Maciej Sobocinski Eurosensors XXX

SIC MOSFET SOOT SENSOR IN A CO-FIRED LTCC PACKAGE.

Maciej Sobocinski, David Bilby, David Kubinski, Jaco Visser, Mike Andersson, Jari Juuti, Anita Lloyd Spetz, Heli Jantunen

Microelectronics Research Unit, Faculty of Information technology and electrical engineering, University of Oulu, FinlandDiv. of Appl. Sensor Science, IFM, Linköping University, SE-581 83 Linköping, Sweden

Ford Motor Company, 2101 Village Rd. Dearborn, MI 48121, USA

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maciej@ee.oulu.fi

SOOT• Impure carbon particles• size ranging from nm to 2.5 um• Result of incomplete combustion of

hydrocarbons• Many man-made and natural sources

including diesel engines• Believed to be 2nd biggest reason for

global warming• diesel exhaust ¼ total hazardous

pollution in the air• Linked to several adverse health effects

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HOW TO DEAL WITH SOOT IN CARS• Using the right fuel• PM filter

• Stops most of the soot (99%)• Needs regeneration mechanism• Prone to damage costly repairs

• PM sensors• Before and after PM filter• Notifies when to regenerate the filter

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CURRENT PM SENSORS FOR CARS• Differential pressure • Radio frequency• Accumulating • Electric charge

Bosh

Continental

Delphi

©Bosh

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SIC CHARGE BASED SOOT SENSOR

Flow

SiC

Floating gate

Source Drain

Gate insulator

Benefits of SiC• wide band gap semiconductor • ten times the electric breakdown field• two times the electron saturation

velocity • three times the thermal conductivity• high temperature and power electronics

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LOW TEMPERATURE CO-FIRED CERAMIC

Cornerstone of modern electronics Presented in the 80s of XX century Dielectric tapes and functional thick film pastes

Benefits of LTCC High conductivity, low loss conductors Fast prototyping Parallel processing Durable, hermetic, resistant Relatively cheap

©TDK-EPC

©IMSTBlanking Screen printing Laser shaping Stacking Laminating Sintering

SIC CHARGE SENSOR IN LTCC

• Floating gate SiC MOSFET sensors• Co-fired with LTCC• Hermetic encapsulation• No brazing/wire bonding/resin encapsulation• Suspended electrode to enhance deposition of

soot

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MEASUREMENT SETUP

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SOOT CAPTURING MECHANISM

10SENSOR RESPONSE WITH ELECTROPHORETIC SOOT CAPTURING

AND WITHOUT

11SENSOR RESPONSE WITH HIGHER ELECTROPHORETIC VOLTAGE

Soot accumulation distorts the response

12SENSOR RESPONSE WITH HIGHER ELECTROPHORETIC VOLTAGE

Soot accumulation distorts the response

13INFLUENCE OF SOOT ACCUMULATION ON SENSOR OUTPUT

Clean Stuck with soot

Need for sensor regeneration!

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RESPONSE TO DIFFERENT CONCENTRATIONS

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CONCLUSIONS

• Floating gate SiC transistor can be used to detect soot• External electric field across the collection channel

increases speed of soot capturing• The electrophoretic voltage has its optimum [160 V

across 500 um gap in this case]• Sensor accumulates soot which mutes the response –

need for regeneration• Fast responses, dependent on concertation available at

the right conditions• Combination of SiC and LTCC allows placing of the sensor

directly in exhaust lines of diesel engines

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THANK YOU FOR YOUR ATTENTION

SENSORS - INTEGRATION THROUGH CO-FIRING

bulk insertion

Lamination:– 75 º C– 10 MPa

pressureCo-firing:

– 865 º C– 30’ in peak T