1、附件5論文中英文摘要作者姓名：顧磊論文題目：高性能MEMS射頻無源器件與三維硅微機械加工技術作者簡介：顧磊，男1980年4月出生，2004年4月師從中國科學院上海微系統與信息技術研究所李昕欣研究員，于2007年7月獲博士學位。中 文 摘 要片上集成電感、互感和可調電容是射頻集成電路中三種最重要的射頻無源元件，在整個電路系統中起著決定性的作用，是單片RF集成電路如壓控振蕩器（VCOs）、低噪聲放大器(LNAs)及無源濾波器中的關鍵性部件，在個人移動通訊、全球定位系統（GPS）以及衛星信號接收等高頻電路系統中占有重要的地位。利用微機械技術研究射頻無源器件是目前MEMS研究領域的熱點之一。體微機械、

2、表面微機械以及LIGA技術是MEMS領域重要的三種加工手段，幾種加工方式的融合與實現片上集成也是目前MEMS加工領域的發展方向。本論文工作主要研究硅基三維微機械結構制造及射頻關鍵器件的研制技術。一方面針對目前電訊用RFIC的高性能無源元件，如電感、互感和可變電容。所開發的低溫工藝可以與射頻CMOS工藝相兼容，同時利用MEMS技術解決了硅襯底損耗等問題，實現了高性能的RF電感、互感和可變電容等關鍵元件，另一方面還針對微納操縱和精確定位系統需求的X-Y微移動平臺，用深溝側壁隔離（Trench-sidewall） MEMS工藝形成具有微米級移動范圍和納米級定位精度的高性能X-Y微移動載臺，為微米電子

3、機械系統進入到納米電子機械系統研究提供了基本的操作平臺，同時新型的電絕緣技術使該微平臺可以在普通硅片上制作實現，替代SOI硅片，大大降低了制造成本。主要研究工作和成果分項歸納為：1）在國際上首次報道一種采用低溫CMOS兼容工藝制造的嵌入式懸浮螺管 (Concave-Suspended Solenoid) 結構電感和互感（L.Gu, X.Li, IEEE Trans. Electron Devices 54，2007，pp.882；L.Gu, X.Li,IEEE Trans. Microwave Theory Tech. 55，2007，pp.1237）。為了便于封裝以及后續加工，電感或互感線圈

4、嵌入在硅片內部，電感線圈周圍的硅材料被XeF2氣體各向同性腐蝕去除，整個線圈結構通過兩邊伸出的二氧化硅薄膜支撐（發明專利CN200610029276.8李昕欣,顧磊）。由于線圈周圍的硅都被腐蝕移除，電感的襯底損耗極低，大大提高器件的高頻性能。而采用銅電鍍工藝又顯著降低線圈的歐姆損耗。上面兩個 1因素使得新型電感和互感的Q值和諧振頻率得到顯著提高。兩邊二氧化硅膜支撐也使得整個懸浮結構更加結實，制作的器件在10000g加速度沖擊試驗下完好無損。利用有限元分析軟件ANSYS仿真100g的環境加速度以及80攝氏度環境溫度改變下的電感值變化，分析得到的變化值比目前國際上報道最好的懸浮結構還要低一個量級。

5、針對該創新結構嵌入式懸浮螺管電感和互感，建立了集總和準分布兩種電路模型，模型與測量結果相吻合，能夠指導電感或互感的優化設計 (L.Gu, X.Li, IEEE J-MEMS 16，2007，pp.1162)。電感高頻性能測量結果表明2.47nH電感的Q值在2GHz時高達54，自諧振頻率超過15GHz，優于已發表的各種CMOS兼容微機械片上電感。在電感制造基礎上進一步工藝創新，設計制造出雙螺旋結構懸浮互感，建立了器件模型（L.Gu, X.Li,IEEE Trans. Microwave Theory Tech. 55，2007，pp.1237）。互感有效帶寬測量值為14Ghz到16GHz，有效增

