Micro-Display - A New Generation for a Smarter World

Micro-Display - A New Generation for a Smarter World

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Description: Smart lighting and augmented reality call for high brightness & small pixels. LED can combine both  synergies between applications. GaN LED array technology provides high performance, low power consumption and high reliability for compact products.

Europe is well positioned to take advantage of the market thanks to actors of the comprehensive value chain. High brightness microdisplays required the integration of LED and transistors. There are three methods for integration.

 
Author: Sylvie Joly  | Visits: 245 | Page Views: 463
Domain:  High Tech 
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Contents:
A NEW GENERATION OF MICRO-DISPLAY
FOR A SMARTER WORLD
IDTechEX Berlin 2016| Sylvie JOLY|28th of April

FOR A SMARTER WORLD…

… BUT WHAT MAKES IT SMARTER ?
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 2

KEY REQUIREMENTS

Controlling Light

Ultra high
brightness

High resolution,
high brightness

Compactness,
high brightness
Fast response time

High resolution,
brightness &
contrast

Selective lighting

PIXELIZATION OF EMITTING LED
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 3

TOWARDS A NEW PARADIGM
LED can combine brightness and small pitch
Resolution
(Pixel density links to pixel pitch)

Low

104

General lighting

LED

103



102

 Control
 Selectivity

TV monitor




 Brightness
 Compactness
 Resolution

HUD
HuD 2.0

10

µ Projector

Smart Lighting

Augmented reality

Pixilation of LED
emitting area

HMD

High

Brightness

1
102

103

104

105

106

107

108

(cd/m²)

• Smart lighting and augmented reality call for high brightness &
small pixels
• LED can combine both  synergies between applications
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 4

AGENDA










Why Emissive LED array based on GaN
CEA-Leti positioning & platforms for Emissive LED array
Process @ CEA-Leti
Key achievements
Key challenges regarding applications
CEA-Leti Value Proposition
A road to highly scalable process
Conclusion & outlook

IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 5

WHY EMISSIVE LED ARRAY?
Today GaN for LED lighting
key benefits
Brightness, efficiency,…

• Demands for smart lighting



Color adjustment
Selective lighting

• High performance displays





Excellent optical properties
such as brightness and contrast
High power efficiency
for longer battery life
Fast response time

GaN for LED array
promise of benefits
Brightness, Reliability, response
time, view…

GaN LED array technology provides high performance, low
power consumption and high reliability for compact products
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 6

STATE OF THE ART
Europe is well positioned to take advantage on the market
thanks to actors of the comprehensive value chain

US
Europe
ASIA
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 7

WAYS TO GET BETTER PERFORMANCE

• High brightness microdisplays required the integration of LED and
transistors. There are three methods for integration:
Single wafer
for LED and TFT

Multi-wafer process

3D integration of GaN LEDs

LED array Chip
Thin film transistor
LED array Chip



LED process first
Transistor integrated
on LED wafer.

Silicon CMOS chip






LED and transistors
fabricated separately
Chip level assembly
Use foundry facilities




Simple process
High resolution
Low resolution (high pitch) Price for mass production

Silicon foundry
facilities
Direct bonding
LED post process

Ultra-high resolution
High scalability

LETI positioning
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 8

CEA-LETI POSITIONING & PLATFORMS FOR EMISSIVE LED
ARRAY
Research
programs on
OLED for
display &
lighting

Research
programs on LED
for lighting

Active matrix
Design

COMPONENTS
&
SYSTEMS

3D
Integration
&
packaging

Long experience
in heterogeneous
integration SI
on II-V & II-VI

MINIATURIZATION
TECHNOLOGIES

IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 9

PROCESS @ CEA-LETI

GaN wafer &
Diodes
-

-

Si Active matrix &
interconnection -

Epitaxial growth of
LED layers on
sapphire or other
substrates
Pixellization of LEDs
arrays

-

IC silicon active
matrix for LED driving
10µm-pitch or less
connectors

Hybridization
3D heterogeneous
integration of LED
arrays on CMOS
active-matrix

Electro-optic
testing
-

Light emission and
testing

IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 10

KEY ACHIEVEMENTS

Monolithic LED
arrays
very small pitch
(10µm with 4µm
inter-pitch)

