本論文設計一個一維電磁式驅動微機電掃描鏡系統，同時以N-well與多晶矽材料進行壓阻式感測，以進行閉迴路控制。壓阻阻值變化轉變的電訊號可進行鎖相迴路(PLL)以及自動增益控制(AGC)，使掃描結構能夠穩定的操作在一定頻率、轉角之下，形成穩定系統。
本研究使用台積電0.35μm 2P4M CMOS製程，實際晶片大小為10mm × 7mm，搭配專屬的後製程，來實現CMOS MEMS掃描鏡系統，達成製程的高整合度。經量測後，該晶片操作的頻率為1266 Hz。最大輸入4.81mApp時，位於共振頻率的光學轉角可到達32.55度。轉角感測的部分，45度擺放的N-well的感測度相較多晶矽電阻有更佳的感測度，其感測度可達到16.1027 mVpp/deg。閉迴路系統的PI控制器能使穩定控制感測輸出振幅，使振幅偏移約為1.512ppb/min。此微掃描鏡規格已達到光雷達中多數裝置的基本要求，並且可以藉由內部的壓阻來進行回授控制。

A 1D electromagnetic driven MEMS scanning mirror with integrated piezoresistive sensing is presented in this thesis. N-well and polysilicon are the piezoresistive materials which can sense the scanning angle. Changing of resistivity can convert to be the sensing signal, and the sensing signal can be used for amplitude and frequency control to stabilize the whole system. Closed-loop control of amplitude and frequency can be implemented by phase-lock loop (PLL) with automated gain control (AGC).
In this study, chip is implemented by TSMC 0.35μm 2P4M CMOS process, with a series of MEMS post-fabrication process, and total chip area is 10mm × 7mm. The resonant frequency is 1266Hz, and the maximum optical scanning angle is 32.55° in 4.81mApp driving current. Sensitivity of 45°-placed N-well piezoresistor is 16.1027 mVpp/deg, which is much higher than the sensitivity of polysilicon. Closed-loop control is implemented by both PI controller and PLL within a lock-in amplifier. PI controller can substantially enhance the stability of the scanning mirror system, and sensing amplitude drifting is as small as 1.512ppb/min. The measurement result shows the compatibility of most LiDAR applications, and the significant improvement of stability by PI controller.

[1] J. W. Judy, "Microelectromechanical systems (MEMS): fabrication, design and applications," Smart materials and Structures, vol. 10, no. 6, p. 1115, 2001.
[2] J. M. Bustillo, R. T. Howe, and R. S. Muller, "Surface micromachining for microelectromechanical systems," Proceedings of the IEEE, vol. 86, no. 8, pp. 1552-1574, 1998.
[3] P. Wang, "Research on comparison of LiDAR and camera in autonomous driving," Journal of Physics: Conference Series, vol. 2093, no. 1, p. 012032, 2021/11/01 2021.
[4] A. Gelbart, B. C. Redman, R. S. Light, C. A. Schwartzlow, and A. J. Griffis, "Flash lidar based on multiple-slit streak tube imaging lidar," in Laser Radar Technology and Applications VII, 2002, vol. 4723: SPIE, pp. 9-18.
[5] S. W. Hutchings et al., "A reconfigurable 3-D-stacked SPAD imager with in-pixel histogramming for flash LIDAR or high-speed time-of-flight imaging," IEEE Journal of Solid-State Circuits, vol. 54, no. 11, pp. 2947-2956, 2019.
[6] C. V. Poulton et al., "Long-range LiDAR and free-space data communication with high-performance optical phased arrays," IEEE Journal of Selected Topics in Quantum Electronics, vol. 25, no. 5, pp. 1-8, 2019.
[7] J. K. Doylend, M. Heck, J. T. Bovington, J. D. Peters, L. Coldren, and J. Bowers, "Two-dimensional free-space beam steering with an optical phased array on silicon-on-insulator," Optics express, vol. 19, no. 22, pp. 21595-21604, 2011.
[8] U. Hofmann, F. Senger, F. Soerensen, V. Stenchly, B. Jensen, and J. Janes, "Biaxial resonant 7mm-MEMS mirror for automotive LIDAR application," in 2012 International Conference on optical MEMS and nanophotonics, 2012: IEEE, pp. 150-151.
[9] L. Ye, G. Zhang, and Z. You, "Large-aperture kHz operating frequency Ti-alloy based optical micro scanning mirror for LiDAR application," Micromachines, vol. 8, no. 4, p. 120, 2017.
[10] L. Ye, G. Zhang, Z. You, and C. Zhang, "A 2D resonant MEMS scanner with an ultra-compact wedge-like multiplied angle amplification for miniature LIDAR application," in 2016 IEEE SENSORS, 30 Oct.-3 Nov. 2016 2016, pp. 1-3.
[11] R. Halterman and M. Bruch, Velodyne HDL-64E lidar for unmanned surface vehicle obstacle detection (SPIE Defense, Security, and Sensing). SPIE, 2010.
[12] X. Zhang, S. J. Koppal, R. Zhang, L. Zhou, E. Butler, and H. Xie, "Wide-angle structured light with a scanning MEMS mirror in liquid," Optics Express, vol. 24, no. 4, pp. 3479-3487, 2016/02/22 2016.
[13] K. E. Petersen, "Silicon torsional scanning mirror," IBM Journal of Research and Development, vol. 24, no. 5, pp. 631-637, 1980.
[14] S. T. Holmström, U. Baran, and H. Urey, "MEMS laser scanners: a review," Journal of Microelectromechanical Systems, vol. 23, no. 2, pp. 259-275, 2014.
