© 2007

LED manufacturing technologies“The paths to improved luminous efficiency…”

2008 Edition

45 rue Sainte Geneviève, F-69006 Lyon, FranceTel : +33 472 83 01 80 - Fax : +33 472 83 01 83Web: http://www.yole.fr

Nitronex

EPIC 17, rue Hamelin, F-75016 Paris, FranceTel / Fax: +33 1 45 05 72 63 Web: http://www.epic-assoc.com

OSRAMAixtron OSRAMCREELumileds

© 2007 • 2

LED market volume as a function of LED type

Sources: Yole Développement

LED Market

© 2007 • 3 LED Market

Major worldwide players and related position on the value-chain

Region CompanyEpitaxy

LED dies Packaged LEDLED modules

Estimated 2006revenues for LED

businessInGaN InGaAlP

Taiwan

Arima X X

Bright LED X $91M

Epistar X X

Everlight X $258M

Formosa epitaxy X

Genesis Photonics X

Harvatech X $90M

Huga X

KingBright X $231M

LEDTech X $24M

Ligitek X $30M

Lite-On X $294M

Oasis X $55M

Opto Tech X

ParaLight X $26M

Tekcore X

Unity Opto X $82M

VPEC X

Ya Hsin X

© 2007 • 4

Digital Cinema Projectors: introduction• Worldwide total accessible market is about 109,000 cinema

screens in 2007.• A digital cinema playback system including server, media

block and projector can cost up to $200k• Digital Cinema light source can be:

– White light: Texas Instrument 3xDLP technique– 3 lasers (RGB): Sony GLV or Kodak GEMS technique

• In 2006, Texas Instruments had 100% market share in digital cinema projection systems

• Main digital projector makers (based on TI DLP technology): NEC, Christie (market leader in the US), Barco (Market leader in EU and Asia), Digital Projection International

Projection systems market

SONY Grating Light Valve (GLV) technology license from Silicon Light Machine's (bought

by Cypress Semiconductor in 2000).

At EXPO’05, Sony has presented a 10x50 m² screen display with GLV system generating 60,000 lumens

© 2007 • 5 LED technologies

Main manufacturing steps and related options for GaN-based LED

Substrate EpitaxyBuffer layer

EpitaxyActive layers

AlNLow T° GaNAlN/GaN sandwich

SiCSapphireSiliconBulk GaNComposite substrates

InGaN

LED epi-wafer

Front-EndLitho, etching, metallization…

Lateral LED structureVertical LED structureLED dies-on-wafer

Back-Endlevel 0

Back-grindingDicing, Flip-chipLaser Lift-Off: LLODie shaping

LED dies

Back-Endlevel 1

Binning, Pick-and-placePhosphor coatingPackaging, Housing

Packaged LED LED lampSources: Yole Développement

© 2007 • 6

Influence of selected improvements on the four key efficiency parameters

Internal Quantum Efficiency

Electrical efficiency

Extraction efficiency

Packaging efficiency

Use high-quality growth substrate to improve active layers crystalline quality ++ + 0 0

Improve quantum well structure ++ 0 0 0

Improve Ohmic contacts 0 ++ + transparent- Opaque 0

Remove substrate (LLO) and flip-chip 0 + ++ 0

Surface texturing and photonic crystals 0 0 ++ 0

Increase die size 0 + - -

Increase current - 0 0 0

Decrease active layer thickness 0 0 + 0

Improve phosphor material efficiency 0 0 0 ++

Improve lenses and optics 0 0 0 ++

LED technologies

© 2007 • 7

Various techniques to improve white LED efficiency

Techniques to improve LED efficiency

New growth substrates

Photonic Crystals

Material Front-End PackagingBack-End

Laser Lift-OffTemporary bonding

Flip-Chip with reflecting

back contacts

Transparent top contacts

Binning

Phosphors

Dicing / Scribing

Surface texturing

LED technologies

© 2007 • 8

• Molecular Imprints (US) is developing a low-cost imprinting technique that increases the extraction efficiency of LED chips:

– Nano patterning of photonic crystals is done thanks to a combination of both DRIE + Nanoimprint processes:

• Imprinted depth of the structure are ~ 250nm deep• Resolution: from 50 nm to 300 nm

– Whole-wafer template technology one single step to imprint the entire LED wafer. To achieve this, they imprint intermediate quartz replicas that can each one imprint ~ 1 000 wafers. Thanks to this approach, one template manufactured by e-beam lithography can imprint ~ 1 000 000 of wafers…

– Process cost is < 20$/wafer– Throughput is ~ 20 wafers/hour– Wafer sizes: 2”, 3” to 4”– Time to market at production level: by 2008

Nano-imprint lithography, a key technology for photonic crystal LEDs

GaN epiwafer prepared for etching to form a photonic crystal LED

GaN

Imprint resist

SiO2

Photonic crystals & texturing

© 2007 • 9

Thin-wafer handling: different solutions

Thin-wafer handling with

Temporary bonding No intermediate layer

Mobile electrostatic carrier (IZM)Handling capabilities can also be integrated to thin wafer grinding equipment suppliers (DISCO,

Accretech…)

To a rigid support carrier With no support carrier

Equipment using wax

(TEL)

Equipment using adhesive tapes: thermal, solvent or UV release (EVG, SUSS…)

Handling thin wafers by use of vacuum forces or rigid borders (Allvia,

Semitool)

Temporary bonding

© 2007 • 10

What is Binning?

Finished LED

Wavelength bins, 2.5-20 nm wide

Vf bins, 200 - 500 µV wide

Flux bins: 30% + ranges

100% test• Functional• Flux, Color, Vf• Each LED Labeled by bin

Vf

Flux

Color

Full Distribution

Binning

© 2007 • 11

Main agreements and cross-licenses in LED business

License to

Cross-license

Supply to

Patents and licenses

© 2007 • 12

UV emission wavelength depends on the Al content in the AlGaN alloy

• The concentration of Al will have a direct effect on the wavelength of the AlGaN device:

• 100% Al: pure AlN: 210 nm• AlGaN with 45% Al: 280 nm• AlGaN with 15% Al: 360 nm

UV-LED and AlN

0%

20%

40%

60%

80%

100%

200 250 300 350 400 450

λ (nm)

% o

f Al o

ver G

a in

AlG

aN a

ctiv

e la

yer

AlN bulk substrateswill be needed

Hetero-epitaxy onforeign substrate is

possible

Al has a strong affinity to the oxygen. For Al contents above

30%, oxygen contamination becomes an issue

© 2007 • 13

Introduction: green is missing…

• Efficient green emitters (LED or Laser diodes) at 555 nm are required for several solid-state lighting applications, including Digital Light Processing (DLP) projectors, large scale projection systems, color displays, and controllable red/green/blue (RGB) white light.

• A “green gap,” however, falls between the two LED device material systems-aluminum gallium indium phosphide (AlGaInP) and gallium indium nitride (GaInN)-that are used to produce visible-spectrum solid-state light sources.

The “green gap”

The power-conversion efficiency curves of two important material systems used for solid-state

light are separated by a “green gap” that will need to be filled to achieve performance goals for

general illumination