new power sources manufacturers association - specialty silicon … · 2018. 9. 11. · specialty...

© Copyright 2014-2017 CALY Technologies. All rights reserved. PROPRIETARY www.caly-technologies.com

CALY TechnologiesSpecialty Silicon Carbide (SiC) DevicesAdvanced Protection and Power Electronics

SAN ANTONIO – TEXAS , March 4-8, 2018

http://www.caly-technologies.com/

© Copyright 2014-2017 CALY Technologies. All rights reserved. PROPRIETARY 2

Reliability and Ruggedness : How to Address these

Challenges in Wide Bangap Semiconductor Devices

1- WBG DEVICE FAILURE MECHANISM

2 - CLASSICAL SOA APPROACH

3 - ADVANCED ELECTRO-THERMAL MODELING

APPLIED TO SiC Current Limiting Devices (CLD)

4 - CONCLUSION


WBG devices (tables typical failure mechanism versus device)


- HOW TO INSURE A HIGH RELIABILITY OF A WBG DEVICE ?

▪ Robust Device Design and fabrication

• Layout, fabrication process adaptation (metal, oxide, cleaning ..)

• Identification of SiC devices weaknesses : max. voltage & temperature range, critical

operating modes (SC, avalanche, cycling, latch-up…)

• Process and devices optimization

▪ Standard (JEDEC, AEC, MIL) and specific characterization, device burn-in

-> RECOMMENDATIONS TO END-USER (application notes)

BUT NOT ENOUGH !!!!

Electrical Application Engineers are always

pushing devices out of their specifications


SOA Diagram Limits• RDS(on) limit (orange line),

• Maximum current limit (magenta line),

• Maximum power and thermal instability

limit (black line)

• Breakdown voltage limit (green line).

The SOA diagram is determined for a constant case temperature of Tc=25°C and

various square-pulse width durations.

Not possible to get the device temperature in UIS for example.

Device paralleling mismatch not predictable


SOA Square-pulse determination generally does not

account for self heating

- The Safety Operation Area is a useful tool but not fully enable

predicting possible failures

- Need to add package temperature and device dynamic

electrothermal effects.

The proposed Electrothermal Spice model has been developed in

a view to estimate the maximal Channel temperature of a SiC

Current Limiting Device (CLD) in case of fast transients and long

overloads.


Current Limiting Devices

TYPICAL IV characteristic of a CLD (blue line) and a resistor (red line) Pulsed IV curve (tPULSE=200µs) for different TCASE.


Typical applications- e-fuse, current source, lightning protection : DC, AC, Pulsed

Lightning protection

Short-circuit / overcurrent protection

Overvoltage / surge protection

Capacitor pre-charging

Resettable fuse

Battery protections

DC general purpose protection applications

Unidirectional current limitation in AC or DC links

Photovoltaic power plant protection

Constant-current regulation for battery charging or LED driving

TYPICAL LIGHTNING PROTECTION

APPLICATION IMPLEMENTING SiC CLD


Current Limiting DevicesDynamic response to 1.2/50µs 1kV/500A pulse

-> Issue : power dissipation and temperature increase

-> How to estimate potential device failure ?

> Temperature estimation


Electro-thermal modeling

LEGEND


Electro-thermal modeling

CLD electro-thermal model circuit diagram


SiC CLD Isothermal Modeling

- ISOTHERMAL CHARACTERISATION

▪ Short square voltage pulses for wide temperature range

Isothermal CLD IV curves for different case temperatures ON-state resistance evolution with case temperature @ IDC=100mA


Packaging + Die Assembly Modeling

▪ Thermal impedance extraction

▪ RC network translation

Thermal impedance extraction procedure


Experimental Validation

- 1.2/50µs 900V/450A pulse,

Comparison of SiC CLD response to a 900V 1.2/50µs waveform.

INPUT PULSE VOLTAGE CLD CURRENT AVERAGE CHANNEL TEMPERATURE


CLD New SOA Representation

- From I=f(V,tPULSE) to V=f(TCASE,tPULSE) diagram

]

Maximal pulse voltage depending on :

- Case temperature

- Pulse duration (square pulse)

A CLD should be able to sustain Short-Circuit

Square pulses :

▪ VPULSE=200V ; tPULSE=100µs ; TCASE=125°C

▪ VPULSE=600V ; tPULSE=10µs ; TCASE=175°C

NEW SOA REPRESENTATION FOR SQUARE

PULSE (TO247 package)


Short-circuit pulse simulation

- VPULSE = 200V ; tPULSE=100µs ; TCASE=125°C

Simulated maximal temperature lower than 450°C

CLD SHOULD BE ABLE TO SUSTAIN SUCH A STRESS


Experimental validation : repetitive short circuit stress.

VPULSE=200V

TPULSE=100µs

TCASE=125°C

NO FAILURE AFTER 30 000 PULSES

50µs

I50us

Imax


Short-circuit pulse simulation

- VPULSE = 600V ; tPULSE=10µs ; TCASE=175°C

Simulated maximal temperature lower than 500°C


Experimental validation : repetitive short circuit stress.

NO FAILURE AFTER 83 000 PULSES

VPULSE=600V

TPULSE=10µs

TCASE=175°C


Failure prediction using SOA.

- VPULSE=600V; TCASE=175°C : 200µs < tFAILURE < 300µs

Simulated maximal temperature HIGHER THAN 780°C

METAL MELTING TEMPERATURE EXPECTED


Failure prediction using SOA.

- VPULSE=600V; TCASE=175°C : tFAILURE = 275µs

FAILURE AS PREDICTED BY SOA FOR 600V SQUARE PULSE

tFAILURE = 275µs


More Complex Simulations Possible

- DO160 CLASSIFICATION▪ W3 Level 3 : (600V/24A)

▪ W4 Level 4 : (750V/150A)

▪ W5 Level 4 : (750V/750A)

Simulated parameters :

Inrush current

CLD voltage

Channel temperature TCH

NO FAILURE if Channel temperature : TCH<600°C

Depends on device packaging (models for SMB, TO247 …)


An accurate device modeling has been carried out using Thermal

Finite Element and Spice simulation, for several packaging solutions.

This model has been experimentally validated using square pulses

and 1.2/50µs voltage surge waveforms (up to 1.2kV).

Repetitive short circuit stresses have also been performed on a group

of devices to corroborate the SOA diagram derived from this model.

USERS ABLE TO EVALUATE DEVICE PERFORMANCE IN AN

APPLICATION AND TO ESTIMATE MAXIMAL CHANNEL TEMPERATURE

AND KEEP VALUE BELOW MAXIMAL RECOMMENDED


Contact Us

http://caly-technologies.com/

mailto:[email protected]

new power sources manufacturers association - specialty silicon … · 2018. 9. 11. · specialty...

Documents