6、益（可以作為評價互感性能的綜合指標）為0.89，在國際報道的片上集成互感中性能最好。該電感和互感創新技術2006年入選著名的國際電子器件大會（IEDM）作報告 (L.Gu, X.Li, IEEE IEDM 2006，pp.521) 。2）針對該創新結構，提出并實現了各種經常使用的電感或互感設計方法 (L.Gu, X.Li,IEEE MEMS 2007，pp.771)，針對更大的電感值，為節省芯片面積，首尾串聯的緊密型電感結構是合適的選擇；反之如果希望進一步提高性能但對芯片面積要求不高，則“S”型結構更加合適；為避免電感線圈形成的電磁場對周圍電路的影響，提出并實現了一種閉合回路結構，HFSS軟件

7、分析表明該結構能夠將磁力線幾乎全部限制在線圈內部(L.Gu, X.Li, Microelectron. Eng.85，2008，pp.697)。此外，為了進一步提高電感或互感的性能及一致性，提出并實現了一種帶有絕緣溝槽的微結構，通過精確限制XeF2氣體腐蝕區域的技術，顯著提高了器件性能的一致性。通過在焊盤底部放置厚二氧化硅層減少引線焊盤引入的寄生效應，使得器件在滿足片上集成需要的之外還可以作為高性能分立器件倒裝焊封裝到SiP射頻電路中 (L.Gu, X.Li, Microw. Opt. Technol. Lett. 50,2008,pp.2442)。3）針對射頻集成電路用微機械可變電容存在的問

8、題，提出了一系列的解決辦法和創新技術。為了減少串聯電阻、降低工藝復雜度并與Post-CMOS工藝兼容，發明一種低應力多層金屬電鍍技術來制造懸浮可變面積及可變間距梳齒電容 (L.Gu, X.Li, Microw. Opt. Technol. Lett. 50,2008,pp.2469)。利用金屬鎳優異的機械性能，我們采用鎳制作器件結構，在金屬鎳的表面電鍍一薄層金用來降低串聯電阻并防止鎳在空氣中氧化。為降低襯底損耗，可變電容結構底部硅用干法腐蝕去除，可動結構通過周圍的二氧化硅錨點支撐固定。整個制造過程溫度不超過120攝氏度，僅需兩塊光刻版 （發明專利CN200710044283.3，李昕欣、顧磊）

9、。器件測量結果為：4V電壓驅動下，電容值的可調比高達2.98:1，1GHz時的Q值為103，2GHz時的Q值為46.2，優于目前報道的各種CMOS兼容片上集成微機械可變電容。為了避免驅動電壓端口對射頻信號端口的影響，提出并實現了一種新的相互絕緣式可變電容結構(L.Gu, X.Li, Electronics Lett. 43,2007,pp.808)。電容驅動端與敏感電容端通過二氧化硅薄膜橋實現機械上相連，但電學上相互絕緣。該結構消除了直流偏置電路對可變電容性能的影響，提高了可變電容在電路布局中的靈活性，測量得到4V電壓驅動下，電容的可調比高達3.18:1，Q值在1GHz時為115.0，在2GH

10、z時為40.2。4）國際上首次提出并實現一種旋轉式微結構可變電容，能夠抵抗外界環境振動或沖擊對可變電容穩定性的影響 (L.Gu, X.Li, IEEE Electron Device Letters 29,2008,pp.195)。當施加靜電驅動力時，梳齒電容的運動方向是沿著器件中心軸旋轉。這種結構只有受到軸向力才會產生明顯形變，而外界環境加速度的影響幾乎都為水平單一方向，很少會產生沿中心軸旋轉加速度的干擾，故該結構能夠有效抑制移動通訊系統應用時環境振動沖擊對器件的影響，顯著提高了可靠性(發明專利CN200710045457.4,李昕欣、顧 磊)。該旋轉結構在10g環境加速度下，電容的變化值比

11、傳統微機械可變電容（直向運動）的電容變化值低兩個量級以上。性能測試得到12V電壓下，可變電容可調比為2.1:1，Q值在2GHz時仍高達35.2。以上MEMS片上可調諧電容的相關成果又一次入選2007年國際電子器件大會（IEDM）做報告(L.Gu, X.Li, IEEE IEDM 2007，pp.427)。本論文在射頻電路用高性能MEMS器件方面的研究成果得到國際同行高度重視，作為中國學者，首次被邀請在2008年IEEE RFIC國際會議做特邀報告（X.Li, L.Gu，IEEE RFIC-2008，pp.163）。5) 首次采用深溝側壁（Trench-sidewall）MEMS集成工藝技術在單

