微影製程是不斷發展的半導體產業中非常重要技術之一，這項技術利用光學投影將線路結構曝光於晶圓上，製造出微米甚至是奈米等級尺寸之電路。相對於傳統的微影製程，數位微影製程不再需要使用光罩，而是透過各種光學元件如數位微反射鏡等，直接將線路影像投射至晶圓上。這樣的製程做法既可降低成本，也更容易進行客製化的製程需求。而本論文針對數位微影製程展開研究，使用了台科大實驗室之中自行搭建的數位微影曝光機台，進行了深入探討。首先是開發了一套針對數位三維微影的模型，透過光學模擬實際曝光條件，成功縮短了大量重複曝光與量測的時間。同時基於蒙地卡羅的演算法，針對每個微反射鏡獨立規劃落點能量。這項方法使用14-16μm大小的光點，能夠在曝光最小特徵尺寸為4μm的光阻圖案時，取得高達95%以上的誤差改善率。這不僅提升了製程效率，也提供了更高的製程精準度。並基於此優化落點位置上進行三維的側壁角製程規劃，達成在指定的區域內包含30∘、45∘、60∘角之側壁角特徵，並利用平台精度進行小範圍的移動曝光，達成光阻潛像的平滑化，最後引入了一種原位量測拼接旋轉畸變校正的演算法，使得在修正光學潛像拼接產生的接圖誤差時，僅需透過平台上的監控相機，而不必依賴計算光阻上的圖形誤差偏移來推測旋轉角度。

Photolithography is an essential technology within the semiconductor industry. This technique utilizes optical projection to expose circuit patterns onto a wafer, enabling the manufacturing of circuits with dimensions in micrometers. In contrast with past, digital lithography processes eliminate the need for photomasks and instead employ optical components such as Digital Micromirror Devices (DMDs) to project circuit images directly onto the wafer. This approach can reduces costs and facilitates customization to meet specific process requirements. This paper focuses on the research of digital lithography, utilizing a digital exposure system constructed in-house at the National Taiwan University. Firstly, a model tailored for three-dimensional digital lithography was developed, employing optical simulations to significantly reduce the time spent on repetitive exposure and measurements. Additionally, a Monte Carlo-based algorithm was implemented, independently planning the energy distribution for each micro mirror. This method, utilizing 14-16μm-sized spots, achieved an improvement rate exceeding 95% in errors when exposing resist patterns with a minimum feature size of 4μm. This optimization extended to the planning of three-dimensional sidewall angles based on the improved drop positions. Furthermore, within specified regions, including sidewall angles of 30°, 45°, and 60°, small-scale movement exposure utilizing platform precision was employed to achieve smooth resist sidewall images. Finally, an algorithm for in-situ measurement stitching and rotation distortion correction was introduced. This method enables the correction of alignment errors in stitched optical images using only the monitoring camera on the platform, eliminating the need to infer rotational angles based on computed pattern deviation on the resist.

[1]Fang, Yuanxuan, and Yunfei He. “Resolution technology of lithography machine.” Journal of Physics: Conference Series. Vol. 2221. No. 1. IOP Publishing, 2022.
[2]M. Tu et al., “Direct X-ray and electron-beam lithography of halogenated zeolitic imidazolate frameworks,” Nature Materials, vol. 20, no. 1, pp. 93-99, 2021.
[3]Rosales-Guzmán, Carmelo, et al. “Polarisation-insensitive generation of complex vector modes from a digital micromirror device.” Scientific Reports 10.1, 2020.
[4]Yang, Jiamiao, et al. “Anti-scattering light focusing by fast wavefront shaping based on multi-pixel encoded digital-micromirror device.” Light: Science & Applications 10.1, 2021.
[5]Y. Watanabe et al., “Technology development progress of digital scanner,” in Optical and EUV Nanolithography XXXV, SPIE, vol. 12051: pp. 44-5,2022.
[6]I. Servin et al., “Process development of a maskless N40 via level for security application with multi-beam lithography,” in Novel Patterning Technologies 2018, SPIE,vol. 10584: pp. 198-208. 2018.
