Micro Electro Mechanical System

Transcription

1 Micro Electro Mechanical System Jung-Mu Kim

2 Mechatronics Mechatronics -The combination of mechanical engineering, electronic engineering and software engineering. Purpose of this interdisciplinary engineering field -The study of automata from an engineering perspective and serves the purposes of controlling advanced hybrid systems. [WIKIPEDIA] 2 / 44

3 What is MEMS? Micro Electro Mechanical System Innerspace movie (1987) Sandia National Lab., USA 3 / 44

4 MEMS Products DMD [Texas Instrument] Optical MEMS Scanner [Microvision] Micro system Sensors Actuators RF MEMS RF MEMS switch [Teravicta] RF MEMS switch [RadantMEMS] Inertial sensor MEMS accelerometer & gyroscope [Analog Device] Resonator [SiTime] Resonator, Microphone MEMS microphone [Knowles] 4 / 44

5 Micro Robots A Robot is a mechanical or virtual, artificial agent. It is usually an electromechanical system, which, by its appearance or movements, conveys a sense that it has intent or agency of its own. [WIKIPEDIA] Micro-Robot [Dartmouth] MEMS Robot Bugs [DARPA] Bloodstream Robot [Technion Univ.] Cyborg Beetle [UoM] MEMS endoscope [Draper Lab.] Tadpole robot [KIST] 5 / 44

6 MEMS market 6 / 44

7 Micromirror Applications Benefits of micromirrors as optical devices - Direct handling of light - Large scalability - Simple electronics Micromirror applications -Display - Scanners - Optical cross connects (OXCs) - Variable optical attenuators (VOAs) - Tunable filters - Spatial light modulators (SLMs) DMD TM by Texas Instruments Optical scanner by U.C.Berkeley Grating Light Valve (GLV) by Silicon Light Machines Optical crossconnects (OXC) by Lucent Technology 7 / 44

8 Single crystalline silicon (SCS) mirrors Multi layered SOI by Analog Device SOI anodic bonded mirror by C. H. Mastrangelo et al. High voltage circuitry integrated mirrors by Transparentnetworks Self alignment bonded mirror plate by U. C. Berkely SOI wafer adhesive bonding by Lucent Technology SOI wafer adhesive bonding by J. Haasl et al. 8 / 44

9 Micromirror Array for Projector Mirror post Torsional spring Mirror plate screen in out screen out screen inout V off onv V off on V onv off V off onv V off on 9 / 44

10 Projection System using Micromirror Array From IEEE Spectrum 10 / 44

11 Fabricated Micro Mirror Array From T.I. 11 / 44

12 Micro Mirror Array for Display Mirror Plate Spring Hinge Girder Addressing Electrode From Samsung Electronics 12 / 44

13 Promising optical MEMS Texas Instrument s cell phone projector Microvision s pico projector display 13 / 44

14 MEMS inkjet head 14 / 44

15 MEMS inkjet head 15 / 44

16 MEMS inkjet head 16 / 44

17 MEMS inkjet head 17 / 44

18 MEMS Inertial Measurement Units Application of of gyroscope -Inertial Navigation System System -GPS -GPS -Suspension operation of of cars cars -Compensation of of movement of of the the hands hands for for camcorder -Self-operation of of robots robots -Head -Head Mounted Display(HMDS) -Night -Night Vision Vision Goggle(NVG) -Flight -Flight simulator 18 / 44

19 Decoupled In-planar(DIP) Vibratory Gyroscope Drive mode Angular rate Detection mode Drive mode Detection mode Coupled vibratory gyroscope Elliptical motion Decoupled vibratory gyroscope Laterally flexible suspension structure In-plane driven(x) and sensed(y) mode Angular rate input z axis 19 / 44

20 DIP Vibratory Gyroscope No operation Ω Y X Drive mode Angular rate input Operation schematics Vector product Y Ω X Detection mode 20 / 44

21 Microgyroscope Structure Driven mode flexure Fixed anchor Inner gimbal Sensed mode flexure Outer gimbal Sensed electrode(+) Sensed electrode(-) Rebalancing electrode Balancing electrode Comb drive Schematics of in-plane vibratory gimbaled microgyroscope 21 / 44

