the flat panel display paradigm: successful implementation ... · 2005 2010 2015 e-paper (portable...

The Flat Panel Display Paradigm: Successful Implementation of Microelectronic Processes on Gigantic Wafers

Dr. Zvi YanivApplied Nanotech, Inc.

3006 Longhorn Blvd., Suite 107Austin, TX 78758

Phone 512-339-5020 x103Fax 512-339-5021

Email [email protected]

Flat Panel Displays (FPD) 2007

FPD

Active Matrix Liquid Crystal (AMLCD)

Plasma (PDP)

Active Matrix Organic Light Emitting Diodes

(AMOLED)

Field Emission (FED)

Samsung PDP

Ken Werner (Nutmeg Consultants)

Sharp AMLCD


LG Philips LTPS AMOLED 20.1”


Predictions…

Once FPDs have achieved comparable size and performance to CRTs, …

FALLING PRICE PREMIUM

CRT

FPD

?

UNIT PRICE

1990 2000 2010

YEAR

American Electronics Association(1990)

Predictions

…, their intrinsic advantages will result in penetration constrained only by their relative price premium versus CRTs

...AND INCREASING SCREEN SIZE...

MAXIMUM SCREEN SIZE

(INCHES)

1990 2000 2010

YEAR

American Electronics Association(1990)

50-

40-

30-

20-

10-

0-

FPD

CRT

Glasses Isotropic Liquids Gases

Mesomorphic Glasses——————

Plastic Crystals

Liquid Crystals(Mesomorphic

Fluids)

Crystalline Solids3-D Long Range

Order

Less Than 3-D Long

Range Order

No Long-Range

OrderORDERING

Definite ShapeAnd Volume

Definite Volume Only

Complete Mobility

MOBILITY

Solids, Liquids and Gases -It’s all About Order

Liquid Crystal?!

Flat Panel Display Technology, Solid State Technology, 1994

Twisted Nematic (TN) Structure

The molecules along the upper plate point in direction ‘a’ and those along the lower pate in direction ‘b’, thus forcing the liquid crystals into an overall twisted state.

Why LC Active Matrix Displays are Necessary?

Need of Time-Multiplexed Matrix Addressing

For passive displays (such as LCDs)

time multiplexing has inherent

limitations

Principals of Operation of a TFT AMLCD

• tp – scanning pulse length

• liquid crystal resistivity ≈ 1012 Ω-cm

• storage time ≈ 20 msec

• polarity of the applied voltage must be inverted periodically:

• reversing the data voltage polarity in each frame

• reversing the data voltage polarity on alternative rows

Energy Band Diagram of Crystalline and Amorphous Silicon

ENER

GY

DENSITY OF STATES

1.1 eV

DENSITY OF STATESEN

ERG

Y

1.75 eV

Plasma Vapor DepositionRF OR DC POWER~ .1 WATT/CM2

HEATER

PLASMAGAS

EXHAUSTGASFEED

PRESSURE ~ 1 TORR

TEMP ~ 250 °C

MATERIAL

α - Si (INTRINSIC)α - Si (p-TYPE)α - Si (n-TYPE)SiO2Si3N4

FEED GAS

SiH4, SiF4, H2(+ B2H6)(+ PH3)SiH4 +N2OSiH4 + NH3

SUBSTRATE

Cross-Section of TFT Pixel Array with Storage Capacitor

Projected Limitations of α-Si TFT AMLCD’s Based on Predicted Technological Improvements

0

2

4

6

8

10

0 5 10 15 20 25 30 35 40

Lithography

Transistor Performance

Gate Delay

Diagonal (in)

Resolution (mm –1)

AMLCD Process Flow

Active Plate

Passive Plate

Cell Display CompletedDisplay

1 2 4

1 3 4

3 4 33

1

2

3

4

Functional In-Process TestOptical Pattern In-Process InspectionPanel InspectionRepair

Pixel Layout Example (α-Si TFT)