[7]Y. Watanabe et al., “Development of deep ultraviolet optical maskless exposure tool for advanced lithography,” Journal of Micro/Nanopatterning, Materials, and Metrology, vol. 22, no. 4, pp. 041403-041403, 2023.
[8]Grineviciute, Lina, et al. “Nanostructured multilayer coatings for spatial filtering.” Advanced optical materials 9.9: 2001730, (2021).
[9]Han, Manhee, et al. “3D microfabrication with inclined/rotated UV lithography.” Sensors and Actuators A: Physical 111.1: 14-20, 2004.
[10]Sato, Hironobu, et al. “In-channel 3-D micromesh structures using maskless multi-angle exposures and their microfilter application.” Sensors and Actuators A: Physical 111.1: 87-92, 2004.
[11]Yoon, Y-K., J-H. Park, and Mark G. Allen. “Multidirectional UV lithography for complex 3-D MEMS structures.” Journal of microelectromechanical systems 15.5: 1121-1130, 2006.
[12]Zhang, Naibo, et al. “Fabrication of Polymer@ Metal Core–Shell±45° Polarization Diversity Dipoles by Mussel-Inspired Surface Chemistry on 3-D Printed Objects.” IEEE Transactions on Components, Packaging and Manufacturing Technology 11.6: 892-898, 2021.
[13]Wang, Jirui, Zhiyang Li, and Zhiyong Gu. “A comprehensive review of template-synthesized multi-component nanowires: From interfacial design to sensing and actuation applications.” Sensors and Actuators Reports 3: 100029, 2021.
[14]Chung, Junwei, and Wensyang Hsu. “Fabrication of a polymer-based torsional vertical comb drive using a double-side partial exposure method.” Journal of Micromechanics and Microengineering 18.3: 035014, 2008.
[15]Otroshchenko, A. A., and I. Yu Makarikhin. “Laser 3D lithography, applications.” Вестник Пермского университета. Серия: Физика 2 (36), 2017.
[16]Z. M. Zhang, Y. Q. Gao, N. N. Luo, K. L. Zhong, and Z. H. Liu, “Multi-direction digital moving mask method for fabricating continuous microstructures,” Opt. Appl. 61(1), 79–99, 2015.
[17]R. Yang, S. A. Soper, and W. J. Wang, “Microfabrication of pre-aligned fiber bundle couplers using ultraviolet lithography of SU-8,” Sens. Actuators, A 127(1), 123–130, 2006.
[18]C. J. Ke, X. J. Yi, Z. M. Xu, and J. J. Lai, “Monolithic integration technology between microlens arrays and infrared charge coupled devices,” Opt. Laser Technol. 37(3), 239–243, 2005
[19]C. Q. Yi, C. W. Li, S. L. Ji, and M. S. Yang, “Microfluidics technology for manipulation and analysis of biological cells,” Anal. Chim. Acta 560(1-2), 1–23, 2006
[20]X. Zhang, X. N. Jiang, and C. Sun, “Micro-stereolithography of polymeric and ceramic microstructures,” Sens. Actuators, A 77(2), 149–156, 1999
[21]C. Sun and X. Zhang, “The influences of the material properties on ceramic micro-stereolithography,” Sens. Actuators, A 101(3), 364–370, 2002.
[22]M. A. Verschuuren, M. W. Knight, M. Megens, and A. Polman, “Nanoscale spatial limitations of large-area substrate conformal imprint lithography,” Nanotechnology 30(34), 345301, 2019.
[23]H. Schift, “Nanoimprint lithography: an old story in modern times? A review,” J. Vac. Sci. Technol. B 26(2), 458–480, 2008.
[24]M. A. Verschuuren, M. Megens, Y. F. Ni, H. V. Sprang, and A. Polman, “Large area nanoimprint by substrate conformal imprint lithography (SCIL),” Adv. Opt. Technol. 6(3-4), 243–264, 2017.
[25]Choi, Jae‐Won, et al. “Cure depth control for complex 3D microstructure fabrication in dynamic mask projection microstereolithography.” Rapid Prototyping Journal 15.1, 2009.
