© 2017

From Technologies to Market

MicroLEDDisplays 2018

From Technologies to Market

Courtesy of Sony

Sample© 2018

2

OBJECTIVE OF THE REPORT

Deep understanding

of the technology,

current status and prospects,

roadblocks and key players.

• Understand the Current Status of the µLED Display Technologies:

• What are microLED? What are the key benefits? How do they differ from other display technologies? What are the costdrivers?

• What are the remaining roadblocks? How challenging are they?

• Detailed analysis of key technological nodes: epitaxy, die structure and manufacturing, front plane structure and display designs,color conversion, backplanes, massively parallel pick and place and continuous assembly processes, hybridization, defectmanagement, light extraction and beam shaping.

• Which applications could µLED display address and when?

• Detailed analysis of major display applications: TV, smartphones, wearables, augmented and virtual reality (AR/VR/MR), laptopsand tablets, monitors, large LED video displays...

• What are the cost targets for major applications? How do they impact technology, design and process choices?

• How disruptive for incumbent technologies: LCD, OLED, LCOS…

• MicroLED display application roadmap, forecast and SWOT analysis

• Competitive Landscape and Supply chain

• Identify key players in technology development and manufacturing.Who owns the IP?

• Potential impact on the LED supply chain: epimakers, MOCVD reactor and substrate suppliers.

• Potential impact on the display chain: LCD and OLED panel makers.

• Scenario for a µLED display supply chain.

Everything You Always Wanted to Know About µLED Displays!

MicroLED Displays | Sample |

3

Biography & contact

EricVirey - Principal Analyst,Technology & Market, Sapphire & DisplayDr. Eric Virey serves as a Senior Market and Technology Analyst at Yole Développement (Yole), within the Photonic & Sensing & Display division. Eric isa daily contributor to the development of LED, OLED, and Displays activities, with a large collection of market and technology reports as well asmultiple custom consulting projects. Thanks to its deep technical knowledge and industrial expertise, Eric has spoken in more than 30 industryconferences worldwide over the last 5 years. He has been interviewed and quoted by leading media over the world.

Previously Eric has held various R&D, engineering, manufacturing and business development positions with Fortune 500 Company Saint-Gobain inFrance and the United States.

Dr. EricVirey holds a Ph-D in Optoelectronics from the National Polytechnic Institute of Grenoble.

MicroLED Displays | Sample |

4

COMPANIES CITED IN THE REPORT

Aixtron (DE), Aledia (FR), Allos Semiconductor (DE), AMEC (CN), Apple (US), AUO (TW), BOE (CN), CEA-LETI (FR), CIOMP (CN), Columbia

University (US), Cooledge (CA), Cree (US), CSOT (CN), eLux (US), eMagin (US), Epistar (TW), Epson (JP), Facebook (US), Foxconn (TW),

Fraunhofer Institute (DE), glō (SE), GlobalFoundries (US), Goertek (CN), Google (US), Hiphoton (TW), HKUST (HK), HTC (TW), Ignis (CA),

InfiniLED (UK), Intel (US), ITRI (TW), Jay Bird Display (HK), Kansas State University (US), KIMM (KR), Kookmin U. (KR), Kopin (US), LG (KR),

LightWave Photonics Inc (US), Lumens (KR), Lumiode (US), LuxVue (US), Metavision (US), Microsoft (US), Mikro Mesa (TW), mLED (UK), MIT

(US), NAMI (HK), Nanosys (US), NCTU (TW), Nichia (JP), Nth Degree (US), NuFlare (JP), Oculus (US), Optovate (UK), Osterhout Design Group

(US), Osram (DE), Ostendo (US), PlayNitride (TW), PSI Co (KR), QMAT (US), Rohinni (US), Saitama University (JP), Samsung (KR), Sanan (CN),

SelfArray (US), Semprius (US), Smart Equipment Technology (FR), Seoul Semiconductor (KR), Sharp (JP), Sony (JP), Strathclyde University (UK),

SUSTech (CN), Sun Yat-sen University (TW), Sxaymiq Technologies (US), Tesoro (US), Texas Tech (US), Tianma (CN), TSMC (TW), Tyndall National

Institute (IE), Uniqarta (US), U. Of Hong Kong (HK), U. of Illinois (US), Veeco (US), VerLASE (US), V-Technology (JP), VueReal (CA), Vuzix (US), X-

Celeprint (IE)…and more.

