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Study of MEMS Devices for Space Applications ～Study Status and Subject of RF-MEMS～

The 26th Microelectronics Workshop October, 2013

Maya Kato Electronic Devices and Materials Group Japan Aerospace Exploration Agency

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Outline

Introduction Surrounding applications Space applications RF-MEMS - What is RF-MEMS?

- Advantage of RF-MEMS switches - Comparison of RF-MEMS switches and other switches - Variation - Applications - Evaluation of commercial switches - In-house research and development - Subject

Conclusions

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Introduction

■MEMS: Micro Electro Mechanical System The technology of very small devices using a microfabrication technique. ■Advantages of MEMS Devices

– Downsizing and weight saving ・ For microfabrication applied by a semiconductor process ・ To integrate structure and electronic circuits

– High functionality ・ To implement various functions on one-chip. – Low cost and stable production

・ Similar to the semiconductor process, MEMS can be mass-produced with good and stable quality

Laser radar (distance control)

Acceleration sensor （airbag）

Microphone （ communication ）

Gyroscope （position control ）

Pressure sensor （tire pressure ）

Pressure sensor (engine control)

Environment sensor （ temperture and humidity control）

Surrounding applications

■ MEMS applications - Accelerometers : airbag system, game controller, cell phone - gyroscopes : car navigation system, digital camera - inkjet heads : inkjet printers - Bio-MEMS : Lab-On-Chip

Microphone

Gyroscope, Acceleration sensor (display, games)

inkjet heads

MEMS ＝ ＋ Integrated circuit

Space application

・Small and lightweight ・Power saving

Si chip

Sensor

RF

RF

Micro dynamo

Circuit

・High-density ・High-performance

System downsizing → More system redundancy → More space for mission system

Wireless test system (reject the test harnesses)

New Device

Monitoring of cabin environment and health of astronaut

RF-MEMS

RF-MEMS ： Radio Frequency Micro-Electro-Mechanical-Systems For example・・・

Phased-array antenna ： ・ Several thousand radiating elements required ・ Complex subsystem is high cost

Switch matrices： ・Hundreds of switches required ・Bulky and heavy

✓Small size ✓ Lightweight ✓ Excellent RF performance ✓ Low insertion loss ✓ High isolation ✓ Low power consumption ✓ Low cost ✓ New architecture

Large impact !

Switch matrices1 Phased Array type L-band Synthetic. Aperture Radar

1Mojgan Daneshmand, “Multi-Port RF MEMS Switches and Switch Matrices”, University of Waterloo, Ontario, Canada, 2006

■What is RF-MEMS? Radio frequency applications using MEMS.

RF-MEMS are expected to provide multiband and low power consumption and downsizing.

For example ・・・ Characteristics Applications

Switch Low loss High isolation

Multiband by switching circuit construction

Varactor High variability High linearity

Wide bandwidth of oscillator circuit, amplifier circuit and matching circuits

Inductor High Q factor Variable

inductance

Low power consumption of oscillator circuit and amplifier circuits

Resonator High Q factor downsizing

Downsizing and integration of oscillator circuit and filter

Charactristic and application of RF-MEMS

RF-MEMS

■Advantage of RF-MEMS switch

By replacing the current space components with RF-MEMS switches, the system of satellite reduce size and weight.

Surface-micromachined devices using mechanical Movements to open and close circuits in the RF transmission-line

・Very low insertion-loss ・Very high isolation

Power consumption is nearly zero using electrostatic actuator and piezoelectric actuator.

RF-MEMS

Advantage of RF-MEMS ・Small size ・Low power condumption ・Excellent RF performance

■Comparison of RF-MEMS switches and other switches. Semiconductor Conventional

mechanical MEMS

PIN FET

Range MHz～ DC～ DC～GHz DC～GHz Size Small

[1/100-1/1000] Small

[1/100-1/1000] Large

[1] Small

[1/100-1/1000]

Voltage (V) 3-5 3-5 5-30 3-80

Power consumption (mW) (during latch state)

10 ≈ 0 ≈ 0 ≈ 0

Switching speed 1-100 ns 1-100 ns 10-50 ms 1-300 μs

Isolation Medium Low High High

Insertion loss Medium High Low Low

Power handling (W) Small Small Large Small

Switch type Parameter

RF-MEMS

■Variation CONDUCTIVE TYPE Contact type ：

Capacitance type ：

DC～GHz, good property (～30GHz), high isolation, low insertion loss, possible failure mode―corrosion, stiction GHz, good property (20-100GHz), possible failure mode―dielectric charging

DRIVE SYSTEM Electrostatic actuation : Piezoelectric actuation : Magnetic actuation・heat transfer actuation :

low power consumption, high actuation voltage, simple to fabricate low power consumption, low actuation voltage

low actuation voltage, consumes significant power（＞mA）

SWITCH ARCHITECTURE Series type : Shunt type :

Switches are connected in series ON ： close, OFF ： open Switches are connected in parallel ON ： open, OFF ： close

We should select the most appropriate RF-MEMS switch. Failure mode analysis and reliability tests are required in each case.

RF-MEMS

■Applications Redundant and reconfigurable switch matrices

Conventional switch matrices1

Requirements specification ■ Cycles ： million ■ Transmission power ： ～ tens of W ■ Switching speed ： < sec ■ Lifetime ： ～15 years

Phase shifters of phased array antenna for satellite communication and radar systems

Requirements specification ■ Cycle ： billion ■ Transmission power ： ～ tens of W ■ Switching speed ： < μsec ■ Lifetime ： ～15 years

By applying RF-MEMS switches to phase shifters for satellite communication and radar systems, we can achieve high performance, size reduction, and low power consumption. Especially RF-MEMS switches have excellent RF performance relative to semiconductor switches.