Example of Clean Room LayoutYELLOW ROOM

Exp | Coater / Developer






WET ROOM

Wet Etching Stations

Resist Removal Stations

Cleaning Stations

CVD

CVD

CVD

CVD

CVD

Sputtering

Sputtering

Sputtering

Sputtering

Dry Etcher

Dry Etcher

Dry Etcher

Dry Etcher

Cluster Tool Configuration

Transportation Robot

Cassette Station

LD/ULLD/UL

Process Chamber

Process

Chamber Process Chamber

Heating Chamber

Transportation Robot

Block Diagram of TFT-LCD Module

LSI Driver Connection to TCP (tape-carrier package) by ACF

From GEN 1 to GEN 7

Display Size & Pixel Density for Large Screen

Screen Size40”

30”

24”

17”

15”

1M 2M 4M 5M

Pixel Contents

1024x768

1280x1024

1280x768 1920x1200

1280x768

XGA .8M pixelsSXGA 1.5 MUXGA 1.9 MD-TV 1M/2MWUXGA 2.3M

Yield Depend on Screen Size and Pixel Contents

First Generation 7 α-Si

Display Cost

0.26

0.140.18

0.42TFT PlateLightingColor Filter PlateDrive

Comparison of Various Silicon Films

Major Crystallization Methods

Industry Transition to Polysilicon

High

Low

Elec

tric

al P

erfo

rman

ce

(Mob

ility

)

Single Crystal Silicon —— x-Si

Polysilicon* —— p-Si

Microcrystalline Silicon —— m-Si

Amorphous Silicon —— a-Si

Material Applications

Wafers Integrated Circuits(Semiconductors)

Thin

Film

s

Pixe

ls +

Int

egra

ted

Circ

uits

Pixels Only

* Crystallization converts a-Si or m-Si to p-Si

Wide Viewing Technologies

The Old Dream of Hang on the Wall TV is Here Today

Courtesy of Information Display Magazine

What is “Plasma”

Shigeo Mikoshiba, SID Seminars

Where Does the Light Come From?

Shigeo Mikoshiba, SID Seminars

Cross Section of Fundamental Color PDP Structure

Sandblasting Method

Barrier Ribs Made with the Sandblasting Method – Rib Pitch: 130 µm

Negative Features of PDPs

Low luminance (400 cd/m2)

Low contrast ratio (20:1 in bright room)

Low luminous efficiency (1.4 lm/W)

High drive voltage

OLED Displays

OLEDs Need an “Active Matrix”

Shown is a simplified cross-sectional view of a full-color solution-processed OLED device structure.

Ink Jet Processing?

LTPS vs. α-Si as Materials for AMOLED TFTs

Much more sensitiveMuch less sensitiveOLED Degradation

LowHighCurrent Stability

Lower for large panel sizeLower for small panel sizesOverall Cost

HighLowYield

LowHighEquipment Investment

High (External Driver)Low (Built-in Driver)Cost (modile)

LowHighCost (array only)

4 or 5 masks9 or 10 masksNumber of Process Steps

BetterWorseTFT Uniformity

NMOSPMOS and NMOSType of TFT

0.5-150-200Mobility (cm2/V-sec)

α-Si TFTLTPS TFT

The Competing Powers for Large Area FPDs

LCD vs Plasma vs OLEDs

Target for ultra-high definition and wide screen display

F. Sato and M. Seki, IDW ’01, p.1153

Cross-section of FED in operation

Phosphor

Light

Anode Glass

Cathode Glass

Insulating Grid Spacer Layer

Electrons

Grid

Conducting Feedlines

Black Matrix

SCE Display

Schematic cross section of the construction in the SCE display.

PdO fabrication process

Schematic diagram of the PdO fabrication process by using ink jet printing.

SED demo

Glass vs Silicon

Information Display Magazine, 11/05

1995 Lithography Requirements

Minimum Feature Size: 2µm - 5µmLinewidth Control: +10%Layer-to-Layer Overlay: +0.5µm - +1µmThroughput: >10 x 106 mm2 per hourTypical Products: TVs, Computer Terminals, CAD Workstations, Auto Dashboards, Image sensors & Scanners, Print Heads

MRS Technology Inc.

