Monolith Semiconductor Inc.neil/SiC_Workshop... · Gate BTS: Short-term Bias Temperature Stress up...

Monolith Semiconductor Inc.

Bringing SiC to our World.

ARL SiC MOSFET Workshop14 August 2015

Kevin Matocha, President

408 Fannin AveRound Rock, TX 78664

2

Acknowledgments

Monolith Semiconductor: Bringing SiC to our World.

We acknowledge our sponsors who have supported Monolith Semi’s development of SiC diodes and MOSFETs:

• DE-AR0000442• W911NF-14-2-0112

• DE-SC0011395• IIP-1332039• ECCS-0335765

Office of Science SBIR Prog. Office

150 mm

3Monolith Semiconductor Inc.

Monolith Semi: A fabless manufacturer of SiC diodes and MOSFETs

SiC epiwafervendors

150mm Silicon

Foundry

Assembly vendors


• MOSFET with best performance and reliability• Low cost manufacturing in high-volume CMOS fab• Low capital, Fast time to market

75 mm

150 mm

4Monolith Semiconductor Trajectory

December 2012 Monolith Semiconductor incorporated

May 2013

Demonstrated SiC DMOSFETs 1700V, 5.5 mΩ-cm2

5 AmpStable at 225°C

December 2013

Inked agreement with domestichigh-volume 150mm silicon foundry

2014

Demonstrated first SiCDMOSFETs on 150mm wafers in USA

2013 2014

2015

Engineering samples to select customers

2015

2014

Demonstrated 1200V SiCSchottky diodes on 150mm wafers

5Monolith Semiconductor: Bringing SiC to our World

2014: Monolith Semi relocated to Round Rock (Austin), TX

Ithaca, NY

Round Rock, TX

6

Monolith Semi’s SiC Power MOSFET Technology

Monolith Semi’s SiC MOSFET Technology

Steady state performanceOn-resistance, blocking voltage

Transient behaviorSwitching losses under high-speed switching, fast dV/dt > 50V/ns

Gate oxide stability and reliabilityExploring the temperature boundaries

Remaining items to resolve

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

Dra

in C

urre

nt (A

)

Drain Voltage (V)

Vgs=0V to 20V, 5V steps

0

0.5

1

1.5

2

2.5

0 200 400 600 800 1000 1200 1400 1600 1800

Dra

in C

urre

nt (m

A)

Drain Voltage (V)

Measured with VGS=0 V

7

Packaged device resultsOn-resistance: 45 mΩ (VGS=20V)

50 mΩ (VGS=15V)

Specific on-resistance: 3.1 mΩ-cm2

Blocking Voltage: 1700V

Monolith Semi’s 1200V, 45 mΩ (3.1 mΩ-cm2) DMOSFETs on 150mm SiC wafers.

RDS,on=45 mΩRsp,on=3.1 mΩ-cm2

0

2

4

6

8

10

12

14

16

0 25 50 75 100 125 150 175 200

Spec

ific

on-r

esis

tanc

e:

R sp,

on (m

Ω-c

m2 )

Temperature (°C)

8

Specific on-resistance vs. Temperature

Monolith Semi’s SiC MOSFETs are suitable for 175°C operation.

Monolith Semi’s SiC MOSFETs have superior on-resistance at all temperatures.

Gen1

Gen2

Supplier 1

Supplier 2

9

Switching losses of Monolith Semi’s 1200V, 45 mΩ SiC MOSFETs

Monolith Semi’s SiC MOSFETs have switching loss 10x lower than Si IGBTs.

Device:Monolith Semi 1200V, 45 mΩSiC DMOSFETs in TO-247

Test conditionsVDS=700 VID=20 A and 30 A

Characterized switching energy with varying gate resistance from RG=1 to 10 Ω.

VGS

VDS

ID

IL

30A

700V

RG=5.1 Ω

20A

2.96 2.97 2.98 2.99 3 3.01 3.02 3.03 3.04-5

0

5

10

15

20

25

30

35

Time (µs)

Curr

ent (

A)

10 Ω5.1 Ω2 Ω1 Ω

10

Switching loss characterization of Monolith Semi’s 45 mΩ SiC MOSFETs

Monolith Semi’s SiC MOSFETs have switching loss 10x lower than Si IGBTs.