Phased Array type L-band Synthetic. Aperture Radar

Since satellite communication system have hundreds of switches integrated in the form of switch matrices to provide system redundancy, any reduction in size and mass would have a significant overall impact. Furthermore, It is expected to realize more advanced redundant systems.

1Mojgan Daneshmand, “Multi-Port RF MEMS Switches and Switch Matrices”, University of Waterloo, Ontario, Canada, 2006

RF-MEMS

Evaluation of commercial switches

RF-MEMS

■Evaluation of commercial switches

RF-MEMS

Selected samples ■ Omron Corp. in JAPAN ■ Advantest. in JAPAN

Contact point

Movable electrode The Omron switch is a electrostatically-actuated single-pole double-throw (SPDT) switch released in 2008, the performance of which has been highly praised by researchers from around the world.

The Advantest switch is a piezoelectric SPDT switch driven by PZT, which is expected to be used for high-speed LSI test system. The advantage is high RF performance at 20 GHz.

Contact point Movable electrode

We would like to thank Omron Corp. and Advantest for assistance in the evaluation of switches.

■Evaluation of commercial switches We conducted some environmental tests on Omron and Advantest switches.

Test title Test condition Omron (2SMES-01)

Advantest (PMD1+LTCC)

Mechanical shock 1,500g(peak), Duration of pulse 0.5msec, +X,-X,+Y,-Y,+Z,-Z (for each three times)

0/3 0/3

Random vibration Overall rms 34.02G, 15minutes, X,Y,Z

0/3 0/3

Vibration, high frequency

20g(peak), 10～2,000Hz, Sweep time 20min, X,Y,Z

0/3 0/3

Thermal shock -55～+125℃, 100cyc ※We are going to add a cycle until it breaks down.

0/4 0/4

Failure; Change in contact resistance level exceeding 1000mΩ

RF-MEMS

Specialized switches for space

RF-MEMS

■In-house research and development To further enhance performance and reliability, we fabricate and evaluate RF-MEMS switches.

Cross-sectional view of a metal-contact switch.

Switch type ： Metal-contact switch The switch was originally designed by Mitsubishi Electric. Their switches were successfully launched and demonstrated in space as a first in Japan.

Range ： ～40GHz Insertion loss ： < 0.3dB Switching time： 10 μsec Cycles ：10 billion

Target

RF-MEMS

We appreciate the help received from Dr. Sang-Seok Lee from Tottori University with valuable discussion and assistance in fabrication.

Metal contact RF in

RF out

Cantilever

Actuation electrode

■Subject

Power handling for transmit signals The transmission power within satellites can be very high, due to the need to overcome long transmission paths.

Long-term system reliability Satellite systems must operate for more than 10 years ,without failing. ・Number of switching cycles ・ Life time

Reliability tests for space applications are needed. ・Radiation ・Thermal cycling ・Thermal shocks ・Vibration and mechanical shock ・Operation in very high vacuum

Space-specific reliability

We need to establish an accelerated test method.

RF-MEMS

Establish the test method

We confirmed positive results.

Earch failure mode analysis There are various types of switches by the conduction systems, and the drive systems, and switch architecture.

Other approaches

Other approaches

■MEMS mirror ECO SCAN ESS214A （The Nippon Signal Co., Ltd.） Vibration test ：30G

■MEMS shutter We fabricate a MEMS shutter for irradiation tests of electric devices

Other approach

■TAG202(Tamagawa Seiki Co.,Ltd.)： Tuning-fork type vibration gyro using LiNbO3 oscillator.

○Temperature cycling test －40 ～ ＋125℃, 30min, 2000 cyc ○Vibration test 20～2kHz, 20G, x,y,z ○Sealing test

No change in the basic property

detection drive

○Mechanical shock 1000G, (half-sine ), x､y､z ○High Temperature Operating test 85℃, 4000h

TAG 234 will be used as a data source for SOFIE SOFIE ＝ SOI-FPGA In-orbit demonstration Equipment

■MEMS gyro ■MEMS mirror

■ ECO SCAN ESS214A （The Nippon Signal Co., Ltd.） : Electromagnetic drive type mirror.

○ Mechanical shock 644G，1msec，xyz ○Vibration test 30 G

Other approach

■MEMS shutter

Test Sample

Light / Radiation Shutter cover Actuator

Target area

For irradiation tests on electric devices, we fabricate a MEMS shutter which can control the irradiation area according to the aperture. The purpose is a reduction of the time and expenses required in irradiation tests.

■QCM (Quartz Crystal Microbalance) QCM is a mass sensor, which can be used to monitor of spacecraft, but the temperature compensation type is expensive and inflexible. We therefor fabricate the original QCM sensor. Target performance

- Temperature: LN2(-196 ˚C) to 100˚C - Mass Sensitivity: picogram to nanogram

Conclusions MEMS devices are expected to be applicable to space systems owing to their significant advantages.

Advantage ✓Small size ✓ Lightweight ✓ Low power consumption ✓ Excellent RF performance ( low insertion loss, high isolation ) ✓ Low cost

To investigate the feasibility of RF-MEMS switches for the space applications, we have performed durability experiments.

To improve reliability and performance, we fabricate RF-MEMS switches.

Evaluation of commercial switches

In-house research and development

Application ・Redundant and reconfigurable switch matrices ・Phase shifters of phased array antenna for satellite communication and radar system

RF-MEMS switches are expected to be particularly applicable to space systems.

Subject ・Earch failure mode analysis ・Long-term system reliability ・Power handling for transmission signals ・Space-specific reliability ・Establish the tast method

・ Study the failure mechanism and reliability ・ Enhanced performance and reliability for space applications

Future ：

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Thank you for your attention