High brightness
>106 cd/m2 in blue
up to 107 cd/m2 in
green

Good efficiency
wall-plug
efficiency
(extraction
limitation)

Towards color
QDs conversion

IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 11

DEMONSTRATOR ROADMAP

2014

2015

2016
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 12

KEY APPLICATION CHALLENGES

1. GaN pixellization



< 5µm for HMD, µprojector
10µm to 30µm for lighting or HuD

2. Hybridization



Standard for lighting
Very small pitch for HMD & Picoprojector

3. Color


Mandatory for all applications

4. High current density,
energy dissipation



For lighting applications

5. µLED assembly


For large size display

… for mass production cost effectiveness
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 13

CEA-LETI VALUE PROPOSITION (1/2)

• GaN pixellization: small
number of technological
steps:




Leti Process know-how
Pitch and Size reduction
(down to ~1 µm)

• Hybridization routes



Short-term: micro-tubes
down to 5µm
Mid-term monolithic 3D
integration down to 1µm

3D
integration

Disruptive
technology

IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 14

CEA-LETI VALUE PROPOSITION (2/2)

• Color



Short-term: QD color conversion
Mid-term: Advanced epitaxy
selective area growth

• High current & energy dissipation




Simulation
Characterization: hot spot spreading
in T° and current
µLED lifetime calculation
for Failure control & modeling

IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 15

CEA-LETI ‘S TECHNOLOGY POSITIONING
Scalability of
the
technology**

High

No existing high resolution
Low-cost / high volume
process for ultra-high
brightness display

Stand process.
on GaN wafer

Stand. led
On GaN
Flip.chip

& flip-chip
Colors tunable

Correct

CEA-Leti (First
demo)

Univ. Texas

ITRI

Univ.
HongKong

CEA-Leti: Potential
of the technology

Monolithic tech.
on GaN wafer

& TFT.

Complex
process
color

Poor

50

20

10

5

Pixel pitch*
µm

*A low pixel pitch allow high resolution and compact micro-display
** technology able to be compatible with high volume markets
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 16

A ROAD TO HIGHLY SCALABLE PROCESS
Augmented reality HMD
Professional & consumer

Color
Pixel density : 2µm pitch
Super High brightness 1x105Cd/m2cd/m2)
High resolution 1920x1080

 resolution
Cost 
Color
Pixel density : 5µm pitch
High brightness 1x104Cd/m2
Resolution : 106 pixels

Toward higher display
size

Large Screens
µLED Direct
Emission
displays
Color
Pixel density: 30µm
High brightness 1x104Cd/m2

Augmented reality HuD & projection
 Resolution
Color

Color
Pixel density : 10 µm pitch
High brightness ~3-5x104Cd/m2
~1000x1000

Smart lighting &
automotive glare free
Monochrome
10µm pitch
800x500
105Cd/m2 in blue green or red

Short-term

 Current densities

Monochrome
30 µm pitch
800x500
107 Cd/m2 in blue, green or red

Mid-term

Time
Long-term
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 17

CONCLUSION & OUTLOOK

• Nomadic information, smart lighting, wearable require innovation
and generate market opportunities for LED arrays

• Emissive µLED array is a good technology for high performances :
more pixels, more brightness, better Image Quality, better intensity
and color control at lower cost

• Europe is today well positioned on all the value chain,
from materials to systems

• CEA-LETI is your partner for applications development:






Full process platforms for 3-5 materials
Proven µLED array technology
Background in embedded electronics and active matrix
Background in report/hybridization technologies
And also: IoT, RF, etc.
IDTechEX Berlin 2016| Sylvie JOLY|28th of April | 18

Thank you for your
attention
Feel free to contact us

Sylvie Joly
Display Program Manager
Sylvie-j.joly@cea.fr
+33 438 783 946
+33 645 150 298
Leti, technology research institute
Commissariat à l’énergie atomique et aux énergies alternatives
Minatec Campus | 17 rue des Martyrs | 38054 Grenoble Cedex | France
www.leti.fr