MicroLED Displays | Sample |

5

TABLE OF CONTENTS

• Executive summary p10

• Introduction to microLED displays p51

• Definition and history

• What is a microLED display?

• Comparisons with LCD and OLED

• Assembly

• Display structure

• SWOT analysis

• MicroLED display manufacturing yields p63

• Overview

• Individual die testing.

• KGD mapping and individual transfer

• Transfer fields and interposers

• Defect management strategies

• Yield roadmap

• Redundancy

• Conclusions

• MicroLED epitaxy (FE Level 0) p79

• Wafer size

• Wavelength homogeneity

• Epitaxy defects

• Cycle time and thickness

• Blue shift

• Wafer flatness

• GaN-based red chips

• Conclusions and impact on supply chain

• Chip manufacturing and singulation (FE Level 1) p96

• MicroLED singulation p97

• Impact on cost related to the epiwafer

• Illustrations

• MicroLED efficiency p104

• LED and microLED efficiency

• Development thrust areas

• Current confinement structures

• Status

• MicroLED chip manufacturing p112

• Example of process flow – Apple 6 masks

• Lithography

• Fab types comparison: infrastructure & equipment

• MicroLED in CMOS fabs

• Transfer and assembly technologies p124

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6

TABLE OF CONTENTS

• Overview p125

• Major types and key attributes of transfer processes

• Challenges

• Pick and place processes p129

• Sequence and challenges

• Transfer sequences

• Transfer arrayVs. display pixel pitch

• Throughput and cost drivers

• Direct transfer vs. interposer

• Interposer and yields

• Other use of interposers.

• Example (X-CeLeprint)

• Continuous/ semi-continuous assembly p141

• Overview

• Laser-based sequential transfer

• QMAT-TESORO

• Uniqarta

• GLO

• Optovate

• Self assembly p150

• Fluidic self assembly

• Example: Sharp/ELUX

• Summary p154

• Intellectual property landscape

• Selectivity

• Major transfer processes: most mature

• Transfer processes: others

• Conclusion

• Transfer and assembly equipment p165

• Introduction

• Traditional single chip tools

• Assembly environment

• Specific challenge for mass transfer

• Bulk microLED arrays p171

• Full array level microdisplay manufacturing.

• Hybridization & bonding process

• Wafer level bonding

• Monolithic integration of LTPS TFT: lumiode

• 3D integration: Ostendo

• Yields and costs

• Color generation in bulk arrays

MicroLED Displays | Sample |

7

TABLE OF CONTENTS

• Pixel repair p183

• Emitter redundancy

• Example of repair strategies

• Defect management strategies

• Light extraction and beam shaping p189

• Optical crosstalk

• Emission pattern, viewing angle and power consumption

• Emission pattern and color mixing

• Die-level light management

• Array-level beam shaping

• Color conversion p204

• Overview

• Phosphors

• Quantum dots

• Flux requirements

• Patterning and deposition

• Backplanes and pixel driving p214

• Introduction

• Channel materials for microLED displays

• Mobility vs display specifications

• Stability and signal distortion

• Pixel density

• Analog driving: microLED driving regime

• MicroLED-specific challenges

• Illustration: 75” 4K TV, QHD smartphone

• Digital driving: introduction

• Digital driving: benefits & challenges

• Hybrid driving

• AnalogVs digital: summary

• TFT versus discrete micro IC.

• Cost zspects

• Cost reduction path

• Conclusions

• Economics of microLED – cost down paths p240

• Baseline hypothesis and sensitivity

• Television p247

• Cost target and price elasticity

• 75” TV panel assembly strategies

• Yield impact

• Very large panels

• Benefit of sequential transfer

• Interposers

• Die size

• Cost-down path

MicroLED Displays | Sample |

8

TABLE OF CONTENTS

• Smartphones p265

• Cost target

• Illustration: 6” QHD phone panel

• Key outputs

• Die size optimization

• Interposers

• Applications and markets for microLED displays p277

• MicroLED attributes vs application requirement

• Application roadmap

• SWOT per application

• Key hypothesis for equipment forecast

• 2017-2027 microLED adoption forecast

• AR, MR andVR p284

• The reality-to-virtual-reality continuum.

