GaN/Si Power Devices Addressing Energy Conversion ...yess2012.france-science.org/2012/04/yess2012_metras_032112.pdfGaN on Si © CEA 2011. All ... Opportunities for GaN technology SiC/GaN

© CEA 2011. All rights reserved Any reproduction in whole or in part on any medium or use of the information contained herein

is prohibited without the prior written consent of CEA © CEA. All rights reserved

YESS – GaN/Si opportunities and challenges - 03/20/2012 1 CONFIDENTIAL

GaN/Si Power Devices

Addressing Energy Conversion Applications :

Requirements for nanoscale engineering

[email protected]



YESS – GaN/Si opportunities and challenges - 03/20/2012 2

Outline

Context

Sustainability Policy and Power Electronics

Power Electronics Requirements

Wide BandGap Technologies

GaN and SiC vs Silicon

GaN technology: a real opportunity?

GaN range of application

Challenges to be addressed




Outline

Context

Sustainability Policy and Power Electronics










Sustainability Policy and Power electronics

Power Electronics is one of the key solutions for sustainable energy

Renewable energy

Better energy efficiency

Increased awareness concerning

environmental issues and sustainable

energy:

. Transport: -20% Greenhouse gas

emissions by 2020

. Energy: -23% Energy usage by 2020





Improvement in conversion efficiency

Reduced losses (switching and conduction)

Higher Voltage

Higher Current

Higher Frequency

Lighter cooling systems

Higher temperature

Reduced volume and weight

Higher integration

Smaller passive components (higher frequency)

Some of the Silicon limits have been reached!

…an opportunity for wide bandgap technology




Outline

Context











Wide BandGap Technology: GaN and SiC

0.1

1

10

100

1000

Lo

gari

thm

ic S

cale

Johnson Keyes Baliga Baliga RF

Si

GaAs

GaN

4H-SiC

Bandgap energy Eg

Higher temperature: x3

Breakdown electric field

Reduced losses : x100

(unipolar device)

Higher voltage: x10

Electron mobility and

saturated velocity

Higher frequency: x10

Figures of Merit

Physical properties

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Eg (eV) Ec (MV/cm) nsat

(107cm/s)

k

(Wcm-1K-1)

Si

GaAs

GaN

4H-SiC

(BV and RF) (°C) (Pw) (Pw and RF)




Positioning of GaN vs SiC & Si

Characteristics & Maturity of widebandgab materials

Limits of SiC / Si SiC Schottky Diodes commercial availability

Cost is the main issue

Substrate size

Opportunities for GaN Possibilities for substrates > 6 inches

Technology takes advantage of growth

in lighting and RF applications

Process with relaxed Temperature budget




Positioning of GaN vs SiC & Si

GaN on Si




Opportunities for GaN technology

SiC/GaN

Hybrid LED 7.4 B$

Laser diode & LED 9.5 B$

Power Electronic 264 M$

RF Power 230 M$

SiC/GaN devices Market (2007) Source: Yole Development

Leverage of R&D and production efforts on GaN for

lighting applications

Cost effective technology

Epitaxy on (111) silicon substrate

Low Si substrate cost

Large wafer potential

Process compatibility with Si




100W

1KW

10 KW

100 KW

2010 2012 2014 2016

Applications Roadmap for GaN power devices

Electric

Drive 600V, 10-20A

PV

Converters

Automotive

Hybrid/EV

600V , 30/50A

600V , 200 A

1200V, 100A Si IGBT SiC

Si MOSFET

Si IGBT

Si MOSFET Computing

Network

Com°

15V, 20-30A Servers &

Storage

http://www.renault.com/fr/Innovation/vehicule-electrique/Pages/ZOE-ZE-Concept.aspx




Value of GaN in various applications

DC/DC Convertors

Source : IR

Source : IR

Electric Drive

PV Panel Control

(Robustness,

Security)




Outline

Context











State of the art in GaN transistor is based on RF HEMT

GaN on semi-insulating SiC

Key requirements need to be fulfill « low cost » and « high

voltage - high power - high frequency »

Low cost (silicon substrates) and ...

High breakdown voltage

Low Ron & high current operation

Vertical operation

Thick and high quality GaN epilayers on Silicon

High quality passivation and edge termination

MIS gate

Low Ron heterojunction, optimized bottom contact

Normally-off operation

Specific epilayers to control the conduction

High T° operation – thermal management

Devices transfer on metal (Copper)

Key requirements for GaN power transistors

Substrat résistif

GaN

GaN-AlGaN SiN, SiO2, …

Source Grille Drain

GaN-AlGaN Si3N4, SiO2, …

Source Grille Source

Drain




Epitaxial layers : GaN on <111> Si substrates

SIMS analysis

Angular XPS in AlGaN

AFM surface analysis

EDX TEM Al in AlGaN

III-V Lab TEM structure

► Advanced characterization (TEM, TEM-EDX, AFM, SIMS, DRX, XPS,...)

• µ = 1650 cm2/V/s - R□ = 350 - 400 W

Plane view TEM

ToPoGaN1




► Dielectric for passivation and MIS gate

MIS and passivation layers

2nm

2nm

2nm

2nm

2nm

2nm

2nm

2nm

2nm

2nm

AlGaN

Al2O3

HfO2

Al2O3

HfO2

Al2O3

HfO2

Al2O3

HfO2

Al2O3

HfO2

Grille

GaN

30nm

Si substrate

GaN active layer

Source Drain

Gate

AlN/GaN buffer

ToPoGaN1

1,0E-09

1,0E-08

1,0E-07

1,0E-06

1,0E-05

1,0E-04

1,0E-03

1,0E-02

1,0E-01

1,0E+00

-12 -10 -8 -6 -4 -2 0 2 4

ID (A

/mm

)

VG (V)

Schottky (Ni/Pt/Ti)

High-K MIS • Strong know-how in sub 32nm HighK

metal gate, reused for GaN devices

• ALD HfO2/Al2O3 multi-stack dielectric

• Mixed with SiN passivation

n xHfO2/Al2O3




• Improved epilayers for High Power devices

• Schottky gate HEMT : Ron = 12 mW.cm2

• Large transistors with MIS gate on-going

700V Normally-on HEMT

1,E-07

1,E-06

1,E-05

1,E-04

1,E-03

1,E-02

1,E-01

1,E+00

0 200 400 600 800 1 000 1 200

I (A

/mm

)

V (V)

Vr > 700V

III-V Lab 3 µm epilayer on 6" Si

0

2

4

6

8

10

12

0 3 5 8 10 13

ID (A

)

VD (V)

Vg=+1V, 0V, -1V

Vg=-2V

Vg=-3V

Vg=-4V

Lg=2µm

► Electrical lots for device demonstrators

ToPoGaN1




Packaging

► Packaging technology for High Temperature operating conditions

Qualification of low T sinterable Ag

High T polymer (LCP) and Metal Matrix Composites

From DBC to moulded multi-layer substrate using Powder Injection Moulding (PIM)

Chip on metal by direct bonding, for improved Rth

3D package Metal direct bonding




Conclusions

GaN on Silicon Devices offers a wide range of

opportunities for new research topics

Engineering at the nanoscale is of the

essence

Many opportunities for cooperation between

French and US engineers and scientists




Thanks for your attention

Documents

GaN/Si Power Devices Addressing Energy Conversion ...yess2012.france-science.org/2012/04/yess2012_metras_032112.pdfGaN on Si © CEA 2011. All ... Opportunities for GaN technology SiC/GaN