ID

20ns

2.96 2.97 2.98 2.99 3 3.01 3.02 3.03 3.04-100

0

100

200

300

400

500

600

700

800

Time (µs)

Volta

ge (V

)

10 Ω5.1 Ω2 Ω1 Ω

Rg(ext) (Ω) Eon (mJ) ID=19.5A

Eoff (mJ) ID=19.5A

Eoff (mJ) ID=28.5A

10 0.61 0.23 0.39

5.1 0.50 0.16 0.27

2 0.42 0.11 0.2

1 0.40 0.11 0.17

20ns

Turn-off at 30A, 700V occurs in less than 20 ns

Turn-on and turn-off times are dominated by packaging parasitic inductances @ RG ≤ 2 Ω.

11

SiC MOSFET Gate oxide reliability

Monolith Semi’s SiC MOSFET Technology

The gate oxide is considered the Achilles heel of Silicon Carbide MOSFETs, particularly for high temperature operation

We have spent must of 2014/2015 to:- Improve the wearout reliability of SiC gate oxides- Reduce the extrinsic failure rates- Improve threshold voltage stability- Evaluate devices at temperatures up to 275°C

12

Monolith Semi: SiC MOSFET Gate Oxide Reliability @ 300°C – testing @ NIST

Monolith Semi’s SiC gate oxides project sufficient life at high temperatures.

Gate oxide reliability

NIST logo

1e+1

1e+2

1e+3

1e+4

1e+5

1e+6

1e+7

1e+8

1e+9

1e+10

Failu

re ti

me

(sec

onds

)

25 30 35 40 45 50Voltage

0.003

0.014

0.045

0.2

0.6

Prob

abilit

y

1e+1 1e+2 1e+3 1e+4 1e+5 1e+6Failure time (seconds)

38V41V 43V45V47.5V

T=300°C

No early failures, even at 300°C.

At T=300°C and VG=20V, extrapolated 1% failure life is > 1010 sec (100 yrs).

We continue to validate the reliability of Monolith gate oxides.

1%

50%

SiC gate oxide reliability characterization by NIST.

Constant voltage TDDB stress testing of 50 nm SiC gate oxide.

T=300°C

13

Monolith Semi SiC MOSFETs: ARL Testing – NBTI at 175°C

Monolith Semi’s threshold voltage shifts less than 175mV after 200 hrs @ 175°C.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1E+2 1E+3 1E+4 1E+5 1E+6 1E+7V T(V)

Cumulative Stress Time (s)

NBTS -15V 175°C Dev G4 2014

Measured at 28 °C

Measured at 175 °C

Dr. Ron Green and Dan Habersat @ Army Research Lab tested Monolith Semi’s 1200V, 45 mΩ MOSFETs packaged in TO-247

Tested at VGS=-15V @ 175°C for extended stress times and characterized the threshold voltage shift.

Less than < 175mV shift after 200 hrs at 175°C.

14

Monolith Semi power MOSFET NBTI/PBTI: Testing the limits, 175°C and beyond

Monolith Semiconductor: Bringing SiC to our WorldMonolith Semiconductor Proprietary

Bare die mounted to a copper plate with Silver paint, die are in room air.

Used “ARL” Test method for NBTI/PBTI hysteresis measured at temperature

Set temperature, stabilize.

Bias VGS=-15V, 60 secSweep -15V to +20V, VDS=0.1VBias VGS=+20V, 60 secSweep +20V to -15V, VDS=0.1V


Threshold voltage is defined at constant current of 1mA.

15

Monolith Semi SiC MOSFETs: High temperature transfer characteristics


Comparison of transfer characteristics measured after VGS=-15V, 60sec.

1.E$10&

1.E$09&

1.E$08&

1.E$07&

1.E$06&

1.E$05&

1.E$04&

1.E$03&

1.E$02&

1.E$01&

1.E+00&

$1& 0& 1& 2& 3& 4& 5&

Drain&Cu

rren

t&@Vd

s=0.1V

&(Amps)&

Gate&Voltage&(V)&

Transfer&Characteris@cs&25°C&to&275°C&

25C&

150C&

175C&

225C&

250C&

275C&

16

Gate BTS: Short-term Bias Temperature Stress up to 275°C, 60 and 1000 seconds


Mounted die to copper plate using Silver paint.