• Market volume headset forecasts forVR and aR

• MicroLED adoption and volume forecast

• Head up displays

• Smartwatches p290

• Smartwatch volume forecast

• MicroLED Adoption and volume forecast

• Smartphones p294

• Who can afford a smartphone?

• Smartphone panel volume forecast

• Mobile phones: display for differentiation

• Foldable smartphones

• MicroLED adoption and volume forecast

• TVs p301

• The “Better Pixel”

• Resolution

• TV panel forecast

• 8K adoption

• MicroLED adoption and panel volume forecast

• Others: tablets, laptops, monitors p310

• Overview

• Tablets

• Laptop and convertibles

• Desktop monitors

• Wafer and equipment forecast p315

• Epiwafer

• MOCVD

• Transfer equipment

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9

TABLE OF CONTENTS

• Competitive landscape p322

• Time evolution of patent publications

• Leading patent applicants

• What happened In the last 18 months

• Time evolution of patent applications per company

• Breakdown by company headquarters

• Positioning of established panel makers

• Breakdown by company type

• Supply chain p332

• Overview

• Capex aspects

• Supply chain requirement

• Front END (LED Manufacturing)

• Back end: backplane, assembly and module.

• Supply chain scenarios

• Intellectual property

• Conclusion

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10

SCOPE OF THE REPORT

This report provides an

extensive review of µLED display technologies and

potential applications as

well as the competitive

landscape and key players.

Smartwatches and

wearables

Virtual reality

Large video

displays

TV

Smartphones

Laptops and

convertibles

Automotive HUD

Augmented/Mixed

Reality

LG

Samsung

HP

BMW

Microsoft

Oculus

Apple

Tablets

Acer

The report does not cover

non-display applications of

µLED: AC-LEDs, LiFi,

Optogenetics, Lithography,

lighting…

MicroLED TV prototype (Sony, CES 2012)

Contrary to the 2017

edition, this report does not

cover applications in large

LED videowalls: those will be

discussed extensively in our

upcoming report on

miniLED applications and

technologies

MicroLED Displays | Sample |

11

SCOPE OF THE REPORTC

hip

s

(to

scale

)

Packages

(No

t to

scale

)

MicroLED Displays | Sample |

12

WHO SHOULD BE INTERESTED IN THIS REPORT

• LED supply chain: sapphire makers, MOCVD

suppliers, epi-houses.

• Understand the µLED display opportunity

• What does it entail for the LED supply?

• What are the technical challenges?

• How can my company participate in this emerging

opportunity?

• Who should we partner with?

• R&D Organizations and Universities

• Understand the market potential of your

technologies for this emerging market

• Identify the best candidates for collaboration and

technology transfer.

• OEMs/ODMs

• What are the potential benefits of µLED displays?

• Are they a threat or an opportunity for my

products?

• When will they be ready

• Should I get involved in the supply chain.

• Display Makers and supply chain

• Hype versus reality: what is the status of µLEDdisplays? What can we expect in the nearfuture?

• Are they a threat to my LCD and OLEDinvestments?

• Which display applications and markets canµLED displays address? A detailed roadmap.

• Find the right partner: detailed mapping of theµLED ecosystem and supply chain

• OSAT and foundries

• Are µLED a new opportunity for mycompany?

• Venture capital, financial and strategicinvestors.

• Hype versus reality. Understand thetechnology and the real potential.

• How is the supply chain shaping up?

• Identify the key players and potentialinvestment targets.

• Could µLED hurt my existing investments?

