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Material for Micro LED Technology

2 Merck Material for Micro LED Technology | 2017

Merck’s Advanced Materials for Micro LED Technology

Micro LED Technology Challenges

Source: LEDinside, January 2017

MO Precursor

Photoresist

QD-MaterialPhosphor

SOG, SOHG

Materials

Barrier Novel Binder

3

Merck Sigma Precursor (former Aldrich Hitech)

Main metal organic precursors in special containers (0,05-7,4kg)

Element Metalorganic source

Application

CVD Doping Oxide

Al Trimethylaluminuim (TMAL) ◎ ◎

InTrimethylindium (TMIN) ◎ ◎ ◎

Solution TMI (TMIS) ◎ ◎ ◎

Mg

Bis(cyclopentadienyl)magnesium (CPMG)

◎ ◎

Soultion CP2MG (CPMS) ◎ ◎

GaTrimethylgallium (TMGA) ◎

Triethylgallium (TEGA) ◎

ZnDimethylzinc (DMZN) ◎ ◎ ◎

Diethylzinc (DEZN) ◎ ◎ ◎

CCarbon tetrabromide (CBR4) ◎ ◎

Carbon trichlorobromide (BTCM) ◎ ◎

As Trimethylarsine (TMAS) ◎

P Tertiarybutylphosphine (TBPH) ◎

Key Benefits

• Lowest impurity/oxygen level

• World wide supply network

• Customer/OEM container design

• 100% material usage by using in-series connecting kit

Proven history in organometallics for the last30 years

Merck Material for Micro LED Technology | 2017



Particle measurement - Purge with high pressure of N2

190ml 400ml 930ml 1200ml 2780ml 5300ml

Par

ticl

e co

un

ts (

au)

Bubbler volume

After N2 purge

0.1μm 0.2μm 0.3μm 0.5μm 1.0μm

190ml 400ml 930ml 1200ml 2780ml 5300ml

Par

ticl

e co

un

ts (

au)

Bubbler volume

Before purge

0.1μm 0.2μm 0.3μm 0.5μm 1.0μm

Before purge After N2 purge

bubbler volume sensitive Non-sensitive

particles for 5L bubbler >11,000 <1

particles >1 μm Yes Zero

Particles must to be controlled in mass production of making advanced devices, like MicroLED.

4

Factor ~ 0.001

Moisture control

Bubbler (au)

Before treatment After treatment

Moisture trend of OM470

Before

Maximum moisture level >2000 ppb.

Larger bubbler size, higher moisture levels. (data not shown here)

After

Lower moisture (<200ppb)

Small STDEV

Not relative to bubbler size (up to 8L)

Bubbler wet cleaning

Bubbler dry cleaning Special

treatment

He leak check

5

He leak check

(Previous SOP)

(Current SOP)



6

LED Photoresist Line Up

Merck’s High Performance & Quality Photoresists for the LED Chip Process

120 mm FT

10 mm FT

Merck GXR for PSS process

− High etch resistance and wide DOF

− Further improved version GXR-601 M1

Merck Thick-Film PR for advanced applications

− e.g. Flip-Chip, Vertical Chip process

− Plating application

− Film thickness 5 ~ 120 mm

Merck SLD for ITO/SiO2 and MESA etch

− Versatile and high throughput

− Excellent adhesion

Merck nLOF, LOR for Metal Lift-Off

− High aspect ratio

Merck Negative-Tone PR (under development)

− Metal Lift-Off with undercut enhancement

− High-temperature resistance

10mm

5mm

5mm


7

Merck Thick Film Photo-resist

Product Line up ~20um


SOG Introduction

Transparent Dielectric: Silicon-Organic-Glass (SOG) Material

SOG coating: transparent planarization layers for thin-film transistor (TFT) backplanes in displays

before planarization

after planarization with SOG

SOG• Thermal durability (>350ºC)• Optical transparency (1h @ 300ºC)

• Curing >200ºC• Excellent planarization

• Si-based polymer material basis


LED Chip Periphery & PackagingPhoto-Structurable SOG Material

(1) Coating & Exposure

(2) Development

(3) Post Bake

10µm

5µ

m

SOG

No etching process needed

Key Benefits

3

2

1Highly transparent material ( 300°C)

Thermal durability ( 300°C)

Litho-type (i-line) saves process steps (features < 2mm)

Litho Process


LED Chip Periphery & PackagingPhoto-Structurable SOG Material

5µm

• FT: up to 3-8mm

• Feature size: down to 1.5mm

(i-line exposure)• Enabled structures:

- Lines & pillars- Trenches & holes

• Litho type:

- Positive tone- Negative tone

Curing conditions: 250°C


11

Transparency and Thermal Stability of SOG Material

High Thermal Stability

TGA: no weight loss up to 300°C

(after curing 60min@250°C)

60min @ 400°C

60min @ 450°C

Negative-tone SOG

High Optical Transparency

Transparency >99.8%@400nm after

high-temperature bake (1mm thickness)

Non-photosensitive SOG

Positive-tone SOG

Negative-tone SOG

Highly Transparent Dielectrics for Optical Applications

Tran

sm

itta

nce



Highly Transparent Dielectrics for Optical Applications

Lithographic SOG and SOHG (Hybrid) Material

Si-Based Polymer Hybrid with Organics

Litho Type POS NEG Non-PS* NEG*

Max. FilmThickness

~8 um ~3 um ~3 um ~10 um

Cure Temperature

>250°C >250°C >200°C 120-180°C

Thermal Stability

<350°C <400°C <400°C <250°C

• Opportunity: potential applications in the field of LED seen

• Light-sensitive versions: Aspect Ratio ~1:1 (g,h,i-line irradiation)

• Pure Si-polymer formulations are developed to accommodate a high-temperature process step (>280°C) such as thermal annealing

• Hybrid systems with reduced curing temperature and higher thickness (trade-off: thermal stability)

* Commercial product for FPD application.

10um dot

10um L/S

Permanent structures with SOHG materials

Permanent structures with SOG materials

13

Novel binder

Best solution for LED encapsulation

Material PropertyMethyl

Silicone

Phenyl

Silicone

Merck’s

Binder

Yellowing (heat & light

fastness)

Refractive Index

Barrier Properties

Pot-Life


14

Color stability at high driving current in a LED package

Merck‘s Novel Optical Binder: less color shift after 1.5A/1000hr test

➢ High-temperature stability ; stable than Phenyl-Silicone

Reliability data of Merck MRI Binder vs. Phenyl-Silicone.

Ratio of Binder : Phosphor (Merck isiphor® YYG 559 200) = 1:5 w/w.


Areas where Merck focuses

15

OLED OPVQuantum

Dot / Rod

Increasing barrier performance needed

Merck offers

advanced formulations

enabling coatable barrier film production

Barrier films protect against

oxygen and water

26Merck Material for Micro LED Technology | 2017

Barrier Formulations

Coating Drying Cure

Roll-to-roll Processing Polysilazane barrier formulations

Barrier Film

Oven UV

Coating

Barrier

film

Cure possible by

(A) VUV or(B) steam.



Silicon OxyNitride Film by UV Curing

N

S iSi

N

SiN

SiN

SiN

SiN

H SiSi

H

H

H

H

H

H

HH

HH

HH

H

H

Si

H

H

N

H

H UV cure (N2)

Conditions1. Material: AZ NL120A2. Tool:10mW/cm2 172nm excimer lamp3. Atmosphere: N2

N2 in N2 out

RotaryPump Eximer Lamp

Quartz window

N2 flow: 20 Liter / min.



18

Key take-aways

Barrier formulations

Variety of substrates –plastics or

glass

Thin layers –ideal for flexibility

Tuneable performance –adjust for your

end markets

Easy processing – does not

require vacuum


19

Single layer

QD or OPV requirements

Barrier

Plastic substrate

WVTR ~10-4g/m2/day

Multiple layers

OLED requirements

Plastic substrate

Barriers

WVTR <10-4g/m2/day

Barrier layer possibilities


Example performancecoated barrier films made in Merck’s

R&D lab.

More details available: NAX and NL systems: L. Prager et al Thin Solid Films 570 (2014) 87-95 and N. Satake, S. Kawato, Y. Ozaki & M. Kobayashi IDW’13, FLX4-3, pp1549-1550LB200 system: internal data20

Single layer, barrier material coated on

polyethylenenaphthalate (PEN) substrate

Water Vapor Transmission Rate (WVTR) was

determined at 40℃, 90% relative humidity

Formulation CureFilm

Thickness (nm)

WVTR (g/m2/day)

Reference PEN substrate - - 10

Barrier films

NAX120 Steam 800 10-2

NL120A UV 250 10-3

LB200 UV 200 10-4

21

Polysilazane formulations wet-coating (R2R) of barrier films.

Barrier performance tuneable to address different market needs, from QD barriers to OLED barriers

Formulations scaled-up and ready for market3

2

1

Barrier summary



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