Test method:

Set temperature, stabilize



1.E$09'

1.E$08'

1.E$07'

1.E$06'

1.E$05'

1.E$04'

1.E$03'

1.E$02'

1.E$01'

1.E+00'

$1' 0' 1' 2' 3' 4' 5'

Drain&Cu

rren

t&@Vd

s=0.1V

&(Amps)&

Gate&Voltage&(V)&

CY1452@05&@&175°C&@&60&and&1000sec&

$15V'to'20V,'60s'

+20V'to'$15V,'60s'

$15V'to'20V,'1000s'

+20V'to'$15V,'1000s'

1.E$09'

1.E$08'

1.E$07'

1.E$06'

1.E$05'

1.E$04'

1.E$03'

1.E$02'

1.E$01'

1.E+00'

$1' 0' 1' 2' 3' 4' 5'

Drain&Cu

rren

t&@Vd

s=0.1V

&(Amps)&

Gate&Voltage&(V)&

CY1452@05&@&275°C&@&60&and&1000sec&

$15V'to'20V,'60s'

+20V'to'$15V,'60s'

$15V'to'20V,'1000s'

+20V'to'$15V,'1000s'

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

100 150 200 250 300

Threshold)Volta

ge)(V

)

Temperature) (°C)

17

Gate BTS: Short-term Bias Temperature Stress up to 275°C


Observe <300mV hysteresis even up to 275°C.

NBTI/PBTI data suggests we can extend SiC MOSFETs to beyond 175°C.

Threshold Voltage after stress Hysteresis ΔVT: between -15/+20V

+20V

-15V

Solid: 60 sec stressDashed: 1000 sec stress 0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

100 150 200 250 300De

lta_V

T,*VT

2,VT

1*(Volts)

Temperature* (°C)

60 sec

1000 sec

18

SiC MOSFET NBTI/PBTI: Short-term Bias Temperature Stress up to 275°C


Performed NBTI/PBTI on bare die for short times up to 275°C.

Observe <300mV hysteresis even up to 275°C.

NBTI/PBTI data suggests we can extend Monolith SiC MOSFET beyond 175°C.

How do we assemble devices to take advantage of Monolith Semi’s high-temperature capability?

Before Stress

After 275ºCStress

!0.15

!0.1

!0.05

0

0.05

0.1

0 200 400 600 800

Threshold)Vo

ltage)Shift,)ΔVT

)(Volts)

Time)(hours)

High8Temperature)Gate)Bias:)810V,)T=175°C

19

Monolith Semi Qualification Testing: HTGB +20/-10V, 750 hrs @ 175°C

Monolith Semi SiC MOSFETs have state-of-art threshold voltage stability @ 175°C.Monolith Semiconductor Proprietary

For Monolith Semi devices, VT shift saturates in < 48 hours.

Monolith Semi SiC MOSFET HTGB results after 750 hrs @ 175°C:HTGB @ -10V, 175°C: < -100mV shift after 750 hrs.HTGB @ +20V, 175°C: < +250mV shift after 750 hrs.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 200 400 600 800

Threshold)Vo

ltage)Shift,)ΔVT

)(Volts)

Time)(hours)

High8Temperature)Gate)Bias:)+20V,)T=175°C

Solid lines:

Dashed: commercial SiC MOSFETs

Solid lines:

Dashed: commercial SiC MOSFETs

Monolith

Monolith

20

Monolith Semi’s SiC Power MOSFET Technology

Monolith Semi’s SiC MOSFETs demonstrate world-leading performance.

Developed SiC MOSFET production on high-volume 150mm silicon line

Steady state performanceDemonstrated 1200V SiC MOSFETs, 3.1 mOhm-cm2

Superior performance up to 175°C

Transient behaviorDemonstrated switching with 10% of the losses of IGBTs

Gate oxide stability and reliabilityDemonstrated short-term stability even up to 250°CDeveloped high-quality SiC gate oxidation processCharacterized “silicon-like” intrinsic gate oxide reliabilityVerified gate oxide reliability up to 300°CDemonstrated state-of-art threshold stability at 175°C+, 750 hours

21

Remaining items to resolve

Qualification tests to ensure field reliability – SiC specific

Gate oxide reliability predictions and operating life:Are we really as reliable as silicon devices?How do we validate this? What are the error bars?How can we prevent and screen extrinsic defects?

Assembly: What assembly techniques are required to achieve > 200°C

Main objective: Develop silicon-like levels of confidence in SiC products.

Monolith Semiconductor: Bringing SiC to our World


Monolith Semi has developed world-class SiC MOSFETs in a scalable, high-quality manufacturing environment.

Our company focus is to deliver qualified SiC MOSFETs to our customers.

Bringing SiC to our World.

Monolith Semiconductor Inc.neil/SiC_Workshop... · Gate BTS: Short-term Bias Temperature Stress up...

Documents

Transcript of Monolith Semiconductor Inc.neil/SiC_Workshop... · Gate BTS: Short-term Bias Temperature Stress up...