MicroLED Displays | Sample |

13

MAJOR MANUFACTURING TECHNOLOGY BRICKS

Pixel AssemblySubstrate Defect

Management

Pixel

Driving

100 - 150 mm

Sapphire

200 - 300 mm

Silicon

Single wafer

Multi wafer

Monolithic

Arrays

Massively

Parallel Pick

and Place

Semi-

continuous

Pixel

Redundancy

Pixel Repair

Si-

CMOS

TFT

Epitaxy & wafer

processing

• Hybridization

• Monolithic

Integration

• Electrostatic

• Electromagnetic

• Magnetic

• Adhesive…

• Fluidic assembly

• Film cartridges

• Flexographic

• Laser…

• LTPS

• Oxide

• Pick and replace

• Add repair

Epi

Mask

Aligners

Steppers

Litho

Repair

Contactless

Optical (PL)

Contactless

Electrical (EL)

Test

Bac

kpla

nes

Micro

Drivers

ColorLight Extraction

& shaping

Quantum

dots

Nano-

phosphor

Optically

pumped

quantum

wells

Direct

RGB LED

Colo

r co

nve

rsio

n

Die Level

(shaping,

mirrors)

External optics

Testing and

binning

Die-level

(KGD map)

Transfer

field level

Binning

Interposers

with KGD

KGD transfer

only [1]

[1]: need Known Good Die (KGD) map and addressable transfer process

Pixel bank

level (mirrors,

black matrix)

MicroLED Displays | Sample |

14

MicroLED DISPLAYS TECHNOLOGY EVOLUTION

Cree:

Micro-led arrays with

enhanced light extraction University of Strathclyde:

active matrix and color

conversion

HKUST: Full color with

phosphor conversion

LETI: Monochrome active

matrix > 2000 PPI

Ostendo:

full RGB 5000 PPI

Sony:

55” FHD

microLED TV at

2012 CES

MicroLED Displays | Sample |

15

ASSEMBLY

• The art of making µLED displays consists in processing a bulk LED substrate into an array of micro-LEDs which are

poised for pick up and transfer to a receiving substrate for integration into heterogeneously integrated system: the

display (which integrates, LEDs, transistors, optics, etc.). Epiwafers can accommodate 100’s of millions of µLED chips

compared to 1000’s with traditional LEDs.

• The micro-LEDs can be picked up and transferred individually, in groups, or as the entire array of 100,000’s of

µLEDs:

Monolithic integration of µLED arrays is preferred for the realization

of displays with high pixel

densities.

Pixel Per Inch

0 1000 2000 3000 4000

Si-CMOS Backplane

µLED array

Backplane

Hybridization

Low to Mid Pixel density: Pick and Place High Pixel Density: Monolithic Array Integration

OculusOppo

AppleSamsung

Projection micro display

Microsoft

AR/MRTV Wearable Smartphones VRLaptop/

Tablets

LTPS or Oxide TFT backplane

µLED epiwafer

µLED epiwafer

MicroLED Displays | Sample |

16

TRANSFER FIELDS AND INTERPOSERS

Yield loss = hatched surfaces +

transfer fields where the number n

of KBD and point defects exceeds

specification.

Transfer field with ≥ n point defect

are eliminated.Transfer directly to backplane or create interposers with transfer fields

that are within the wavelength bin and ≤ n KBD/point defects.

Some bad die are transferred and need to be repaired.

Epiwafer wavelength homogeneity

and defective die map.

If individual functional die testing

not available, use PL + traditional

surface inspection.Interposer with only good

transfer fields

MicroLED Displays | Sample |

17

DEFECT DENSITY

For the smallest die required for TV or smartphone applications, the largest allowable defect size will fall below 1 µm

• The actual specification and the maximum acceptable defect

size will depend on:

• The die size

• The chip structure

• The yield and defect management strategy adopted by each

manufacturer: driven by cost of ownership (cost of increasing

yield vs managing defects)

• A plot of a simple Murphy defect density model with a

triangular distribution shows that to get 90% of 1x1 cm2

transfer fields defect free, the defect density needs be ≤

0.1/cm2.

• For 2x2 cm2 transfer fields, the requirement increases to

<0.03 defect/cm2. Larger stamps quickly lead to unacceptable

wafer yield losses and/or unrealistic demands on defect

density and can only be envisioned if efficient downstream

yield management and repair techniques can be deployed.