12、一硅片上成功制造微移動平臺 (L.Gu,et al, J Micromech. Microeng. 85,2008,pp.697)。采用的Trench-sidewall MEMS技術能夠取代價格昂貴的SOI襯底，將靜電驅動，電容、壓阻信號檢測部分集成在單硅片上，并且能夠對一些功能進行自檢和反饋控制，提高的器件的精度和可靠性，降低制造成本 (X.Li，L.Gu，IEEE Sensors Journal, 8,2008,pp.1992)。顯微鏡測量制造出的兩維微位移載臺，在23V驅動電壓下載臺移動范圍為20×20微米2。為車輛載臺的移動定位精度，一種加熱SPM探針納米壓印方法被設計和用于

13、測量。測量結果顯示位移精度優于18nm，為將來的微電子機械系統研究進入到納電子機械系統研究提供了必要的操作和測試平臺工具。本論文工作用原始創新的關鍵技術解決了三維MEMS結構集成制造的復雜難題。特別是與CMOS集成電路工藝兼容的片上集成高性能射頻無源器件技術，所取得的成果獲得國際學術界的認可，所開發的可實用化技術也在微電子產業界獲得轉讓和推廣應用。論文的相關學術成果兩度發表在國際電子器件領域論文錄取最為困難的“國際電子器件會議”（International 3Electron Device Meeting,簡稱IEDM，在IEDM五十多年歷史中我國被錄取發表的論文僅寥寥數篇）。此外，論文多次發

14、表在包括IEEE E-D Lett., IEEE T-ED, IEEE J-MEMS, IEEE T-MTT等電子信息領域國際核心期刊上，引起了國際同行的重視。相關成果受2008年領域國際著名會議IEEE International RFIC Symposium邀請作特邀報告，是我國首次在該會議獲邀作邀請報告。另外包括IEEE ED Society的副主席和IEEE Fellow等國際著名學者紛紛主動就該成果進行高性能RF集成電路技術合作研發。論文成果中包括三項核心發明專利（一項授權，兩項公開）。香港主版上市公司上海先進半導體制造有限公司（ASMC）等企業就本論文的成果已經與我們展開了專利技術

15、轉讓來實現微電子制造產品技術。根據該技術應用研發內容，上海市科委近期確立了重點項目進行支持。這種用自主創新的技術來提升我國微電子企業的產業技術水平對推動我國微電子事業的發展具有重要意義。本文所作的研究工作，在MEMS三維復雜集成結構制造方面取得了突破性成果，對于實現高性能射頻集成電路、通訊系統以及納米操縱等具有重要的學術價值和應用價值，有助于我國在信息技術領域取得突出的、有特色的進展，獲得重大經濟效益。規定期限內相關成果形成的論文和專利列表如下：論文：1. Lei Gu, Xinxin Li, Variable Capacitors and Tunable LC-Tanks Formed by

16、 CMOS-Compatible Metal MEMSfor RF ICs, IEDM 2007 - 53th IEEE International Electron Device Meeting, Washington DC，USA, 10-13 Dec., 2007, pp.427-430.2. Lei Gu, Xinxin Li, A Post-CMOS Concave-Suspending MEMS Process in Standard Silicon Wafers forHigh-Performance Solenoidal-DNA-Configured Micro-Transfo

17、rmers, IEDM 2006 - 52th IEEE International Electron Device Meeting 2006, San Francisco, CA, USA, Dec. 11-13, 2006, pp. 521-524.3. Lei Gu, Xinxin Li, Rotational-driven RF Variable Capacitors with Post-CMOS Processes, IEEE ElectronDevice Letters, Vol.29, No.2, 2008, pp.195-197.4. Lei Gu, Xinxin Li, Hi

18、gh-Q Solenoid Inductors With a CMOS-Compatible Concave-Suspending MEMSProcess, IEEE Journal of Microelectromechanical Systems, VOL. 16, NO. 5, 2007, pp.1162-1172.5. Lei Gu, Xinxin Li, High-Performance CMOS-compatible Solenoidal Transformers with aConcave-suspended Configuration, IEEE Transactions on

