next generation sic mosfets performance and …neil/sic_workshop/presentations...2 • the wolfspeed...

Next Generation SiC MOSFETsPerformance and Reliability

A CREE COMPANY © 2016 Cree, Inc. All rights reserved

Brett Hull , Dan Lichtenwalner, Sei-Hyung Ryu,Edward van Brunt, Jon Zhang, Scott Allen, DaveGrider, Jeff Casady, Al Burk, Michael O’Loughlin,John PalmourAugust 18, 2016

Performance and Reliability

ARL MOS Workshop - August 18, 2016

2

• The Wolfspeed division to be acquired includes:- The Power and RF device business- The SiC substrate business for Power, RF and

gemstone applications

• The LED portion of Cree’s Materials business willremain part of Cree

INFINEON TO ACQUIRE WOLFSPEED

© 2016 Cree, Inc. All rights reserved 2

• We remain and operate as separate companies untilthe transaction closes

• It is business as usual for us until the transaction closes

• The transaction is subject to US Government regulatory approval and is expected toclose within calendar year 2016.

ACKNOWLEDGEMENTS

Sponsored in part by Army Research Laboratory under CooperativeAgreement W911NF-12-2-0064


The information, data, or work presented herein was funded in part bythe Office of Energy Efficiency and Renewable Energy (EERE),

U.S. Department of Energy, under Award # DE-EE0006920.Stephen Boyd and Charles Alsup monitors.

OUTLINE

• Wolfspeed SiC MOSFET Product Portfolio— Design principles and evolution of device generations

• Introduction to Trench MOSFETs for next generation

• Performance and Reliability


• Performance and Reliability— 900V/10 mW Gen 3 MOSFETs— Intrinsic Failure Mode High Voltage and Gate Lifetime Estimates— Gate Qualifications and Attempting to Predict Early Failures

• Summary

MOSFET RESISTANCECell Pitch

Subs

Drift

DriftSpreading

Spreading

JFET

JFET

Ohmic

Ohmic

MOS chan

MOS chan

20%

40%

60%

80%

100%

Res

isti

veC

omp

onen

t%

Resistive Components


• Channel resistance is a significant portion of resistance in lower voltage products

• Cell pitch drives channel packing density – the higher the channel density, the lower the totalchannel resistance (Rch)

• Proper Engineering of the JFET gap reduces JFET resistance (RJFET) while improving theshielding of the gate oxide

SubsSubs0%

Gen3 1200 V 10 kV

SPECIFIC ON-RESISTANCE AND BREAKDOWN VOLTAGE

10

100

(mc

m2)

15 kV

10 kV

6.5 kV

3.3 kVCree CMF Family

•

• Achieved the limit for 3.3 kV andhigher SiC DMOSFETs

• Gains remain to be had for lowervoltage SiC DMOSFET products


1

10

100 1,000 10,000

RO

N,S

P

Breakdown Voltage (V)

3.3 kV

Cree C2M Family

Cree CMF Family voltage SiC DMOSFET products– Increase channel density– Increase channel mobility

4

6

8

10

12

Spec

ific

On

Res

ista

nce

(mW

cm2 ) 25°C

150°C

1200V PLANAR MOSFET ON-RESISTANCE EVOLUTION

0.8X

Gen

1

0.5X

Gen

1© 2016 Cree, Inc. All rights reserved 7

0

2

4

Gen 1 - Planar (2011Product)

Gen 2 - Planar (2013Product)

Gen 3 - Planar (2016R&D)