22 Microgyroscope Structure Inner gimbal Driven mode flexure Fixed anchor Sensed mode flexure Sensed electrode(+) Sensed electrode(-) Tuning electrode Vibrating gyroscope: Coriolis accelleration Capacitive driving and sensing Stability: 4 degrees per hour Sensed mode Outer gimbal Comb drive Rebalancing electrode Angular rate Driven mode 22 / 44

23 Fabrication Result Cavity Detection electrodes Anchor Glass cap Drive electrodes Detection spring Drive spring Rebalance electrodes Wire bonding Ceramic package Fabricated gyroscope Sealing and ceramic package 23 / 44

24 Electrostatically driven and Capacitively sensed Angular Rate Sensor - ECARS Simple fabrication process : Single photolithography and single etch process Comb type driving and sensing electrodes : Small air damping effect Good linearity Large inertial mass Large spring stiffness : Stiction free High resonant frequencies Good electrical isolation by glass substrate Rotor Stator Glass substrate Inner folded beam springs : Mechanically decoupled Large gap for small air damping effect 24 / 44

25 Fabrication Results Inertial mass Stopper Gimbal Sensing springs Driving springs Driving electrodes Tuning electrodes Sensing electrodes 25 / 44

26 Experimental Setup Function generator DC power supply Driving and sensing circuit Oscilloscope Output Spectrum analyzer 26 / 44

27 Why RF MEMS? Demand on higher frequency sources AM & FM Below MHz 88~108 MHz Cellular & PCS phones 800 MHz~2 GHz Satellite & radar ~20 GHz LMDS ~30 GHz WLAN, Automotive application ~70 GHz Requirements for for the the high high frequency communication systems Multiple Multiple functionality functionality Multiple Multiple transmitters transmitters and and receivers receivers on on the the same same platform platform Low Low power power consumption consumption Linearity: Linearity: low low inter-modulation inter-modulation distortion distortion High High degree degree of of frequency frequency agility agility Narrow Narrow band band filtering filtering Limited performances of the solid-state devices RF MEMS!!! 1 27 / 44

28 Advantages of RF MEMS Improvement of the power efficiency - Replace solid state circuit with a single micromechanical component on size scales Simply integrated with conventional IC s Replace discrete, off-chip components (switch, varactor, inductor) with micromachnined elements Monolithic integration is possible. Reduction of the fabrication cost, size, and complexity Batch fabrication 1 28 / 44

29 MEMS Devices in RF Antenna 1Antenna 2 Antenna Switch Bandpass Fliter (ceramic ) TFR or micro mech./ micromachin. resonator Micro mech. resonator Micro mech. switch Off-Chip Passive Elements On-chip micro mech. inductor + tunable capacitor Image IF Filter Reject Filter (SAW) (ceramic) TFR micro mech./ or micromachin. resonator Low loss transmission lines Power Amplifier Transmitter Micro mech. resonator Micro IF LNA mech. switch RF LNA Mixer T/R Inductors VCO and variable capacitors AGC switch RF Xstal filterschannel IF PLL Tank Select PLL Micro mech. RF MEMS switches resonator Modulator Micro mech. resonator IF Mixer VCOs (Voltage-controlled oscillators) Phase shifters Movable antennas Transmit PLL Receiver Micro mech. resonator On-chip inductor + micro mech. tunable capacitor System-level schematic detailing the front-end design for a typical wireless transceiver. VCO Xstal Tank DAC DAC ADC ADC From Clark T.-C. Nguyen 29 / 44 I I Q Q

30 Fabricated Transmission Lines Signal line 3 Conventional CPW 2.65 db/cm Ground line Fabricated ECPW line Loss (db/cm) 2 1 ECPW 1.9 db/cm 1.25 db/cm OCPW 15 μm Signal line Ground plate 3.3 μm Frequency (GHz) Measured responses of the 40 ohm-lines (Glass substrate) Fabricated OCPW line From Lab. for MiSA, SNU 30 / 44

31 Micromachined High-Q Inductors Application : Filters, oscillators, low-power converters Quality factor Q and self-resonance frequency are the important factors. Q factor is dependent on the resistive metal lines and dielectric losses in the substrate turn Al spiral inductor - Q = 5 at 1 GHz, 127 nh From UCLA - 3-D, Cu line with Ni sacrificial layer - Q = 38 at 1.8 GHz, 14 nh From KAIST - High Q micromachined inductor ( Q = 30) From of Michigan 31 / 44