19、 Microwave Theory and Techniques, VOL. 55, NO. 6, 2007, pp.1237-1245.6. Lei Gu and Xinxin Li, Concave-suspended High-Q Solenoid Inductors with an RFIC-compatibleBulk-micromachining Technology, IEEE Transactions on Electron Devices, Vol.54, 2007, pp.882-885.7. Lei Gu, Xinxin Li, Haifei Bao, Bin Liu,

20、Yuelin Wang, Min Liu, Zunxian Yang, Baoluo Cheng,Single-Wafer-Processed Nano-Positioning XY-Stages with a Trench-Sidewall Micromachining Technology, J. Micromech. Microeng., 16 (2006) 13491357.8. L. Gu and X. Li, Post-CMOS micromachined RF varactor with mutual-isolated large-tuning capacitor andlow-

21、voltage actuator, Electronics Letters, Vol. 43, No. 15, 2007, pp.808-809.9. Lei Gu, Xinxin Li, On-chip embedded toroidal-solenoid inductors and transformers formed by post-CMOSmicromachining techniques, Microelectronic Engineering, Vol. 85, 2008, pp.697-703.10. Lei Gu, Zhengzheng Wu, Xinxin Li, Post

22、-CMOS compatibly micromachined high-performance on-chipair-core solenoidal inductors, Microwave and Optical Technology Letters, Vol. 50, 2008, pp.2442 2446.11. Lei Gu, Zhengzheng Wu, Xinxin Li, Post-CMOS micromachined nickel tunable-capacitors with a large 4tuning-range under low actuating voltage,

23、Microwave and Optical Technology Letters, Vol. 50, 2008, pp.2469 2472.12. Lei Gu, Xinxin Li, An wide-range tunable on-chip radio-frequency LC-tank formed with a post-CMOS13. Lei Gu, Xinxin Li, CONCAVE-SUSPENDED HIGH-Q SOLENOID INDUCTORS WITH A POST-CMOSMEMS PROCESS IN STANDARD SILICON WAFERS, IEEE M

24、EMS-07 - the 20th IEEE International Conference on Micro Electro Mechanical Systems, Kobe, Japan, Jan. 21-25, 2007, pp.771.14. Lei Gu, Xinxin Li, Haifei Bao, Bin Liu, Yuelin Wang, Min Liu, Zunxian Yang, Baoluo Cheng, ASingle-Wafer-Processed XY-Stage Fabricated with Trench-sidewall Doping and Refille

25、d-Trench Isolating Technology, IEEE NEMS-06 - the 1st IEEE International Conference on Nano/Micro Engineered and Molecular Systems, Jan. 18-21, 2006, Zhuhai, China, pp.860-863.15. (邀請報告) Xinxin Li, Lei Gu, (INVITED) Hi-Performance RF passives Using Post-CMOS MEMSTechniques for RF SoC, IEEE RFIC-2008

26、 - 2008 IEEE Radio Frequency Integrated Circuits Symposium, June 15-17, 2008, Atlanta, GA, USA, pp.163-166. (注：第一作者為申請者的導師)16. Xinxin Li, Lei Gu, Yuelin Wang, Heng Yang, Single-wafer-processed Self-testable High-g Accelerometerswith Both Sensing and Actuating Elements Integrated on Trench-sidewall,

27、IEEE Sensors Journal, Vol. 8, 2008, pp.1992-1999. (注：第一作者為申請者的導師)17. Xinxin Li, Baoluo Chen, Yuelin Wang, Lei Gu, Jian Dong, Xiaohong Ge，A trench-sidewallsingle-wafer-MEMS technology and its typical application in high-performance accelerometers，IEDM 2004-50th IEEE International Electron Device Meet

28、ing, San Francisco, CA ,13-15 Decmber，2004，pp.43-46. (注：第一作者為申請者的導師)18. Xinxin Li, Wei Xu, Ying Chen, Le Luo, Lei Gu, Min Liu, Baoluo Cheng, and Yuelin Wang,Single-wafer-processed trench-sidewall integration and its application in a micro resonant detector for vacuum monitoring, J. Vac. Sci. Technol