Spec

ific

On

Res

ista

nce

(m

Optimized Epitaxy, reducedcell pitch, cell engineering

0.5X

Gen

1

TRENCH MOSFET – INCREASED CHANNEL DENSITY

N+ 4H-SiC substrate

P-WellP-Well

N+ N+

Source Source

Aluminum

Poly-Si Gate

Intermetal Dielectric

Gate Oxide

Drain

4H-SiC n- Epitaxial Layer

Cell Pitch Planar MOSFET

2

4

6

8

10

12

Sp

eci

fic

On

Re

sist

an

ce(m

Wcm

2 ) 25°C

150°CReaching

practical limits


N+ 4H-SiC substrate

Source Source

Aluminum

Intermetal Dielectric

Drain

4H-SiC n- Epitaxial Layer

P-Well

N+

P-Well

N+Poly-SiGate

Gate

Oxid

e

Cell Pitch

Trench MOSFET

Must demonstrate equivalent orbetter reliability in going from

Planar to Trench geometry

0

Gen 1 - Planar(2011 Product)

Gen 2 - Planar(2013 Product)

Gen 3 - Planar(2016 R&D)

Gen 4 - Trench(Est)

Sp

eci

fic

On

Re

sist

an

ce(m

PERFORMANCE AND RELIABILITY UPDATE

© 2016 Cree, Inc. All rights reservedA CREE COMPANY

PERFORMANCE AND RELIABILITY UPDATE

RELIABILITY REQUIREMENTS

• Large segment of thepotential market driven byhigh power applications,requiring many chips inparallel

— Solar Inverters— Industrial Drives and Power


— Industrial Drives and PowerSupplies

— EV Drives

• Need to drive to PPM failurerates or better 900V/2.5 mW Half Bridge Module

4x 900V/10 mW MOSFETs per switch position

11MOTIVATION FOR SiC IN EV DRIVES

•Assume Ford Focus EV equipped with 90kW IPM motor

•C-Max 90kW Si IGBT inverter or Wolfspeed 88kW SiCinverter as the traction drive

•Synchronous rectification of SiC devices; no diodes inparallel with SiC MOSFETs


Compared with Si inverter, SiC reduces inverter losses ~67% incombined EPA drive cycle

Simulation data courtesyof Ford Motor Company,based on measuredresults of Wolfspeed900V, C3M 10mOhm SiCMOSFETs

12BENCHMARK 900V SiC & 650V Si (IGBT) POWER MODULES

• 900V SiC XAB350M09HM3 compared with650 V EconoDUAL3 Si IGBT

• 250 V higher blocking voltage

• 10-20x lower body diode recovery, gatecharge, and reverse transfer capacitance.

• Symmetrical 3rd quadrant conduction

• Lower on-state losses


Parameter Wolfspeed XAB350M09HM3 silicon FF450R07ME4_B11Package HT-3000 (custom) EconoDUAL3Blocking voltage (V) 900 650TJ,MAX (°C) 175 150RDS, ON 2.5 / 3.6 N/AIDS @ 150°C (A) 405 430QG (nC) 648 4800QR @ 150°C (µC) 2.02 (0.504 x 4) 35.5Input capacitance, Ciss / Cies (nF) 15.7 (3.93 x 4) 27.5Rev. transfer cap, Crss / Cres (pF) 72 (18pF x 4) 820

13

0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000 1200 1400 1600 1800

Dra

inC

urr

en

t(u

A)

VGS = 0V150°C

ALT-HTRB – 1200V/80 mW GEN 2 MOSFETS

V BD=

1660

V

Tim

e(H

ours

)

C2M0080120D


0 200 400 600 800 1000 1200 1400 1600 1800

Drain Bias (V)

Extrapolated Mean Timeto Failure at 800V

30 Million Hours3400 Years

Accelerated Life Testing under High TemperatureReverse Bias Conditions (ALT-HTRB)• 150°C• Drain Bias Conditions: 1460V, 1540V, 1620V• Test to Failure• Collate Failure Time Statistics

14ALT-HTRB – 900V/65 mW GEN 3 MOSFETS

40

60

80

100

120

140

160

180

200

Leak

age

Cu

rren

t(u

A)

VDS


C3M0065090D MOSFETs – 900V/65mW

• 60 Devices• Parts Run for >1800 hours at 150°C at 1200V+• Three failures from the population as of 1800 hours

VGS = 0V

VDS = 1360V

0

20

0 500 1000 1500 2000

Time (Hours)