• Regarding defect size, abiding by the 1/5th rule used in

semiconductor manufacturing, a 3x3 µm µLED will likely

require ~1 µm features or less, which could be bringing the

acceptable defect size to about 0.2 um. Even if more relaxed

targets are acceptable, 0.5-0.8 µm seems like a reasonable

range.

Above: plot of a simple Murphy defect density model with a

triangular distribution. This model is widely used in the

semiconductor industry for estimating the effect of process defect

density. More complex models should be used to account from

the fact that defects often ten d to appear in clusters etc.

MicroLED Displays | Sample |

18

Substrate

n-GaN

MQWp-GaN

Mask#5: opening of the sacrificial layer

(about 1 x 1 µm), dry etching (CF4 or NF3) or wet

etching (more likely to produce the overhang)

Substrate

n-GaN

MQWp-GaN

Stabilization layer deposition:

Spin coating of thermosetting material such as

benzocyclobutene (BCP) + adhesion layer (e.g.: AP3000

from Dow chemical). Cured to 70% so it doesn’t reflow

Carrier wafer bonding

(Semi-cured stabilization layer provides sufficient

adhesion)

Substrate

n-GaN

MQWp-GaN

Carrier Substrate

n-GaN

MQWp-GaN

Carrier Substrate

Epitaxial substrate removal (LLO)

n-GaNMQW

p-GaN

Carrier Substrate

n-GaN dry etching or CMP

n-GaNMQW

p-GaN

Carrier Substrate

Mask #6: deposition and patterning of ohmic

contacts (NiAu or NiAl, typ. 50 Å thick)

Annealing at 320 deg. C. for 10 minutes

Ohmic contacts

n-GaNMQW

p-GaN

Carrier Substrate

ITO deposition (typ. 600 Å thick)

n-GaNMQW

p-GaN

Carrier Substrate

Planarization resist

n-GaNMQW

p-GaN

Carrier Substrate

Resist is stripped (wet etching or plasma ashing) until the ITO and the

passivation layers are removed from the bottom of the large mesa,

exposing the sacrificial layers. Residual resist is then fully stripped

EXAMPLE OF PROCESS FLOW – APPLE 6 MASKS

MicroLED Displays | Sample |

19

Marginal

CHIP MANUFACTURING: SUMMARY

µLED displays might require a paradigm shift

from traditional LED

manufacturing to silicon

CMOS-type of environment

and tools.

Plasma Etching

Lithography

Clean Room

Traditional LED

ManufacturingµLED Display Manufacturing

Sidewall quality not critical to LED

efficiency. High tolerance for particlesxxxxxxxxxxxx

Mask aligners, single shot xxxxxxxxxxxx

Class 10,000 and above xxxxxxxxxx

Laser Lift Off(sapphire-based platform)

xxxxxxxxxxxx

Wafer Bonding Marginal xxxxxxxxxxxx

Substrate

platformSapphire dominant

Little opportunity for Siliconxxxxxxxxxxx

Testing PL + EL Probe testing xxxxxxxxxxxxx

Paradigm

shift?

MicroLED Displays | Sample |

20

KEY ATTRIBUTES OF TRANSFER PROCESSES

Throughput

• Cycle time

• Number of die per cycle

Yields

• Pick up

• Drop off

• Assembly/Inter-connect

Capability

• Die size

• Die Shape

• Placement accuracy

KGD compatibility

• Individual die addressability

• Interfacing with inspection/test equipment –KGD map

Intellectual Property

• Freedom of exploitation

• Licensing

Cost

• Equipment cost

• Footprint

• Consumables (transfer stamp etc.)

Cost of Ownership

MicroLED Displays | Sample |

21

DIRECT TRANSFER VS. INTERPOSER

Red, Green, Blue LED

EpiwafersTransistor backplane (TFT, direct hybridization on Silicon…)

Interposers (intermediate carriers) or various forms of pixel “banks”

can be used for:- Binning / yield management purpose

- Intermediate pitch step up

- Pre-assembly of RGB or RGB + driver IC sub-assembly

MicroLED Displays | Sample |

22

TRANSFER AND ASSEMBLY

• As of Q2-2018, massively parallel pick and place methods are the

most mature, lead by X-Celeprint and Apple with passive (PDMS

stamps) and active (MEMS) transfer head respectively. Various other

companies have demonstrated display prototypes assembled with

similar technologies: XXX, XXX, XXX and probably more who

haven’t publically shown their work.

