RF MEMS at EADS: Concept, Designs, and Applications

Transkript

1 EA D S INNOVA TION W ORKS RF MEMS at EADS: Concept, Designs, and Applications Dr. Bernhard Schönlinner Dr. Bernhard Schönlinner, EADS Innovation Works Germany, , bernhard.schoenlinner@eads.net 1

2 EADS Airbus Military Transport Aircraft Eurocopter Space Defence & Security Systems Tom Enders Francisco Fernández-Sáinz Lutz Bertling François Auque Stefan Zoller EADS Innovation Works Dr. Bernhard Schönlinner, EADS-IW-SI, , 2

3 Content RF MEMS: Mode of operation Temperature stability Charging of dielectric layers Power handling Achieved performance at EADS RF MEMS designs and results at EADS RF MEMS applications at EADS Dr. Bernhard Schönlinner, EADS-IW-SI, , 3

4 RF MEMS Switches 2 types of RF MEMS switches: ohmic switches capacitive switches Most popular actuation mechanism: electro-static ohmic switch capacitive switch Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 4

5 Mode of Operation Default state: cantilever in the up-state Apply DC-voltage between cantilever and pull-down electrode Electrostatic forces pull cantilever to down-state 2 µm 0.2 µm up-state Cantilever down-state Insulation layer Pull-down electrode Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 5

6 Mode of Operation Similar mode of operation as cantilevers 300 µm 0.8 µm 2 µm 0.2 µm down-state Insulation layer Membrane up-state Pull-down electrode Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 6

7 Photographs of Different Designs Fixed-fixed membrane designs Dr. Bernhard Schönlinner, EADS-IW-SI, , 7

8 Photographs of Different Designs Cantilever designs Dr. Bernhard Schönlinner, EADS-IW-SI, , 8

9 EADS Approach for RF MEMS Substrate: high-resistivity Silicon 200 nm of thermally grown Silicon oxide Metal cantilever with intrinsic stress curls up Backside metallisation Implantation zone for capacitive coupling Metallisation Silicon Silicon oxid Ion implantation (conductive) Dr. Bernhard Schönlinner, EADS-IW-SI, , 9

10 MEMS Issues Macro-World Micro-World Gravitational force Vibration Acceleration Fatigue Temperature Electrostatic charges Humidity - stiction of surfaces Dust Thermal management Temperature Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 10

11 Temperature Stability Thermal expansion: stress! Membrane buckles Cannot operate anymore Dr. Bernhard Schönlinner, EADS-IW-SI, , 11

12 Temperature Stability Design approaches: Cantilever design Thermal decoupling through anchor design Dr. Bernhard Schönlinner, EADS-IW-SI, , 12

13 Charging of Dielectric Layer High electric fields across insulation layer Charges are driven into insulation layer Charges stay there and hold membrane in down-state Depends on the quality of the insulation layer!! Dr. Bernhard Schönlinner, EADS-IW-SI, , 13

14 Charging of Dielectric Layer Design approaches: Omit insulation layer possible for ohmic switches capacitive switches: little down-state capacitance up-state down-state Dr. Bernhard Schönlinner, EADS-IW-SI, , 14

15 Charging of Dielectric Layer Design approach: Use good dielectric: thermally grown Silicon oxid easy to fabricate well characterised highly reproducible Metallisation Silicon Silicon oxid Ion implantation (conductive) Dr. Bernhard Schönlinner, EADS-IW-SI, , 15

16 Power Handling ( Hot Switching ) Main challange for ohmic switches: Micro-welding typically: max power 1 mw Main challange for capacitive switches: Self-actuation typically: max power < 500 mw Micro-welding Self-actuation or hold-down Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 16

17 Power Handling ( Hot Switching ) Design approach: Avoiding the pull-in effect Typically: pull-down voltage of 30 V -> hold-down voltage of V Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 17