15HV LIFETIME PROJECTIONS FOR 900V/65 mW GEN 3 MOSFETS

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

Pro

jec

ted

Lif

eti

me

(Ho

urs

)

T1%(slope based

on Gen 2)


• 900V rating results in 65 years before the first projected 1% of failures

• Avalanche rated: zero fails in 1,000 hours at 50 μA, V > 1200V

1E+01

1E+02

1E+03

500 600 700 800 900 1000 1100 1200 1300

Pro

jec

ted

Lif

eti

me

(Ho

urs

)

Vd Stress (Volts)

First failurein

avalanche

16GATE LIFETIME PROJECTIONS FOR 900V/65 mW GEN 3 MOSFETS

~600M hours~10M hours

MTTF(T50%)


• Extrapolated Intrinsic VGS lifetime of ~600M hours at +15V (DC recommendedoperating point)

• Passed AEC-Q101 qualification of 3 lots x 77 parts with Ø fails in 1,000 hrs atVGS=15V, 150C

T=150°CTested to Failure35 parts per step

17

Part Type Sample Size Total Area Tested Conditions900V/65mW Gen 3 3x77 = 231* 790 mm2 150°C, 15V, 1000 hrs

1200V/25mW Gen 2 3x25 = 75 1380 mm2 150°C, 20V, 1000 hrs

1200V/25mW Gen 2 3x25 = 75 1380 mm2 175°C, 20V, 1000 hrs

1700V/45mW Gen 2 3x25 = 75 1660 mm2 150°C, 20V, 1000 hrs

1700V/45mW Gen 2 3x25 = 75 1660 mm2 175°C, 20V, 1000 hrs

CAS300 Module 6 switches x 665 mm2 125°C (limited by module

HIGH TEMPERATURE GATE BIAS QUALIFICATIONS


CAS300 Module1200V/25mW Gen 2

6 switches x6 die/switch

665 mm 125°C (limited by modulehousing), 20V, 1000 hrs

• 7500 mm2 total die area tested

• Equivalent of 1,200 of C2M0080120D (1200V/80 mW Gen 2)MOSFETs tested for 1000 hours with zero failures

* Full AEC-Q101 Qualification to meet Automotive Qualification Standards

18ACCELERATED HTGB

Part Type SampleSize

Total AreaTested

Conditions Elapsed Time

1200V/25mW Gen 2 290 5350 mm2 175°C, 27V (20V Vuse) 1000 Hours, 0 Fails

900V/10mW Gen 3 240 5540 mm2 175°C, 20V (15V Vuse) 800 Hours (and counting), 0 Fails

5.0E-09

6.0E-09

Gat

eLe

akag

e(A

)

Assuming a voltage accelerationfactor of 4.0 cm/MV:

• A Gen 2 MOSFET that survives


0.0E+00

1.0E-09

2.0E-09

3.0E-09

4.0E-09

0 200 400 600 800 1000 1200

Gat

eLe

akag

e(A

)

Time (Hours)

60 Representative parts1200V/25 mW MOSFETs

• A Gen 2 MOSFET that survivesfor 1000 hours at VGS = 27V isestimated to survive for 50years at VGS = 20V

• A Gen 3 MOSFET that survivesfor 800 hours at VGS = 20V isestimated to survive for 21years at VGS = 15V

SUMMARY

•fraction of total device resistance

— We continue to drive to higher cell density and optimized epitaxy of ourPlanar DMOSFET technology to drive to more efficient MOSFET products

— We are approaching the limits of the planar technology, but there is onemore generation of device that we can achieve

• Any forthcoming technology must match the reliability of the


• Any forthcoming technology must match the reliability of thePlanar DMOSFET platform

• Intrinsic Reliability is superb, but we will continue to examinedefectivity and accelerated test conditions to drive failure ratesdown on large populations of parts

• We have demonstrated T1% Lifetimes of greater than 50 years (GateLifetime and High Drain Bias Lifetime)

next generation sic mosfets performance and …neil/sic_workshop/presentations...2 • the wolfspeed...

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