[26]Åstrand, M., Frisk, T., Ohlin, H., and Vogt, U., “Understanding dose correction for high-resolution 50 kv electron-beam lithography on thick resist layers,” Micro and Nano Engineering 16, 100141, 2022.
[27]M. Habets, J. Scholten, S. Weiland, and W. Coene, “Multi-mirror adaptive optics for control of thermally induced aberrations in extreme ultraviolet lithography,” in Extreme Ultraviolet (EUV) Lithography VII, SPIE,vol. 9776: SPIE, pp. 662-673, 2016.
[28]D. W. Kang, M. Kang, and J. W. Hahn, “Keystone error analysis of projection optics in a maskless lithography system,” International Journal of Precision Engineering and Manufacturing, vol. 16, pp. 373-378, 2015.
[29]S. Zhou, Z. Lu, Q. Yuan, G. Wu, C. Liu, and H. Liu, “Measurement and compensation of a stitching error in a DMD-based step-stitching photolithography system,” Applied Optics, vol. 60, no. 29, pp. 9074-9081, 2021.
[30]Y.-S. Syu, Y.-B. Huang, M.-Z. Jiang, C.-Y. Wu, and Y.-C. Lee, “Maskless lithography for large area patterning of three-dimensional microstructures with application on a light guiding plate,” Optics Express, vol. 31, no. 8, pp. 12232-12248, 2023.
[31]Sugioka, Koji, et al. “Femtosecond laser 3D micromachining: a powerful tool for the fabrication of microfluidic, optofluidic, and electrofluidic devices based on glass.” Lab on a Chip 14.18, 2014
[32]S. Turner and F. Cerrina, “Optimization of aerial image quality,” Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, vol. 11, no. 6, pp. 2446-2451, 1993.
[33]E. van Setten et al., “Edge placement error control and Mask3D effects in High-NA anamorphic EUV lithography,” in International Conference on Extreme Ultraviolet Lithography 2017, 2017, vol. 10450: SPIE, pp. 144-155.
[34]P. Gupta, “What is process window?,” ACM SIGDA Newsletter, vol. 40, no. 8, pp. 1-1, 2010.
[35]S. Okazaki, “Resolution limits of optical lithography,” Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, vol. 9, no. 6, pp. 2829-2833, 1991.
[36]Burov, Anatoly, Alessandro Vaglio Pret, and Roel Gronheid. "Depth of focus in high-NA EUV lithography: a simulation study." Photomask Technology 2022. Vol. 12293. SPIE, 2022.
[37]S. L. Norman and M. P. Singh, “Spectral Sensitivity and Linearity of Shipley AZ-1350J Photoresist,” Appl. Opt. 14, 818-820, 1975
[38]Hirai, Yoshikazu, et al. “A three-dimensional microstructuring technique exploiting the positive photoresist property.” Journal of Micromechanics and Microengineering 20.6: 065005, 2010.
[39]Loechel, Bernd. “Thick-layer resists for surface micromachining.” Journal of Micromechanics and Microengineering 10.2: 108, 2000.
[40]X. Ma et al., “Experimental study of numerical optimization for 3-D microstructuring using DMD-based grayscale lithography,” Journal of Microelectromechanical Systems, vol. 24, no. 6, pp. 1856-1867, 2015.
[41]Silver, Richard M., et al. “Comparison of edge detection methods using a prototype overlay calibration artifact.” Metrology, Inspection, and Process Control for Microlithography XV. Vol. 4344. SPIE, 2001.
[42]Bauer, W. F. “The monte carlo method.” Journal of the Society for Industrial and Applied Mathematics 6.4: 438-451, 1958.
[43]R. Y. Rubinstein and D. P. Kroese, “Simulation and the Monte Carlo method.” John Wiley & Sons, 2016.
[44]Dunn, William L., and J. Kenneth Shultis. “Exploring monte carlo methods.” Elsevier, 2022.
[45]Rosenblatt, Murray. “A central limit theorem and a strong mixing condition.” Proceedings of the national Academy of Sciences 42.1: 43-47, 1956.
[46]Jones, Galin L., and Qian Qin. “Markov chain Monte Carlo in practice.” Annual Review of Statistics and Its Application 9: 557-578, 2022.