18 Power Handling ( Hot Switching ) Curled cantilever: Pull-down voltage: 30 V Hold-down voltage: 25 V -> high restoring force -> less prone to self-actuation Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 18

19 Reliability of EADS RF MEMS Switching cycles 10 9 switching cycles performed with no change in performance Temperature of operation No degradation after operation for 40h at 120 C Power handling >6W measured in hot switching mode Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 19

20 Movie Dr. Bernhard Schönlinner, EADS-IW-SI, , 20

21 EADS RF MEMS Circuit Designs Switches Phase shifters Tunable filters and antennas Dr. Bernhard Schönlinner, EADS-IW-SI, , 21

22 Switches for Ku- to Ka-band 0 Ku-band Microstrip Series Switch 0 S21 up-state in db S21 down-state in db Frequency (GHz) 12GHz IL = - 0.2dB IS = - 17dB Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 22

23 High-isolation Ka-Band switch 0 0,0 Carbon line DC pad S 21 up-state [db] ,5-1,0-1,5-2,0 S 21 down-state [db] IL = - 0.5dB IS = - 35dB Frequency [GHz] S 21 up-state (measurement) S 21 up-state (simulation) S 21 down-state (measurement) S 21 down-state (simulation) -3, Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 23

24 SP4T Ku-Band switch S11 and Isolation (db) Insertion Loss (db) Frequency 12GHz IL = - 0.4dB IS = - 22dB Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 24

25 EADS RF MEMS Circuit Designs Switches Phase shifters Tunable filters and antennas input output Direction of antenna beam Phase front RF signal progressive phase delay Dr. Bernhard Schönlinner, EADS-IW-SI, , 25

26 3-bit transmit phase shifter at Ka-band Miniaturized 180 -Bit and novel 45 Phase deviation = < Mean Insertion loss = < -2.2dB Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 26

27 EADS RF MEMS Circuit Designs Switches Phase shifters Tunable filters and antennas Dr. Bernhard Schönlinner, EADS-IW-SI, , 27

28 RF-MEMS switchable patch antenna in Ka-band 0 Insert feed depth 370um S11 in db up state down state Sim_Patch_up Sim_Patch_down Frequency (GHz) Released area Anchor points Si Oxide f = 3.1GHz BW = 0.8Ghz down-state 1GHz up-state S11 > -1.7dB in operational range of the other state filter function Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 28

29 RF-MEMS switchable filter in Ka-band 0-5 S21 in db pole microstrip ladder filter 300 µm of the resonators are switchable Frequency (GHz) Dr. Bernhard Schönlinner, EADS-IW-SI, , Sim_down Sim_up Meas MF3 down Meas MF3 up 80V Frequency shift: 20% (80 V) Insertion loss: -1.5 db (down) -1.7 db (up) -3 db bandwidth : 16% (down) 15% (up) Ripple in passband: 1.1 db

30 Applications of RF MEMS Circuits Electronically steerable antennas for communication Electronically steerable antennas for radar Multi-band communication and electronic counter measures Dr. Bernhard Schönlinner, EADS-IW-SI, , 30

31 Electronically steerable antennas: for communication Scenario: Bi-directional broadband SatCom links from a mobile platform to a satellite and vice-versa Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 31

32 Electronically steerable antennas: for radar Scenario: Enhanced onboard airborne sensor systems Dr. Bernhard Schönlinner, EADS-IW-SI, , 32

33 Multi-band communication and ECM Scenario: Next generation multi-band satellite payloads, airborne radar and ECM systems Dr. Bernhard Schönlinner, EADS-IW-SI, , 33

34 Summary Microsystems are a class of devices that find more and more access into our daily life RF MEMS switches are one example with a wide range of possible applications e.g. in aerospace Advantages are obvious Challenges still exist It is a question of time when they will be applied in many products Dr. Bernhard Schönlinner, EADS-IW-SI, , bernhard.schoenlinner@eads.net 34

35 Thank you! Dr. Bernhard Schönlinner, EADS-IW-SI, , 35