C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06MEMS Technologies and Devices for Single-Chip RF Front-EndsClark T.-C. NguyenDept. of Electrical Engineering & Computer ScienceUniversity of MichiganAnn Arbor, Michigan 48105-2122CICMT’06April 25, 2006C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Outline•Motivation: Miniaturization of Transceiversªneed for high-Qªmerged transistor/MEMS process•High-Q Vibrating Micromechanical Resonatorsªclamped-clamped beamsªmicromechanical disksªmicromechanical circuits•Low-loss Micromechanical Switches•Tunable C’s and L’s•ConclusionsC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Wireless PhoneMotivation: Miniaturization of RF Front-Ends26-MHz XstalOscillator26-MHz XstalOscillatorDiplexerDiplexer925-960MHz RF SAW Filter925-960MHz RF SAW Filter1805-1880MHz RF SAW Filter1805-1880MHz RF SAW Filter897.5±17.5MHz RF SAW Filter897.5±17.5MHz RF SAW FilterRF Power AmplifierRF Power AmplifierDual-Band Zero-IF Transistor ChipDual-Band Zero-IF Transistor Chip3420-3840MHz VCO3420-3840MHz VCO90o0oA/DA/DRF PLLDiplexerFrom TXRF BPFMixer IMixer QLPFLPFRXRF LOXstalOscIQAGCAGCLNAAntennaProblem: high-Q passives pose a bottleneck against miniaturizationProblem: high-Q passives pose a bottleneck against miniaturizationC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Multi-Band Wireless HandsetsDuplexer90o0oA/DA/DRXRF ChannelSelect PLLIQLPFLPFRXRF LOIQAGCAGCLNADuplexerRF BPFLNAFrom TXLNALNARF BPFRF BPFRF BPFWCDMAWCDMACDMACDMA--20002000DCS 1800DCS 1800PCS 1900PCS 1900LNARF BPFDuplexerLNARF BPFGSM 900GSM 900CDMACDMAFrom TXFrom TX90o0oIQTank÷ (N+1)/NXstalOscAntenna• The number of off-chip high-Qpassives increases dramatically• Need: on-chip high-Q passivesC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06• Fabrication steps compatible with planar IC processingSurface MicromachiningC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06• Completely monolithic, low phase noise, high-Q oscillator (effectively, an integrated crystal oscillator)• To allow the use of >600oC processing temperatures, tungsten (instead of aluminum) is used for metallizationOscilloscopeOutputWaveformSingle-Chip MEMS/Transistor Integration[Nguyen, Howe 1993][Nguyen, Howe JSSC’99]C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06MEMSMEMSTechnologyTechnologySingle-Chip Integration26-MHz XstalOscillator26-MHz XstalOscillatorDiplexerDiplexer925-960MHz RF SAW Filter925-960MHz RF SAW Filter1805-1880MHz RF SAW Filter1805-1880MHz RF SAW Filter897.5±17.5MHz RF SAW Filter897.5±17.5MHz RF SAW FilterRF Power AmplifierRF Power AmplifierDual-Band Zero-IF Transistor ChipDual-Band Zero-IF Transistor Chip3420-3840MHz VCO3420-3840MHz VCOSingle-ChipTransceiverWrist-watch-sized multi-band wireless device might be possible!Wrist-watch-sized multi-band wireless device might be possible!C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06All High-QPassives on a Single ChipWCDMARF Filters(2110-2170 MHz)CDMA-2000RF Filters(1850-1990 MHz)DCS 1800 RF Filter(1805-1880 MHz)PCS 1900 RF Filter(1930-1990 MHz)GSM 900 RF Filter(935-960 MHz)CDMA RF Filters(869-894 MHz)0.25 mm0.5 mmLow Freq. Reference Oscillator Ultra-High Q TankOptional RF Oscillator Ultra-High QTanksVibrating Resonator62-MHz, Q~161,000Vibrating Resonator62-MHz, Q~161,000Vibrating Resonator1.5-GHz, Q~12,000Vibrating Resonator1.5-GHz, Q~12,000C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Thin-Film Bulk Acoustic Resonator (FBAR)• Piezoelectric membrane sandwiched by metal electrodesª extensional mode vibration: 1.8 to 7 GHz, Q ~500-1,500ª dimensions on the order of 200μm for 1.6 GHzª link individual FBAR’s together in ladders to make filtersAgilent FBAR• Limitations:ª Q ~ 500-1,500, TCf~ 18-35 ppm/oCª difficult to achieve several different freqs. on a single-chiphfreq ~ thicknessfreq ~ thicknessC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Vibrating RF MEMSC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Basic Concept: Scaling Guitar StringsGuitar StringGuitarVibrating “A”String (110 Hz)Vibrating “A”String (110 Hz)High Q110 HzFreq.Vib. AmplitudeLow Qrromkfπ21=Freq. Equation:Freq.StiffnessMassfo=8.5MHzQvac=8,000Qair~50μMechanical ResonatorPerformance:Lr=40.8μmmr~ 10-13kgWr=8μm, hr=2μmd=1000Å, VP=5VPress.=70mTorr[Bannon et al JSSC’00]C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06-100-98-96-94-92-90-88-86-841507.4 1507.6 1507.8 1508 1508.21.51-GHz, Q=11,555 Nanocrystalline Diamond Disk μMechanical Resonator• Impedance-mismatched stem for reduced anchor dissipation• Operated in the 2ndradial-contour mode• Q ~11,555 (vacuum); Q ~10,100 (air)• Below: 20 μm diameter diskPolysiliconElectrodeRPolysilicon Stem(Impedance Mismatchedto Diamond Disk)GroundPlaneCVD DiamondμMechanical DiskResonatorFrequency [MHz]Mixed Amplitude [dB]Design/Performance:R=10μm, t=2.2μm, d=800Å, VP=7Vfo=1.51 GHz (2ndmode), Q=11,555fo= 1.51 GHzQ = 11,555 (vac)Q = 10,100 (air)[Wang, Butler, Nguyen MEMS’04]Q = 10,100 (air)C. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06Radial-Contour Mode Disk ResonatorVPviInput ElectrodeOutput ElectrodeioωωοivoiQ ~10,000DiskSupporting StemSmaller mass Ö higher freq. range and lower series RxSmaller mass Ö higher freq. range and lower series Rx(e.g., mr= 10-13kg)(e.g., mr= 10-13kg)Young’s ModulusDensityMassStiffnessREmkfrro121⋅∝=ρπFrequency:RVPC(t)dtdCViPo=Note: If VP = 0V Ö device offNote: If VP = 0V Ö device offC. T.-C. Nguyen, “MEMS Technologies and Devices for Single-Chip RF Front-Ends,” CICMT’06, 4/25/06RF BPFRF BPFRF BPFMulti-Band Wireless HandsetsDuplexer90o0oA/DA/DRXRF ChannelSelect PLLIQLPFLPFRXRF LOIQAGCAGCLNADuplexerRF BPFLNAFrom TXLNALNARF BPFWCDMAWCDMACDMACDMA--20002000DCS 1800DCS 1800PCS 1900PCS 1900LNADuplexerLNARF BPFGSM 900GSM 900CDMACDMAFrom TXFrom