32 Area Tuning Tunable Capacitors From Rockwell Science Center 32 / 44

33 Gap Tuning Tunable Capacitors Application : LNA(Low Noise Amplifier), harmonic frequency generator, VCO(Voltage Controlled Oscillator) Tuning ratio is an important factor. Electrothermal From of Colorado SDA Direct electrostatic From UC Berkeley Indirect electrostatic (scratch drive actuator) From of Hawaii 33 / 44

34 Tunable Filter using Tunable Capacitor Micromachined variable capacitor DC bias source RF choke Micromachined variable capacitor Half λ line Port 1 Port 2 Topology of two-pole resonators filter Using 2-pole resonators Frequency shift with micromachined variable capacitors connected to half wavelength resonators 6.2% center frequency shift from 30.6 GHz to 28.7 GHz From Lab. for MiSA, SNU 34 / 44

35 Fabrication and Measurement Tunable Filter Variable capacitors 200 μm ⅹ200 μm Dielectric layer Cantilever beam S 21 (db) d gap = 6 μm d gap = 5 μm 10 d gap = 4 μm 0-10 S 11 (db) Port λ/4 stub Frequency (GHz) DC pad DC bias line Port1 Measured filter characteristics From Lab. for MiSA, SNU 35 / 44

36 Types of MEMS Switches Capacitive shunt switch Direct contact series switch Input Dielectric layer OFF Input Normally OFF Normally ON Output ON Output Capacitive shunt switch OFF state with capacitive coupling Isolation dependent on capacitive ratio between ON and OFF state Longer contact lifetime Not suitable for low-frequency applications Direct contact series switch ON state with metal-to-metal ohmic contact Insertion loss dependent on the contact resistance Broad frequency coverage Short contact lifetime 36 / 44

37 RF MEMS phase shifter In Air-gap overlay 3-dB CPW couplers Out 3-dB coupler MIM C 1 capacitor array C 2 capacitor array C 11 C 12 C 13 C 14 C 21 C 22 C 23 C 24 C 0 C 0 C 0 C 0 C 0 C 0 C 0 C 0 MAM (C 1 ) MAM (C 2 ) Bias ports Bias ports Topology for 2-stage reflection-type phase shifter 37 / 44

38 RF MEMS phase shifter Number of pull-in state capacitor = Relative phase shift [deg] Insertion loss [db] Return loss [db] Frequency [GHz] Frequency [GHz] Frequency : 5 ~ 17 GHz (wide bandwidth) Average insertion loss : 3.48 db over 5 ~ 17 GHz (very low loss) Maximum phase error : ± 2.8 Actuation voltage : 25 V 38 / 44

39 RF MEMS antenna Patch antenna Vertical axis Horizontal axis MMIC DC bias line 1.5 cm 1.5 cm RF MEMS antenna after mounting of MMIC and release process 39 / 44

40 RF MEMS antenna Relative antenna gain [db] tilt -9 tilt 0 tilt 9 tilt 18 tilt Relative antenna gain [db] tilt 0 tilt 9 tilt Angle [deg] Angle [deg] Measured radiation pattern when the moving plate rotates along the vertical axis (-18 ~ 18 ) Measured radiation pattern when the moving plate rotates along the horizontal axis (-9 ~ 9 ) 40 / 44

41 RF MEMS packaging RF input Silver via G S Contact pad (gold) LTCC G G S G RF output LTCC Screen printed silver epoxy CPW (gold) Quartz Quartz RF MEMS packaging using LTCC substrate and silver epoxy CPW BCB 41 / 44

42 Research in Lab. For MiSA Optical MEMS Micro Gyroscope Driving comb electrodes Sensing electrodes Inertial mass Sensing comb electrodes Driving comb electrodes 42 / 44

43 Research in Lab. For MiSA Bio MEMS RF MEMS Signal line Signal line Ground Ground 43 / 44

44 Research in Lab. For MiSA Silicon spring SMA connector MEMS switch Spiral inductor Contact part Jig MEMS probe Silicon switch Tunable filer for WLAN Micromachined probe for permittivity measurement Via post shape Cavity depth CPW design input 3 mm output 3 mm Packaged CPW 44 / 44