29、. B 24 (1), Jan/Feb 2006, pp16-19. (注：第一作者為申請者的導師) 專利：1. 一種CMOS工藝兼容的嵌入懸浮螺管結構電感或互感的制作方法, CN200610029276.8, 李昕欣、顧磊（已授權）2. 一種CMOS工藝兼容的懸浮式可變電容的制作方法，CN200710044283.3，李昕欣、顧磊 （法律狀態：實質審查的生效；公開（公告）號：101110354；公開（公告）日：2008-01-23）3. 一種抗環境振動的適用于移動電信的MEMS片上可變電容，CN200710045457.4, 李昕欣、顧 磊 （法律狀態：實質審查的生效；公開（公告）號：101

30、154505；公開（公告）日：2008-04-02）關鍵詞：微電子機械系統，射頻無源器件，電感，互感，可變電容,可調諧諧振器，X-Y兩維微移動平臺，微機械加工High-performance MEMS RF passive components and siliconmicromachined technologyLei GuABSTRACTOn-chip inductors, transformers and tunable capacitors are most important passive components in RF integrated circuits and play

31、key roles for designing VCO (voltage control oscillator), LNA (low noise amplifier) and passive filter or resonator. Besides, personal mobile communication, GPS (global position system), and satellitic signal receiver also need these high-performance devices, namely high Q-factor of inductors/tunabl

32、e capacitors and high available gain of transformers. Presently, it is a hotspot for studying RF passive components by using MEMS technology. Bulk, surface micromachining and LIGA technique are three essential method of fabrication. Several kinds of processes infused and integrated are also the dire

33、ction for further MEMS research.In this dissertation, we mainly study the 3-D micromachined process based on silicon substrate and research of key RF passive components. On the one hand, some high performance RF components are implemented for telecommunications by using a concise process, such as in

34、ductors, transformers and tunable capacitors. The novel process could be compatible with CMOS process with low temperature. Moreover, the substrate loss is suppressed deeply by selective removing silicon surrounding the devices. On the other hand, a nano-precision XY-stage is designed and fabricated

35、 with trench-sidewall technology. Moreover, the XY-stage is formed on a single wafer instead of SOI wafer to reduce the cost of the fabrication. The stage is an elementary operation method for further research from MEMS (microelectricmechanical system) to NEMS (nanoelectricmechanical system) researc

36、h. The main work and contributions are as follows:1) In order to improve the performance of inductors and transformers, concave-suspended solenoid structures are proposed and formed by low temperature CMOS compatible process. To our best knowledge, these structures are reported firstly in the world.

37、 To facilitate the package and post-fabrication, the coils of inductors or transformers are embedded into the silicon substrate. The silicon surrounding the 6coils are etched and removed by gaseous XeF2. Therefore, the substrate loss of thedevice is suppressed due to the silicon surrounding coils re

38、moved. Moreover, the ohmic loss also reduced by using the copper plated process. Both factors improve the Q-factor and resonant frequency. The whole structure is sustained with protruding silicon oxide film on the both sides of the structure. The robust structure can be survived even under a shock o

39、f 10000g acceleration. By using finite element software ANSYS, the deformation of coil is one order smaller than other suspended inductors under 100g acceleration and 80 centigrade temperature changed. According to these proposed concave-suspended solenoid inductors and transformers, lumped and quas

40、i-distributed circuit models are given. The simulated results based on circuit model can agree well with the measurement and be used to design and optimize the inductors and transformers. The measured Q-factor, the inductance and resonant frequency of the concave-suspended solenoid inductor are 542G

41、Hz, 2.47nH at low frequency and more than 15GHz, respectively. These performances are better than most of other micromachining inductors. We also fabricate some transformers which formed with the similar process. For the transformer, available gain can be defined as the ratio between the power deliv

42、ered to the load and the power input to the network. It can be considered as an important figure-of-merit for overall evaluation of the RF transformers. The available gain of our present transformer is as high as 0.89 which is better than all other reported transformers. The available bandwidth is f

43、rom 14 to 16GHz.2) Different layouts of inductors and transformers are proposed for different applications. For the high inductance with small area occupation, a compact structure made by connecting several one column inductors in series is better choice. For the high inductance with high performanc