• Semi-continuous or self assembly processes have also been pitched

and/or demonstrated by a variety of companies including Vuereal

and eLux.

• Semi-continuous process reduce the cycle time by reducing or

eliminating the X-Y print-head motion steps between donor and

receiver substrate (see discussion in the “Cost Analysis” section of

this report).

• Laser transfer potentially offers compelling benefits such as high

throughput and compatibility with KGD yield management

strategies. But development is less advanced than massively parallel

P&P. To our knowledge, glō is so far the only company to have

realized display prototypes using the concept.

Massively parallel P&P technologies are the most mature.

Massively Parallel P&P Leading companies

Continuous/Semi-Continuous and self

assembly

Laser Processes

MicroLED Displays | Sample |

23

TRANSFER PROCESSES: MOST MATURExxxxxx xxxxxxx xxxxxxxxxx xxxxxxxx

Type • Pick & Place • Pick & Place • Self Assembly • Sequential

Sub-type • xxxxx • xxxxxx • xxxxxx • xxxxxx

Cycle time • 10-15s (est) • 30s, target 10s • Continuous • Continuous

Scalability• Small to mid size stamps (1-2”?)

• Probably challenging to scale up (

• Up to XX cm stamp demonstrated but

unknown impact on yield, placement

accuracy and cycle time

• Current work on XXX tool delivers

50M die/hr throughput.• Wafer size (up to 6”)

Placement

accuracy• ? • ±1.5µm 3 • ~ ± 2.5 µm (determined by xxxxx) • ±1.0 µm

Constrain on

die structure

• Flat top surface required

• Horizontal or vertical

• Flat top surface required

• Tether and anchors

• Horizontal or vertical

• Horizontal LED

• Circular geometry preferred. • Vertical LEDs

Yield status

(Q12018)• ? • 3N to 4N • 2N8 • > 4N

Die Size • As small as 3 µm • As small as 3 µm• As small as 10 µm but perform

better above 20-40 µm• 2 to 20 µm

Active stamp [2] • xxxxxxxx • No • NA • Yes. Placement selectivity

KGD

management• xxxx

• Via additional step to eject bad die from

the stamp.

• Die binned/sorted upstream (laser

lift off)• Yes (placement selectivity)

Strengths • Possible high accuracy• Low cost stamp

• Possibly scalable• Potentially very cost-effective • KGD management, throughput

Limitations• High cost stamps

• Scalability (large areas?)

• Not addressable

• Die size can affect cycle time

• Best for low PPI (0.2 to 1 mm pitch)

• Large die

• Need transparent substrate

(sapphire or interposer)

MicroLED Displays | Sample |

24

HYBRIDIZATION: EXAMPLES OF BONDING PROCESS

Hybrid bonding: Cu + oxide

Hybrid bonding: Cu + Polymer

Microtube bonding

Hybridized active-matrix GaN 873 x

500 pixel microdisplay at 10 μm pitch

using microtube bonding (LETI)

MicroLED Displays | Sample |

25

EMISSION PATTERN AND COLOR MIXING

• If the red, green and blue emitters have different light emission patterns, the color calibration performed at one angle (typically

perpendicular to the display plane) will shift when viewed off-angle as the relative intensities of R,G,B viewed in that given

direction will changes.

• This issue often occurs when the red emitter is formed from a different material (InGaAlP) and has a different structure than

the green and blue die (InGaN).

[1]:

30

60

90

-30

-60

-90

0

Hypothetical beam pattern of Red, Blue and Green emitters (not actual, illustration purpose):

the relative intensity of the red green and blue emitters at 0 degree and 30 or 60 degrees varies,

resulting in a shift of color balance at those different angles.

