[1.9] AMOLED 공정

1.9.1. Introduction

1.9.2. OLED Materials

1.9.3. Patterning Process

1.9.4. Process Equipments

OLED : Organic Light Emitting Diode

Small Molecule (저분자) Evaporation

Polymer (고분자) Solution Process (Ink Jet Printing)

Fluorescence (형광)

Phosphorescence (인광)

Bottom Emission

Top Emission

Passive Matrix

Active Matrix

발광 방향

구동 방식

재료의 발광 메카니즘

재료 및 공정

Organic EL : Organic Electroluminescent

3

Substrate

rigid

flexible

Driving

active

passive

Material

Small molecule

polymer

hybrid top emission

bottom emission

Light output

Encapsulation

solid

hermetic

Device structure

Single hetero

Double hetero

ETL/EmL

HTL

HTL

EmL

ETL

RGB generation

RGB

Down conversion

White light

EL R G B

B G R

B B B B→R B→G B→B

EL

CCM

B G R

EL

CF W→R W→G W→B

W

B G R

W W

Technological elements of OLED production

4

Device Structures (Small Molecule)

Glass Substrate

Metal cathode

Electron transport layer (ETL) Emission layer (EML)

Hole transport layer (HTL) Anode (transparent electrode)

Organic

Layers

전자 수송층 (ETL)

발광층 (EML) 정공

수송층 (HTL)

양극 (투명전극, ITO 등)

음극 (낮은 일함수 금속, Ca, Al:Li, Mg:Ag,등)

- 전자

정공

+

- +

두께: 100 ~ 200 nm

Exciton

1) Carrier Injection

2) Carrier Transport

3) Electron-hole recombination

and exciton formation

4) recombination of excitons

5

Actual Structure of OLED • Additional layer for improved efficiency

– Injection Layer • Reduces the injection barrier between the metal electrode and the organic

layer – Transport Layer

• Transports electron and hole to the emission zone

• Thickness: ~ 1000A • White OLED

– Consists of 2 or 3 layers of light-emitting layers (EML)

Cathode

Anode

HIL

HTL

ETL

EIL

Cathode

Anode

HIL

HTL

G-EML

ETL

EIL

R-EML

B-EML

RGB OLED White OLED

~1000A G-EML B-EML R-EML

6

Bottom vs Top Emission Bottom Emission Top Emission OLED Mode

Structure

Aperture

TFT Glass TFT Glass

• Low • High

Encapsulation • Simple • Large choice of material

• Complex • Transparent Getter • Transparent Cathode

High Current • Easy

• Low Resistance • Difficult

• High Resistance

7

Patterning Process

for

Small Molecule OLED

on Small Glass

8

OLED Process Flow

Encapsulation (Dispensing, UV rad.)

Encap can/glass loading

Encap can/glass cleaning

Desiccant

O2 plasma treatment

R, G, B deposition

HIL, HTL deposition

Cathode deposition

Substrate cleaning

ETL deposition

LiF deposition

Panel unloading

Cutting

Glove Box Vacuum

HTL EML

ETL

9

OLED Equipments

Pretreatment

Chamber

Sputter

Chamber

Electrode

Chamber

Organic

Chamber

Glove Box

Unloading

Chamber

Loading

Chamber UV

Encapsulation

Organic

Chamber

10

Gen2 OLED 장비

11

OLED 장비 및 박막공정 특징

12

Evaporation/ Mask Align System (Small Glass)

13

Point Evaporation Source

(Sublimation; solid vapor)

영구자석 영구자석

Glass Glass

Mask Mask

Mask Holder Mask Holder

Glass Holder Glass Holder

XXY Alignment XXY Alignment

CCD Camera CCD Camera

Shield Shield

Glass Glass Mask Mask

저분자 RGB Patterning

Fine Metal Shadow Mask(Gen. 2 기준)