44、e, an “S”shaped structure is a suitable choice with a little bigger area occupation. In order to eliminate the effect of electromagnetic interference and noise coupling with neighboring RF components, several closed loop solenoid inductor are implemented. With simulation of HFSS (Ansoft company soft

45、ware), these structure can confine the magnetic flux into a close-path. The structure can also avoid the flux intersecting with metals and semiconductor materials where eddy currents are easily induced. In order to improve the uniformity of the performance, a kind of structure with silicon oxide ref

46、illed trenches is given, which can define the region for XeF2 gaseous etching. The oxideblock beneath the test pad can suppress the substrate parasitics. This structure can be used not only on-chip integration but as an off-chip for flip-chip package.3) Some new structures and process are presented

47、for solving problems existed in conventional MEMS tunable capacitors. In order to reduce the series resistance 7and simply the fabrication, low stress multi-metal electroplated technology (also called metal MEMS technology) is proposed and used to fabricate the suspended tunable capacitor with comb

48、drivers. Electroplated nickel is used as the structure material due to its excellent mechanical properties. A thin gold film is covered on the surface of the nickel for long-term antioxidation in the air. After finishing the whole structure, the silicon substrate beneath the capacitive combs is also

49、 removed by XeF2 dry etching to for the same reason of suppressing the substrate loss. The structures are sustained by surrounding silicon oxide anchors. A suspension gap distance from the silicon substrate is formed. The temperature during the whole fabrication is below 120 centigrade. Only two mas

50、ked are required. Under 4V driving voltage, the tuning ratio is 2.98:1. The Q-factor is 103 at 1GHz and 46.2 at 2GHz, which is better than most of micromachining tunable capacitor.Most of the previously reported MEMS tunable capacitors share a common electric terminal with the electrostatic actuator

51、. This common-ground configuration confines the flexibility of RFIC design. Moreover, the DC driving voltage interferes with the input RF signal especially in high power application. To overcome this limitation, the present technique electrically isolates the two parts at the middle of the linking b

52、ars with a patterned SiO2 bridge. The bridge just connects the two terminals mechanically but isolates each other electrically. This allows a greater flexibility in RF circuit layout. Under 4V driving voltage, the tuning ratio is 3.18:1. The Q-factor is 115 at 1GHz and 40.2 at 2GHz4) To date, a draw

53、back of the developed micromachined tunable capacitors lies in the mechanical instability induced by the straight-line-driven comb structures. For achieving a large tuning ratio under a low driving voltage, the researches have always designed the suspension springs as flexible as possible. When used

54、 in a mobile system like cell phone, such a mechanically instable capacitor will be inevitably influenced by the environmental vibratory/acceleration. On the contrary, rigid suspended beams require high driving voltage for getting wide tuning range. This is a dilemma in the design of micromaching tu

55、nable capacitors. To solve this problem, this dissertation develops, for the first time, a rotationally driven tunable capacitor. The rotational structure features a low stiffness in tangential direction for capacitance tuning but a much higher stiffness along radial directions for anti-vibration, t

56、hereby, exhibiting both high tuning-range under low-voltage and high resist against the axial vibration and acceleration. Generally, the environmental acceleration is applied along the straight direction. Therefore, the rotational structure can effectively suppress the environmental vibratory/accele

57、ration. By using ANSYS simulation, the comb moving distance along 8the electrostatic driving direction is about two orders of magnitude lower than that of the conventional straight-moving tunable capacitors. Under 12V driving voltage, the tuning range of rotational capacitor is 2.1:1. The Q-factor i

58、s 35.2 at 2GHz.5) Besides the RF passive components, a XY-stage is firstly presented on a single silicon wafer with trench-sidewall MEMS integrated technology. The trench-sidewall technology can be used to integrated piezoresistive, capacitive sensing and electrostatic actuator on a single silicon w

59、afer instead of expensive SOI or SOG wafer. Moreover, the reliability of device can be improved by self-testing and feed back control. By using measured microscope, the moving range of the XY-stage is tested as 20×20m2 under a driving voltage of 23V. In order to get a precision of movement, a nano-print system is designed and used to measure the XY-stage. Limited by the radius of the nanometric tip, the resolution of the tip position