以CMOS-MEMS製程平台實現高性能微機械共振器電路

Performance Enhancement of Integrated Micromechanical Resonators Using Generalized CMOS-MEMS Platforms

陳文健(Wen-Chien Chen)

指導教授 ： 方維倫 ； 李昇憲

國立清華大學/工學院/動力機械工程學系/博士(2013年)

摘要

金氧半導體微機電(CMOS-MEMS)技術藉由CMOS製程能同時於單一晶片上(On-Chip)完成積體電路IC與MEMS元件之製作，具有縮減面積、低雜訊，及穩定的標準化製程…等優點。本論文即採用此整合式技術開發多種具備優異性能的電容式(Capacitively-transduced)高頻(HF)即甚高頻(VHF)微機械共振器，應用於感測器、時基(timing reference)及射頻(Radio Frequency, RF)等元件。為了達到此研究目標，本論文成功開發二氧化矽(SiO2)濕式蝕刻(wet etching)及金屬(Metal)濕式蝕刻(wet etching)此兩種同時與0.35 m 2P4M及0.18 m 1P6M CMOS製程相容之懸浮後製程(releasing post-process)，並分別製作出多種結構設計與不同材料組成的金屬型式以及二氧化矽型式之整合式微機械共振器。除了開發製程平台，本論文同時致力於MEMS共振器之性能強化；藉由(1)間隙(Gap)縮減機制、(2)高Q值材料與細小支撐結構、(3)二氧化系與金屬之複合材料、(4)獨特結構、(5)陣列式共振器與體模態振動，及(6)全差分式(Fully-differential)電性架構之設計；分別改善共振器的關鍵問題如運動阻抗、品質因子、熱穩定、頻率調控、功率負載能力與feedthrough效應，成功製作出相較其他文獻之元件，具有相對低運動阻抗、高Q值、溫度補償能力、類線性頻率調控機制、高功率負載能力及大訊雜比之CMOS-MEMS微機械共振器。此外；本論文亦發展一套通用被動式溫度補償理論模型，可設計複合結構體模態共振器之溫度係數。本論文增強CMOS-MEMS微機械共振器性能之成果將有助於未來整合式微機械震盪器(Oscillator)之設計，並應用於消費性電子產品中之時基(Timing reference)與頻率參考元件。

關鍵字

金氧半導體微機電 ； 射頻微機電 ； 製程平台 ； 全整合式 ； 電容式 ； 微機械共振器 ； 甚高頻 ； 吸附效應 ； 次微米 ； 頻率調控 ； 全差分 ； 二氧化矽結構 ； 音叉 ； 方形板 ； 體聲波 ； 高Q值 ； 溫度補償 ； 複合結構

並列摘要

The CMOS-MEMS technology with many advantages, including smaller footprints size, without noise from bond pad, and standard foundry process, is utilized in this dissertation to develop various capacitively-transduced HF/VHF micromechanical resonators with several unique performances targeted for sensor, timing reference, and RF applications. To attain this goal, two generalized releasing post-process, such as oxide wet etching and metal wet etching techniques, compatible with 0.35 m 2P4M and 0.18 m 1P6M CMOS processes, were successfully developed to fabricated metal-type and oxide-type integrated resonators, respectively, with diverse structural designs as well as different material configurations. In addition to post-process development, this dissertation attend to improve main consideration of MEMS resonator design issues, such as motional impedance (Rm), quality factor (Q), thermal stability, frequency tuning, power handling capability, and feedthrough cancellation, through (1)gap reduction mechanism, (2)high-Q material and tiny-support, (3)oxide-metal composite, (4)elegant structural design, (5)resonator-array and bulk mode vibration, and (6)fully-differential electric setup, respectively, successfully demonstrating CMOS-MEMS resonators with better characteristics of relative low-Rm, high-Q, temperature compensated capability, quasi-linear frequency tuning ability, high power handling, large signal to noise ratio, than previous CMOS-MEM works. In addition, this dissertation also derive a generalized theoretical model of passive temperature compensation for composite bulk mode resonators, capable of further controlling its temperature coefficient of frequency (TCf) Such performance improved results might benefit the future integrated micromechanical oscillator design for timing or frequency reference in consumer electronics.

並列關鍵字

CMOS-MEMS ； RF-MEMS ； platform ； fully-integrated ； capacitively-transduced ； micromechanical resonator ； VHF ； pull-in ； deep-submicron ； frequency tuning ； fully-differential ； oxide structure ； tuning fork ； square plate ； bulk acoustic ； High-Q ； temperature compensation ； composite structure

參考文獻

[2] C. T.-C. Nguyen and R. T. Howe, “An integrated CMOS micromechanical resonator high-Q oscillator,” IEEE J. Solid-State Circuits, vol. 34, no. 4, pp. 440-455, April 1999.

[3] J. H. Smith, S. Montague, J. J. Sniegowski, J. R. Murray, and P. J. McWhorter, “Embedded micromechanical devices for the monolithic integration of MEMS with CMOS”, Tech. Digest, IEEE Int. Electron Devices Mtg., Washington, D.C., Dec. 10-13, 1995, pp. 609-612.

[5] W.-L. Huang, Z. Ren, Y.-W. Lin, H.-Y. Chen, J. Lahann, and C. T.-C. Nguyen, “Fully monolithic CMOS nickel micromechanical resonator oscillator,” Tech. Digest, 21st IEEE Int. Conf. on Micro Electro Mechanical Systems (MEMS’08), Tucson, Arizona, Jan. 13-17, 2008, pp.10-13.

[7] C. T.-C. Nguyen, “Frequency-selective MEMS for miniaturized low-power communication devices (invited),” IEEE Trans. Microwave Theory Tech., vol. 47, no. 8, pp. 1486-1503, Aug. 1999.

[12] C.-C. Lo, F. Chen, and G. K. Fedder, “Integrated HF CMOS-MEMS square-frame resonators with on-chip electronics and electrothermal narrow gap mechanism,” Tech. Digest, Transducers’05, Seoul, Korea, June 5-9, 2005, pp. 2074-2077.