前沿：Chip发表武汉大学刘胜院士团队最新成果 | 蜂窝状晶格声子晶体提升压电微腔恒温控制MEMS谐振器Q值

文章来源：FUTURE | 远见

图1 | 声子晶体微加热腔恒温控制压电谐振器设计。a, 蜂窝状晶格PnC的晶胞。b, 蜂窝状晶格PnC布里渊区的不可约部分。c, 蜂窝状晶格PnC的能带结构。d, PnC和参考结构的延迟线模型。e, 延迟线的传输曲线。f, PnC微腔恒温控制压电谐振器的三维示意图。g, 仿真的温度分布。h, PnC微加热腔谐振器的自加热特性。

图2 | 不同器件长度的谐振器传输响应测量结果及其平均值。a, Q_l。b, IL。c, Q_u。d, R_m。

图3a展示微加热腔恒温控制压电谐振器的谐振频率与温度的关系。谐振器的温度拐点高达131 ℃。高温度拐点使谐振器能够在更宽的温度范围内有效运行，满足高端微加热腔恒温控制谐振器的需求。图3b描述了室温下加热功率变化时微加热腔恒温控制谐振器的谐振频率和Q值的关系。由于声子晶体带隙的存在，带有PnC微加热腔的压电谐振器与不带PnC微加热腔压电谐振器相比在高温下仍然表现出更高的Q值。图3c显示，在40 ℃温度下测量60分钟，微加热腔恒温控制压电谐振器频率变化小于±10 ppb。图3d比较了基于Type-A和Type-B谐振器的振荡器的Allan方差。Type-A和Type-B振荡器的最佳频率不稳定性分别为2.91 ppb和0.41 ppb。频率稳定性的提高凸显了带有PnC微加热腔的谐振器在构建高稳定性时钟方面的潜力。

图3 | 真空封装MEMS谐振器的测量结果。a, 测量的频率-温度特性。b, 测量的谐振频率和无负载Q与加热功率的关系。c, 测量的微加热腔恒温控制谐振器频率稳定性。 d, 在40 ℃下测量1小时以上的压电MEMS谐振器振荡器的Allan方差比较。

Microelectromechanical systems (MEMS) resonators have demonstrated unique advantages as frequency references to replace quartz resonators, because of their compact size, high reliability, and compatibility with semiconductor manufacturing process. Despite these advantages, temperature coefficients of frequency (TCFs) of silicon-based MEMS resonators are quite large. The TCF of resonator can be achieved by the micro-oven-controlled temperature compensation scheme to achieve zero TCF (turnover point) at a high temperature，and stands out as a particularly effective method for achieving ppb-level frequency stability. Thin-film piezoelectric-on-silicon (TPoS) resonators combine the benefits of high electromechanical transduction factor from piezoelectric materials with low intrinsic losses of single-crystal silicon (SCS), resulting in both low R_m and moderately high Q. Recent advancements in TPoS resonators have focused on incorporating micro-oven-controlled designs to achieve highly stable and precise frequency references. However, the Q degradation problem presents a significant challenge for the current micro-oven-controlled resonators based on the TPoS platform^2,3.

Fig. 1 | Design of the PnC micro-oven controlled piezoelectric resonator. a, A unit cell of the honeycomb lattice PnC. b, The irreducible part of the Brillouin zone for honeycomb lattice PnC. c, Band structures of the honeycomb lattice PnC. d, Delay line models of PnC and reference structures. e, Transmission curves of the delay lines. f, Three-dimensional schematic view of the PnC micro-oven controlled piezoelectric resonator. g, Simulated temperature distributions. h, Self-ovenization characteristic for the resonator with PnC micro-oven.

Fig. 2 | Transmission response measurement results of the resonators and their average values with different device lengths. a, Q_l. b, IL. c, Q_u. d, R_m.

Fig. 3a displays the resonant frequency of the micro-oven-controlled piezoelectric resonator versus temperature. The resonator presents a high turnover point of 131 ℃. The high turnover point enables the resonator to operate effectively over a broader temperature range, meeting the demand for high-end micro-oven-controlled resonator. Fig. 3b depicts the resonant frequency and unloaded Q of the micro-oven-controlled piezoelectric resonator under varying heating power at room temperature. The piezoelectric resonator with micro-oven still exhibits superior high Q_u compared with the bare piezoelectric resonators due to the existence of the PBG. The frequency stability of the micro-oven-controlled piezoelectric resonator was measured for 60 min at a stable temperature of 40 ℃. Fig. 3c shows that the frequency variation is less than ±10 ppb over the measurement period. Fig. 3d compares the extracted Allan deviations of oscillators based on Type-A and Type-B resonators. The best frequency instabilities of Type-A and Type-B oscillators are 2.91 ppb and 0.41 ppb, respectively. The improvement in short-term stability highlights the potential of resonators with PnC micro-oven to create high-stable clocks.

Fig. 3 | Measurement results of the vacuum-packaged MEMS resonators. a, Measured frequency-temperature characteristic. b, Measured resonant frequency and unloaded Q versus heating power. c, Measured frequency stability with micro-oven control. d, Comparison of Allan deviations of fabricated piezoelectric MEMS resonator-based oscillators measured over 1 hour at 40 ℃.

参考文献

1. Xiao, Y., Zhu, K., Han, J., Liu, S. & Wu, G. Q-enhancement of piezoelectric micro-oven-controlled MEMS resonators using honeycomb lattice phononic crystals. Chip 3, 100108 (2024).