Hole position variation

: < ±10.0㎛

Mask / Substrate Alignment

: < ± 5.0㎛

Thermal expansion, 기판 처짐 등

⇒ Total Alignment Accuracy

: < ±15.0㎛

14

FMM RGB Patterning

15

Evaporation & Shadow Mask

Shadow

mask 16

Cathode spacer

R.G.B Evaporation White + C/F PLED

Schematic

Merit High Efficiency

Easy Color Control Simple Process Fine Patterning

Large Area Process

Issue Fine Patterning

Large Size

White balance Light Efficiency Loss

Material Performance

RGB Emission white Emission RGB Emission

Color Patterning Issue

R.G.B Evaporation R.G.B Fine Metal Shadow mask Large Size Shadow mask

White + CF Open Mask Evaporation Efficiency of White OLED

PLED Ink-jet Printing Material Performance

Printing Process

Issue : OLED Process

고정세가 상대적어려움 광량이 1/3 Uniformity문제

17

Patterning Process

for

OLED-TV

18

Large area EL Patterning Method (active)

19

<32” Vertical Linear Source FMM

EL Patterning Approaches for Large OLED-TV

Linear source

Vertical FMM

RGB Patterning RGB Patterning

white EL

White EL + CF

55”

55”

SMS (Small Mask Scanning)

Glass moving

21

Linear Evaporation Source for Large Glass

(Data from SUNIC)

RGB EL

22

White EL

Oxide TFT

CF

LTPS

Divided Technologies for OLED-TV

Gen 8 Gen 6

23

White EL Evaporation + Color Filter

White EL CF

EL Patterning Process Comparison

55”

55”

1250

730

Evaporation by SMS (Small Mask Scanning)

Glass moving

(+)

White OLED

24

25

55-inch FHD OLED TV employing New Tandem WOLEDs

By serial stacking of EL layers,

try to improve life time

Other Patterning Methods

26

LITI - SDI

Laser Induced Thermal Imaging

■ 방 식

1. Donor Film

- PET 등의 Substrate에 OLED 증착/Coating

2. Donor와 Receptor Contact at ATM

3. Thermal Imaging-print by Laser

■ 장점

1. 사용 가능한 물질多 (SM-OLED, PLED)

2. Multi-layer stack ability

3. Thermal Imaging-print by Laser

■ 단점

1. Lifetime degradation by lamination

(emission interfaces not good)

2. Particle contamination by contact-type

3. Different materials to conventional OLED

need to develop for Transfer

27

Print Heads

Bank

Substrate HTL LEP ITO

Ink Jet Printing

31

Encapsulation

35

Multiple Layer

Sputtered Inorganic Barrier Layers and Vacuum-deposited Polymer Layers

Active OLED

Ceramic Layers

Isolation Layers

Glass Substrate

Barix coating

Encapsulation

Metal Can or Glass

흡습제(BaO, CaO 등)

UV 접 착 제

UV Mask UV Light

불활성가스(Ar, N2)

36

Encapsulation for Large Area AMOLED Encapsulation for Large Area AMOLED

Flexible OLED

38

How realistic is the Manufacturing of Flexible AMOLED?

39

Manufacturing of Flexible OLED

Flexible Process SMD Flexible AMOLED

Spin Coating of PI Film 열경화

40

Permeability issues of Plastic Substrate

• Issues on OLED - Humidity Protection Permeation of H2O for plastic : ~10 g/m2day Requirement of H2O permeability in OLED

10-6 g/m2day ---- 10,000,000X gap !

It is claimed that multiple layers of

organic/inorganic barrier

can protect EL from moisture

41

7 Multiple Layer Sputter/CVD/ALD

Sputtered Inorganic Barrier Layers and Vacuum-

deposited Polymer Layers

Active OLED

Ceramic Layers

Isolation Layers

Glass Substrate

Barrier coating

Requirement of Thin Film Encapsulation

Issues: Reliability of moisture protection,

Cost of vacuum process, low throughput, Particles

A critical path to Flexible OLED’s Success

Glass Encapsulation