is it the end of the road for silicon in power conversion ...€¦ · ieee-bctm 2011 is it the end...

IEEE-BCTM 2011

Is it the End of the Road for

Silicon in Power Conversion?

Paper 7.1

Is This the End of The Road for

Silicon in Power Conversion? Alex Lidow PhD

Efficient Power Conversion Corporation

909 N. Sepulveda Blvd.

El Segundo, California 90245

2

• Why Gallium Nitride?

• Breaking down the barriers

• What the future might hold

• Conclusion

Agenda

Smaller Die Sizes

Why Gallium Nitride?

0

1000

2000

3000

EPC1010 Si7462DP FDMS2672 IRF6641

FOM = Rdson x Qg (200V)

Better Figure of Merit

Why Gallium Nitride?

6

Dielectric

GaN

- - - - - - - - - - - - - - -

Si

AlGaN Electron Generating Layer

Aluminum Nitride

Isolation Layer

D G S - - - -

eGaN FET Structure

Two Dimensional

Electron Gas (2DEG)

GaN

Silicon

G G Source

Drain

Metal 2

Metal 3

Via 2 Metal 1

Passivation

7

eGaN FET Structure

8

Flip Chip Assembly

HEATSINK

Breaking Down the Barriers

• Does it enable significant new capabilities?

• Is it easy to use?

• Is it VERY cost effective to the user?

• Is it reliable?

Breaking Down the Barriers

• Does it enable significant new capabilities?

• Is it easy to use?

• Is it VERY cost effective to the user?

• Is it reliable?

11

Buck Converter

Advantage:

• High power density

and high efficiency

Efficiency vs Frequency @

1.2Vout / 5A

12

62%

64%

66%

68%

70%

72%

74%

76%

78%

80%

82%

84%

86%

88%

90%

92%

300 400 500 600 700 800

Effi

cie

ncy

(%)

Switching Frequency (kHz)

MOSFET @ 12Vin

MOSFET @ 24Vin

MOSFET @ 48Vin

eGaN FET @ 12Vin

eGaN FET @ 24Vin

eGaN FET @ 48Vin

13

12VIN – 1.2 VOUT Buck Converter

Efficiency at 1 MHz

14

Isolated Full Bridge Converter

Advantage:

• Isolation and high power

density at high power 36~75 V

12 V

15 A

180 W

15

Efficiency comparison @ 12 VOUT

eGaN FET @ 333 kHz vs MOSFET @ 250 kHz

Isolated Full Bridge Converter

0

10

20

30

40

50 500

Gai

n (d

B)

Frequency [MHz]

EPC1012 Maximum Gain Vs Frequency

High Frequency Capabilities

1000

16

17

High Frequency Capabilities

Breaking Down the Barriers

• Does it enable significant new capabilities?

• Is it easy to use?

• Is it VERY cost effective to the user?

• Is it reliable?

It’s just like a MOSFET

Is it easy to use?

except for TWO things

(1)

The high frequency capability makes circuits

using eGaN FETs sensitive to layout

(2)

eGaN FETs have a lower maximum gate voltage

than power MOSFETs

20

Integrated Gate Driver Solution

LM5113 from National Semiconductor

Breaking Down the Barriers

• Does it enable significant new capabilities?

• Is it easy to use?

• Is it VERY cost effective to the user?

• Is it reliable?

Silicon Vs eGaN Wafer Costs

Starting Material

Epi Growth

Wafer Fab

Test

Assembly

OVERALL

2010 2015

same same

higher

same

same

lower

lower

same

lower

~same?

lower! higher

22

Breaking Down the Barriers

• Does it enable significant new capabilities?

• Is it easy to use?

• Is it VERY cost effective to the user?

• Is it reliable?

Reliability Key Issues

• Current Collapse

• Temperature Cycling and Humidity Sensitivity

• Operating Life

Reliability Key Issues

• Current Collapse

• Temperature Cycling and Humidity Sensitivity

• Operating Life

No Current Collapse

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 500 1000 1500 2000 2500 3000

No

rmal

ize

d R

DS(

ON

)

Stress Hours

HTRB 150C EPC1010 RDS(ON)

Reliability Key Issues

• Current Collapse

• Temperature Cycling and Humidity Sensitivity

• Operating Life

TC and H3TRB

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

0.0040

0 200 400 600 800 1000

RD

S(O

N) (o

hm

)

Stress Hours

EPC2015 RDS(ON) after 40V at 85oC/85%RH

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 200 400 600 800 1000

No

rmal

ize

d R

DS(

ON

)

Stress Cycles

EPC2001 RDS(ON) after TC -40 to 125oC

Reliability Key Issues

• Current Collapse

• Temperature Cycling and Humidity Sensitivity

• Operating Life

Operating Life

0.9

0.95

1

1.05

1.1

0 500 1000 1500 2000No

rmal

ize

d E

ffic

ien

cy

Stress Hours

EPC9002 Efficiency after Op Life Test at 85oC

47

25

100

250400

1.00

10.00

100.00

1000.00

0 200 400 600 800 1000 1200 1400

Rat

ed

RD

S(O

N)m

W

Rated VDSS(MAX)

2009

2011

2012

EPC’s eGaN FET products will extend to 600V in 2011 and to

900V and 1200V in 2012 if there is adequate customer interest

Beyond 600 Volts

100 mW

5x6mm

PQFN

400 mW

5x6mm

PQFN

250 mW

5x6mm

PQFN

150 mW

8x8mm

PQFN

90 mW

8x8mm

PQFN

LGA

Package

24

Driver On Board

Beyond Discrete Devices

Full-Bridge with Driver and Level Shift

Discrete FET with Driver

25 32

Is it the end of the road for

Silicon?

• Many new applications are enabled due to

quantum leap in frequency capability

• Devices are easy to use because they are

similar to a power MOSFETs and

commercial IC drivers are available

• The technology will soon be lower cost-

per-function than silicon.

• Reliability testing shows that parts are

capable in commercial applications.

The end of the road

for silicon…..

is the beginning of

the eGaN FET

journey!

34