Coating Technology

Spin Coating

Roller Coating

Spray Coating

Slot Coating

Lithography Systems

Contact / Proximity Aligners

Mirror Projection Aligners

Step-and-Repeat Aligners

Schematic of a Scanning Projection Aligner & Schematic of a Stitching Aligner

Flat Panel Display Technology, Solid State Technology, 1994

Stepping Aligners

Available Systems are ‘Adapted’ IC SteppersAdvantages

Multiple SuppliersResolution, Overlay: Sub-Micron AvailableHigh Defect Limited YieldUse Standard IC Masks Available from Multiple SuppliersHigh Throughput for Small Displays

ProblemsLimitations of Projection Optics Constrain Display SizeNo Migration Path to Large Displays

MRS Technology Inc.

The Stitching AlignerThe Job: Make a display of any arbitrary size by stitching together multiple subfields. Analogous to making a brick wall out of individual bricks.Problem #1: Doing it

The ‘mortar joints’ between the ‘bricks’ must be invisible!Many kinds of ‘bricks’ are used!

Problem #2: Doing it Fast!Many exposures, mask changes needed to pattern a single display layerSlow = Expensive = Prototype DisplaysFast = Inexpensive = Production Displays

Problem #3: Doing it EasilyMultiple subfield stitching jobs are complexNeed to know what you get is what you want

MRS Technology Inc.

Cross Pollinations from FPDs to MCMs to Large Si Wafers

Same as aboveSmart weaponsEncryption

Radar

Command & control AvionicsRugged displays

Defense

CPUMemory

DSPASIC’s

Smaller computersHand-held devicesGlobal positioningImage processingArray processors

Computer screensVideo telephones

HDTVAvionics

Information display

Major Applications / Commercial

Manufacturing equipAssembly equipment

Test equipmentMaterials

Manufacturing equipAssembly equipment

Test equipmentMaterials

Manufacturing equipMaterial handlingTest / inspection

Materials

Critical Elements / Technologies

Substrate specsProcess materials



Materials

Mechanical interfaceMaterial handling

Contamination controlCIM





Equipment

Large area processLarge area processLarge area processCritical Segments

400mmMCMFPDAreas of Emphasis

Organic Electronics for Flat-Panel Displays

Passive Matrix and Active Matrix

OLED Displays

Organic Light-Emitting

Diodes

OTFT Active Matrix Displays

on Plastic

Organic Thin-Film Transistors

OTFT LCDs on Plastic

Organic light-emitting (OLEDs) and organic thin-film transistors (OTFTs) are complementary technologies displays. Either technology can stand alone, but they complement one another when used together.

Electronic Ink

An electrical field is applied across a microcapsule to control the motion of contrasting particles and achieve white, black and gray optical states.

Organic AMOLED

Recently, active matrix displays on ultra-thin foil have been fabricated using solution-processed organic TFTs based on a bottom-gate device architecture. The illustration shows cross sections of such a TFT and of a vertical interconnect (via).

Flexible Displays?... What for?

A flexible AMOLED could enable a multipurpose communications device, such as this “pen communicator” concept from UDC.

Flexible Displays

Latest News

A Bridgestone employee displays ‘Quick Response Liquid Display’ (QR-LPD) featuring its nanotechnology already in use for making tires at the company’s laboratory in Tokyo 27 December 2004. The Japanese government plans to set itself national goals in 10 critical technology fields to strengthen the country’s global competitiveness, a report said.

(AFP / File / Yoshikazu Tsuno)

Why Plastic Substrates May Be Needed

Glass is a Wonderful Technology…Unbelievable advances over the last few decadesLarge established infrastructureMassive impact on our daily livesContinuing performance improvements

…butVery capital intensiveVolatile supply & demandComplex packaging / interconnectionsLengthy turnaround / cycle times

Conventional Electronics Manufacturing vs. “Printing”

Plastic Electronics Will Enter a Range of Markets…

PERFORMANCE

TIME

2005 2010 2015

e-paper (portable e-readers, signage)

Basic Logic (disposable electronics

e-film for X-ray sensors

Performance Logic (standard RFID)

LCD TV (light, thin, robust, conformal

OLED TV (light, thin, robust…)

Flexible Backplanes

$2Bn Industry Revenues

$10Bn Industry Revenues

the flat panel display paradigm: successful implementation ... · 2005 2010 2015 e-paper (portable...

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