2. Wu, G.-Q., Xu, J.-H., Ng, E. J. & Chen. W. MEMS resonators for frequency reference and timing applications. J. Microelectromech. Syst. 29, 1137-1166 (2020).

3. Ortiz, L. C. et al. Low-power dual mode MEMS resonators with ppb stability over temperature. J. Microelectromech. Syst. 29, 190-201 (2020).

4. Pillai, G. & Li, S.-S. Piezoelectric MEMS resonators: a review. IEEE Sens. J. 21, 12589-12605 (2021).

5. Frangi, A., Cremonesi, M., Jaakkola, A. & Pensala, T. Analysis of anchor and interface losses in piezoelectric MEMS resonators. Sens. Actuators A Phys. 190, 127-135 (2013). 

论文链接：

https://www.sciencedirect.com/science/article/pii/S2709472324000261

作者简介

肖宇豪，2020年获得武汉大学机械工程学士学位，目前在攻读武汉大学物理电子学博士学位。他的主要研究方向包括MEMS谐振器的设计、制造以及应用。

Yuhao Xiao received the B.E. degree in mechanical engineering from Wuhan University, Wuhan, China, in 2020. He is currently pursuing the Ph.D. degree in physical electronics at Wuhan University, Wuhan, China. His research interests include the design, fabrication and applications of MEMS resonators.

朱科文，2018年获得湖北工业大学包装工程学士学位，2020年获得武汉大学机械工程硕士学位，目前在攻读武汉大学微电子博士学位。他的主要研究方向包括MEMS滤波器的设计、仿真以及加工。

Kewen Zhu received the B.E. degree in packaging engineering from Hubei University of Technology, Wuhan, China, in 2018. He received the M.S. degree in mechanical engineering from Wuhan University, Wuhan, in 2020, where he is currently pursuing the Ph.D. degree in mechanical and electronic engineering. His research interests include the design, simulation, and fabrication of MEMS filters.

韩金钊，2018年获得河南工业大学无机非金属材料工程学士学位，2020年获得武汉大学材料工程硕士学位，2023年获得武汉大学微电子与固体电子学博士学位。他的研究兴趣包括微机械谐振器、滤波器设计。

Jinzhao Han received the B.S. degree in inorganic non-metallic materials engineering from Henan University of Technology, Zhengzhou, China, in 2018. He received the M.S. degree in materials engineering from Wuhan University, Wuhan, in 2020. He received the Ph.D. degree in microelectronics and solid-state electronics from Wuhan University, Wuhan, in 2023. His research interests include the design, simulation, and fabrication of micromechanical resonators and filters.

刘胜，1979年至1986年就读于南京航空航天大学，先后获得学士、硕士学位。1992年毕业于美国斯坦福大学，获工学博士学位。1992年-1998年，在美国佛罗里达(Florida)理工学院、韦恩(Wayne)州立大学任助理教授。1998年获美国韦恩（Wayne） 州立大学机械工程系和制造研究所终身教职，担任电子封装实验室主任。2001年至2013年回国担任华中科技大学微系统研究中心主任、武汉光电国家实验室(筹)微光机电系统研究部负责人。2014年至今，任武汉大学动力与机械学院教授、院长，工业科学研究院执行院长、微电子学院副院长。2023年11月当选为中国科学院院士。

Sheng Liu received the B.S. and M.S. degrees from Nanjing University of Aeronautics and Astronautics, Nanjing, China, in 1983 and 1986, respectively, and the Ph.D. degree from Stanford University, Stanford, CA, USA, in 1992.

His research interests include microsystems (MS)/nanoelectromechanical systems, LED design and manufacturing, system packaging and integration, reliability, smart materials and composites, and mechanics of materials and structures.

吴国强，2008年获得西安电子科技大学电子科学与技术专业学士学位，2013年获中国科学院上海微系统与信息技术研究所（SIMIT）微电子与固体电子学专业博士学位。2014年至2018年在新加坡科学技术研究局（A*STAR）微电子研究院担任研究科学家。现为武汉大学工业科学研究院教授、博士生导师，获批国家自然科学基金优秀青年科学基金项目、湖北省自然科学基金杰出青年项目，入选湖北省高级人才项目，受邀担任IEEE MEMS（2023、2024）执行技术委员会委员。主要研究方向为微纳机电系统（N/MEMS）的设计与集成。目前共发表学术论文80余篇，申请国家发明专利50余项，其中授权发明专利37项，部分技术成功实现应用和产业化。

Guoqiang Wu received the B.Eng. degree in electrical science and technology from Xidian University, Xi’an, China, in 2008, and the Ph.D. degree in microelectronics and solid-state electronics from the Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, Shanghai, China, in 2013. From 2014 to 2018, he was a Research Scientist with the Institute of Microelectronics, Agency for Science, Technology and Research (A*STAR), Singapore. He is currently a Professor with the Institute of Technological Sciences, Wuhan University, Wuhan, China. His research interests include micro/nanoelectromechanical system (N/MEMS) design and integration.

Dr. Wu is the recipient of the Best Dissertation Award of Shanghai in 2014. Together with his students, he was the finalist in best student paper competitions at IEEE MEMS (2021). He is a Senior Member of IEEE and has served as a member of the technical program committee of IEEE MEMS Conference (2023-2024). He has published over 80 research articles and filed over 50 patent applications with 37 of them being granted in US and China, and several of his inventions being successfully commercialized.