(Source: Yole Development)

MicroLED Displays | Sample |

26

FLUX REQUIREMENTS

Max Display

Brightness

(Cd/m2)

Pixel

Density

(PPI)

LED Chip

Size

Optical Flux at

LED surface [1]

(W/cm2)

Driving

current

(A/cm2)

TV 4k 5000 80 X µm xxx-xxx xxx-xxx

TV 8K 5000 100 X µm xxx-xxx xxx-xxx

Wearable 1500 300 X µm xxx-xxx xxx-xxx

Smartphone 1500 500 X µm xxx-xxx xxx-xxx

RGB AR/MR

(State of the art)5,000 3000 X um xxx-xxx xxx-xxx

RGB AR/MR

(Goal)500,000 5000 X µm xxx-xxx xxx-xxx

Likelihood

that

quantum

dots color

conversion

be

adopted

[1]: for all applications, it is assumed that the downconverter is deposited directly at the surface of the pixel (discussion next page). In addition, an overall

optical efficiency of 60% for the red and green pixels and 80% for blue (unconverted) was assumed.

[2]: optimal efficiency with GaN LED is achieved with current density in the 1-10 A/cm2 range. For applications where the required driving current is

significantly below that range, the LED will likely be driven in pulsed mode, ie at higher current density with a low duty cycle

MicroLED Displays | Sample |

27

INTRODUCTION

• The different functions required for active display

driving are shared between discrete ICs positioned

at the edges or behind the panel and Thin Film

Transistor (TFT) circuitry deposited directly onto

the display substrate (=backplane).

• Emissive displays such as OLED or microLED are

current-driven. The simplest mode of operation for

the TFT circuit requires 2 transistors and 1 capacitor

(2T1C).

• However, very small variations in current result in

visible brightness differences visible by the human

eye. The 2T1C simple design doesn’t compensate for

pixel to pixel variations in the threshold voltage,

carrier mobility, or series resistance that result from

TFT processing or from variability in the emitters

(LED or OLED)

• Compensation schemes relying on a larger number

of transistors per pixel (up to 7 in some designs) are

therefore used. The complexity of the TFT however

can be reduced in some designs by offloading some

of the compensation function onto external ICs [1].

Driving emissive displays (OLED, µLED) requires complex compensation schemes

Row Driver

Column

Driver

Timing

Controller

Gamma circuit

Test circuits

etc.

Power

TFT

Pixels

Simple, non compensated pixel circuit

with 2 transistors [1]

Example of a 4 transistor

compensated circuit [1]

[1]: Source: “AM backplane for AMOLED”; Min-Koo Han, Proc. of ASID ’06,

Simple block diagram for display driving

Other circuits

[1]: LG OLED TV for example are driven by 2T1C circuit with compensation performed by external ICsMicroLED Displays | Sample |

28

ILLUSTRATION: 75” 4K TV

• MicroLED makers usually strive to:

• Use the smallest die possible to minimize cost.

• Operate close to peak efficiency in the typical brightness

range of the display.

• For a 75” 4K TV, a 1000 Nits brightness can be

achieved with XX µm die operated near peak

efficiency at XX A/cm2 (blue and green chips).

• At this average brightness level, the current per chip is

XX µA.

• For the lowest and highest brightness levels, the

current range between XX nA and XX nA

Panel characteristics• 75 Inch diagonal

• 4K resolution (3840x2160)

Die size 5 x 5 um

Peak Brightness 3000 nits

Average Brightness 1000 nits

Lowest brightness 3 nits

LED emission pattern Lambertian (120 ° APEX angle)

Optical efficiency (Photon losses in

pixel cavity, external optic etc..)80%

Display

BrightnessCurrent Density Current EQE

Low (3 Nits) XXX A/cm2 XX µA 14%

Average (1000

Nits)XXX A/cm2 XX µA 22%

Peak (3000

Nits)XXX A/cm2 XX µA 19%

MicroLED Displays | Sample |

20%

10%

29

TFT VERSUS DISCRETE MICRO IC.

• Another debate is whether TFT used for OLED panel driving (LTPS for smartphones and wearable, Oxide for TVs) are

suitable for microLED.

• Due to the non linear characteristics of microLED, the different ranges of operating currents and the added complexity

of using 2 types of semiconductors in RGB solutions (InGaN and InGaAlP), driving circuits will likely be more complex

than OLED and integration with traditional TFT be more challenging.

