fig. 9. Another Canon’s focusing and leveling sensor[15]
Fig. 10. Detecting beams and optical spots on the wafer surface[15]
Fig. 11. Nikon’s focusing and leveling sensor[16]
Fig. 12. Light spot array produced through slits in Nikon’s focusing and leveling sensor[17]
Fig. 13. Nikon’s focusing and leveling sensor equipped with reflecting prism[18]
Fig. 14. Lithography of Nikon. (a) Illustration; (b) corresponding focusing and leveling sensor based on tilting interference
Fig. 15. ASML’s original focusing and leveling sensor[20]
Fig. 16. ASML’s improved focusing and leveling sensor[20]
Fig. 17. Primary focus system 100 (left): exposure lens 108, control sensors 104 and 106, upper surface of a wafer 112; calibration subsystem 200 (right): calibration sensor 208, secondary control sensors 204 and 206[22]
Fig. 18. Focus control system developed by tsmc[23]
Fig. 19. Focus control system exposes at different heights simultaneously[23]
Fig. 20. ASML’s focusing and leveling sensor based on barometer measurement[24]
Fig. 21. ASML’s focusing and leveling sensor based on pressure wave measurement[25]
Fig. 22. ASML’s focusing and leveling sensor with Goos-Hänchen shift eliminating function[26]
Fig. 23. Nikon’s focusing and leveling sensor with Goos-Hänchen shift compensation function[27]
Fig. 24. Basic principle of leveling and focusing measurement accuracy affected by IC structure. Inset: stacked structure of processed silicon wafer[28]
Fig. 25. Simulation of different lengths of faculae sliding on wafer's surface with trench[29]
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