MOCVD Technology for LEDopticsjournal.net/upload/post/201106/PT110606000047KgNj.pdf08.10.2010 P 5 Compound Semiconductor Systems Leading edge design to manufacturing Flexible wafer

Prof. Dr.-Ing. Michael HeukenVice President Corporate Research and Development

AIXTRON AG,

Fon: +49 (241) 8909-154, Fax: +49 (241) 8909-149,

Email: [email protected]

RWTH Aachen, University of Technology , Templergraben 55,D-52074 Aachen, Germany

MOCVD Technology for LED

08.10.2010P 2

Outline

� Introduction

� Basic MOCVD Technology

� Advantages of Showerhead MOCVD Reactor

� The Planetary Reactor

� LED Processing

� Conclusion

08.10.2010P 3

AIXTRON AG, Aachen

Audi R8 LED Headlight ▪ Nimbus LED Ceiling Light 12 W ▪ LED Street Lighting

Samsung LED-TV 9000 Series ▪ LED Monitor Dell G2410 ▪ LED Toshiba Portégé R500

Example of Products with LEDs

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MOCVD = MetalorganicChemical VaporDeposition

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Compound Semiconductor Systems

� Leading edge design to manufacturing

� Flexible wafer configuration from 2”-300 mm

� Configurable common platform

� Integrated automated solutions

� Customized turn-key solutions

� Proven industry standard & market leader

Planetary Reactor ®

AIX 2800G4, 42x2”

Close Coupled Showerhead ®

CRIUS®, 31x2“

Integrated Concept (IC) System

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MOCVD Source Comparison

Group V Ammonia bottle, capacity: 26,5 kg

Group IIITMGa

Bubbler, 100 g

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gas mixing unitTransport of gases within tubesSwitch by valveControl via MFC, pressurecontroller

For metalorganic sources

Bubbler containing MO source(e.g. TMGa, TMIn, TMAl)

Each bubbler is placed in a thermally controlled bath (Lauda bath)

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Integrated Concept Design

Gas Blending Cabinet

Pump and Run-Vent Cabinet

Reactor Cabinet

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Basic MOCVD Process in Reactor

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Sapphire Substrates: R&D to Production

2"3"

4"

6"

8"

12"

UHB LEDsElectronics

UHB LEDsElectronics

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Cross section of an epitaxial wafer

Cross section of a human hair

Diameter: 100 micronEpitaxial layersgroup III and V elementsthickness: 0.02 micron to 4 micron

Substrate wafernormally madefrom Gallium Arsenide (GaAs) or Indium Phosphide (InP)

350-650micron

2-6 inches(1 micron = 1/1000 mm)

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A cross section of a light emitting diode (LED)

Substrat-Wafer(ca. 5 cm diameter)

+

-

0,00001mm thin layers likeGaN, GaInN

Light

This wafer will beseparated to ca. 10.000 singleLED-Chips

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Advantage of going large

Maximum reactor utilisation

42x2“Area: 100% ref.Yield: 100% ref.

11x4“Area: 101%Yield: 110%*

6x6“Area: 125%Yield:140%*

* 2 mm edge exclusion

Same MOCVD reactor allows up to 40% increase in productivity

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� High Efficiency CoO

� Vertical Flow Designw/o Discontinuity in the Center Yield

� Robust Design Uptime

Showerhead Principle (19x2'')

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Close Coupled Showerhead: The Concept

CCS ���� intrinsic uniform

Carrier and MO into upper showerhead

Carrier and Hydrides into lower showerhead

Ga DistributionMMGa Distribution

radius

Growth-rate

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Thickness uniformity of an LED structure on 200 mm diameter sapphire

� Thickness mappings showing thickness uniformity of σ = 2.6% (with 4 mm edge exclusion).

� Thickness uniformity dominated by high temperature GaN layers.

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Pla

neta

ry R

eact

or®

Pla

neta

ry R

eact

or®

42x2” Nitride Reactor After Fully Loaded Run

Total wafer area 42x2“ = 851cm2

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56x2 inch / 14x4 inch / 8x6 inch / 5x8 inch56x2 inch / 14x4 inch / 8x6 inch / 5x8 inch

Capacity Increase: + 33%*

*compared to AIX2800G4 HT

AIXTRON G5HT: Larger ChamberG5 HT

� Throughput ↑� Large wafers (4”, 6”, 8”)� No particles� Continuous production� Higher yield� Automation� Reduced footprint� Cost of ownership ↓

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Sapphire ~430 µm(0.3deg off-cut from 0001)

4 µm Undoped GaN

2 µm GaN:Si(5x1018)

3x u-InGaN QWs (2.5nm) + GaN:Si(5x1017) QBs (12nm)

2x u-InGaN QWs (2.5nm) + u-GaN QBs (12nm)

40nm AlGaN:Mg

QWs @ ~740°, QBs @ ~860°C

~25nm GaN Nucleation layer

10nm GaN:Mg

900mBar2µm/hr

400mBar4µm/hr

400mBar

266mBar 100 nm GaN:Mg

GrowthPressure

Generic LED Structure

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e electron D donor levelh defect electron / hole A acceptor leveleh exciton / electron-hole pair

Energy ofconduction band

Energy ofvalence band

Conduction band

Valence band

energy gap / band gap

Photon

D D

A A

Recombination between conduction and valance band

E

X

e

h

hh

ee

e

h

eh

1a 1b2a

2b2c

r

2d2e

e

eh

h

Photoluminescence

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EL Test Structure on 6 inch Sapphire

With p-GaN cap added and In contacts

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III-N Based LED Processing

LED on sapphiresubstrate

LED on SiCsubstrate

Epi-Wafer

MESA Litho

1

RIE MESA etch2

p-layern-layer

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3 n-ContactLitho

14n-ContactEvaporation + lift-off

25p-ContactLitho

LED on sapphire substrate LED on SiC substrate

III-N Based LED Processing

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Al 2O3

n-GaN

p-GaN

anode

cathode

transparent contact active zone

p-Contactevaporation+ lift-off

36

LED on sapphire substrate LED on SiC substrate

III-N Based LED Processing

scribing+ dicing 4

7

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Inside the LED…

…the chip

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Design of white LED

Compound Semiconductor, July,2003, (Nichia)

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Conclusion

� Basic MOCVD Technology explained

� Advantages of Showerhead MOCVD Reactor

� Advantages of Planetary Reactor

� Simple LED Processing

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www.aixtron.com

For further information, please contact:

Prof. Dr. Michael HeukenAIXTRON AG, Kaiserstr. 98, D-52134 Herzogenrath

Germany

[email protected]