• Apple/Luxvue and X-Celeprint have both suggested using discrete Si-Based microdrivers to drive the pixels. X-

Celeprint has demonstrated multiple display prototypes using this concept.

Sub pixel with 2x µLED redundancy

IC driver

A µLED display where discrete ICs

positioned on the front face drives groups of

12 subpixels featuring a 2x redundancy.

(Source: LuxVue patent US 9,318,475)

Patent XXX from XXX [1]

[1]: we believe that XXX is a company created by Apple and under which name its has been filing its microLED patents after 2015

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30

COST ANALYSIS: INTRODUCTION

• At the current stage of maturation of the

industry, there are still many plausible technology

and process choices. This precludes

comprehensive cost modeling.

• However, there are some fundamentals that

anchor all those processes: alignment dominates

assembly cycle times, die size can’t get infinitely

small, and epitaxy has already been through a

more than 20 years cost reduction curve.

• Basic cost analysis can therefore be performed

to narrow the process space to a more

economically realistic window.

• The objective of this section is to provide such

analyses for the major building blocks and cost

contributors in to order validate the fundamental

economics of microLED displays and identify

credible cost-down paths and targets.

• The effort is focused on the 2 high volume

applications where microLEDs have the most

potential to both disrupt the existing display

chain and generate large, new business

opportunities:TV and Smartphones.

Many unknowns in term of technological choices prevent detailed cost modeling but a high level analysis can still provide valuable insights

By defining cost targets and performing a basic cost analysis within realistic

process parameters, it is possibly to narrow the size of the process windows

compatible with economical targets for each application.

Current microLED process window

Realistic process window narrowed

down with high level cost analyses

Product and

volume

manufacturing

-compatible

process

window

Die

: Si

ze, c

ost,

redundancy

, yie

ld…

Assembly:Cycle time, yield, stamp size, sequential/continuous, self assembly, redundancy…

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31

75” TV PANEL ASSEMBLY STRATEGIES

75” TV Panel

• 18 transfer field per wafer

• 72% of the wafer surface used

12.73 x 12.73 mm2 transfer stamps

• 86 transfer fields per wafer

• 86% of the wafer surface used 9694 transfer cycle per color

25.45 x 25.45 mm2 transfer stamps

101.8 x 101.8 mm2 transfer stamps

• 1 transfer field per wafer

• 64% of the wafer surface used

2442 transfer cycle per color

170 transfer cycle per color

Drawings approximately to scale

We first consider the following 3 assembly scenario with increasing transfer stamp sizes and no interposers:

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32

SEQUENTIAL TRANSFER – 4N YIELD

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33

CAPEX

Investment to set up a microLED fab should be at least on par and most likely lower than that of an OLED or even Oxide TFT LCD Fab

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34

COST TARGET

• The microLED die +

assembly budget to strictly

match OLED by 2022 is

around ~$XX.

• If microLED can deliver

unique and desirable

features that no other

panel technologies can

offer (e.g.: sensing

functionalities, superior

and local brightness

adjustment, reduced

power draw etc.), this

cost budget could increase

up to $XX, after

budgeting for additional

cost related to those new

functionalities

(microsensors etc)

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35

MICROLED APPLICATION ROADMAP

Smartphone

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxx.

Smartwatch and wearables

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxx.

Tablets and laptop

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxx

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxx.

• Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.

2020 Longer term2022

High end TVs and monitors (4K, HDR)

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxx.

AR/MR HMDs

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxx.

• xxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxx.

Now

(2018)

Automotive HUD

• Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxxx.

Small pitch (<2mm)

large video displays.

• Brings significant

performance improvement

(contrast) and potential

cost reduction (eliminates

LED package)

• Large die OK (30 µm) but

low transfer efficiency.

• Available from Sony since

2017:

2023+

Other Automotive Displays

• xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxxxxxx

2024+

Virtual Reality

(VR)

• High cost.

• Limited benefits

vs OLED.

2021

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36

MICROLED TV PANEL VOLUME FORECAST

Distinguishing 8K is important since they feature 4x more microLED die than 4K panels

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37

BREAKDOWN BY COMPANY TYPE

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