[15] P. R. Patterson, D. Hah, M. Fujino, W. Piyawattanametha, and M. C. Wu, "Scanning micromirrors: an overview," Optomechatronic Micro/Nano Components, Devices, and Systems, vol. 5604, pp. 195-207, 2004.
[16] L. Fan and M. Wu, "Two-dimensional optical scanner with large angular rotation realized by self-assembled micro-elevator," in 1998 IEEE/LEOS Summer Topical Meeting. Digest. Broadband Optical Networks and Technologies: An Emerging Reality. Optical MEMS. Smart Pixels. Organic Optics and Optoelectronics (Cat. No. 98TH8369), 1998: IEEE, pp. II/107-II/108.
[17] W. C. Tang, T.-C. H. Nguyen, M. W. Judy, and R. T. Howe, "Electrostatic-comb drive of lateral polysilicon resonators," Sensors and Actuators A: Physical, vol. 21, no. 1, pp. 328-331, 1990/02/01/ 1990.
[18] A. Selvakumar and K. Najafi, "Vertical comb array microactuators," Journal of microelectromechanical systems, vol. 12, no. 4, pp. 440-449, 2003.
[19] R. A. Conant, J. T. Nee, K. Y. Lau, and R. S. Muller, "A flat high-frequency scanning micromirror," in Proc. Solid-State Sensor and Actuator Workshop, 2000, pp. 6-9.
[20] X. Huikai, P. Yingtian, and G. K. Fedder, "A CMOS-MEMS mirror with curled-hinge comb drives," Journal of Microelectromechanical Systems, vol. 12, no. 4, pp. 450-457, 2003.
[21] U. Hofmann, J. Janes, and H.-J. Quenzer, "High-Q MEMS resonators for laser beam scanning displays," Micromachines, vol. 3, no. 2, pp. 509-528, 2012.
[22] N. Asada, H. Matsuki, K. Minami, and M. Esashi, "Silicon micromachined two-dimensional galvano optical scanner," IEEE Transactions on Magnetics, vol. 30, no. 6, pp. 4647-4649, 1994.
[23] K. G. K. Periyasamy, V. J. Tan, S. He, and N. Kourtzanidis, "External electromagnet FPCB micromirror for large angle laser scanning," Micromachines, vol. 10, no. 10, p. 667, 2019.
[24] H. Lei, Q. Wen, F. Yu, Y. Zhou, and Z. Wen, "FR4-based electromagnetic scanning micromirror integrated with angle sensor," Micromachines, vol. 9, no. 5, p. 214, 2018.
[25] J. Y. Hwang, J. U. Bu, and C. H. Ji, "Low power electromagnetic scanning micromirror for LiDAR system," IEEE Sensors Journal, vol. 21, no. 6, pp. 7358-7366, 2021.
[26] K. Uchino, "Piezoelectric actuators 2006," Journal of Electroceramics, vol. 20, no. 3, pp. 301-311, 2008.
[27] J. Rödel and J.-F. Li, "Lead-free piezoceramics: Status and perspectives," MRS Bulletin, vol. 43, no. 8, pp. 576-580, 2018.
[28] G. Pillai and S. S. Li, "Piezoelectric MEMS resonators: a review," IEEE Sensors Journal, vol. 21, no. 11, pp. 12589-12605, 2021.
[29] K. Ikegami, T. Koyama, T. Saito, Y. Yasuda, and H. Toshiyoshi, A biaxial PZT optical scanner for pico-projector applications (SPIE OPTO). SPIE, 2015.
[30] B. Xu, Y. Ji, K. Liu, and J. Li, "Piezoelectric MEMS mirror with Lissajous scanning for automobile adaptive laser headlights," Micromachines, vol. 13, no. 7, p. 996, 2022.
[31] Y. Liu, L. Wang, Y. Su, Y. Zhang, Y. Wang, and Z. Wu, "AlScN piezoelectric MEMS mirrors with large field of view for LiDAR application," Micromachines, vol. 13, no. 9, p. 1550, 2022.
[32] C. C. Tsai, Z. H. Li, Y. T. Lin, and M. S. C. Lu, "A closed-loop controlled CMOS MEMS biaxial scanning mirror for projection displays," IEEE Sensors Journal, vol. 20, no. 1, pp. 242-249, 2020.
[33] A. S. Algamili et al., "A review of actuation and sensing mechanisms in MEMS-based sensor devices," Nanoscale Research Letters, vol. 16, no. 1, p. 16, 2021/01/26 2021.
[34] A. Vergara, T. Tsukamoto, W. Fang, and S. Tanaka, "Feedback control of thin film PZT MEMS actuator with integrated buried piezoresistors," Sensors and Actuators A: Physical, vol. 332, p. 113131, 2021/12/01/ 2021.
[35] J. Grahmann, A. Dreyhaupt, C. Drabe, R. Schrödter, J. Kamenz, and T. Sandner, MEMS-mirror based trajectory resolution and precision enabled by two different piezoresistive sensor technologies (SPIE OPTO). SPIE, 2016.
[36] A. D. Yalcinkaya, H. Urey, D. Brown, T. Montague, and R. Sprague, "Two-axis electromagnetic microscanner for high resolution displays," Journal of Microelectromechanical Systems, vol. 15, no. 4, pp. 786-794, 2006.
[37] H. Urey, D. Wine, and T. Osborn, Optical performance requirements for MEMS-scanner-based microdisplays (Micromachining and Microfabrication). SPIE, 2000.
[38] H. Miyajima et al., "A MEMS electromagnetic optical scanner for a commercial confocal laser scanning microscope," Journal of Microelectromechanical Systems, vol. 12, no. 3, pp. 243-251, 2003.