The Flat Panel Display Paradigm: Successful Implementation of Microelectronic Processes on Gigantic Wafers Dr. Zvi Yaniv Applied Nanotech, Inc. 3006 Longhorn Blvd., Suite 107 Austin, TX 78758 Phone 512-339-5020 x103 Fax 512-339-5021 Email zyaniv@appliednanotech.net
Flat Panel Displays (FPD) 2007 Active Matrix Liquid Crystal (AMLCD) FPD Plasma (PDP) Active Matrix Organic Light Emitting Diodes (AMOLED) Field Emission (FED)
Samsung PDP Ken Werner (Nutmeg Consultants)
Sharp AMLCD Ken Werner (Nutmeg Consultants)
LG Philips LTPS AMOLED 20.1 Ken Werner (Nutmeg Consultants)
Predictions Once FPDs have achieved comparable size and performance to CRTs, FALLING PRICE PREMIUM FPD UNIT PRICE CRT? 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... CRT MAXIMUM SCREEN SIZE (INCHES) FPD 50-40- 30-20- 10-0- 1990 2000 2010 YEAR American Electronics Association (1990)
Solids, Liquids and Gases - It s all About Order O R D E R I N G No Long-Range Order Less Than 3-D Long Range Order 3-D Long Range Order Glasses Isotropic Liquids Gases Mesomorphic Glasses Plastic Crystals Crystalline Solids Liquid Crystals (Mesomorphic Fluids) Definite Shape And Volume Definite Volume Only Complete Mobility MOBILITY
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 t p scanning pulse length liquid crystal resistivity 10 12 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 ENERGY 1.1 ev ENERGY 1.75 ev DENSITY OF STATES DENSITY OF STATES
Plasma Vapor Deposition RF OR DC POWER ~.1 WATT/CM 2 PRESSURE ~ 1 TORR GAS EXHAUST PLASMA GAS FEED SUBSTRATE HEATER TEMP ~ 250 C MATERIAL α - Si (INTRINSIC) α -Si (p-type) α -Si (n-type) SiO 2 Si 3 N 4 FEED GAS SiH 4, SiF 4, H 2 (+ B 2 H 6 ) (+ PH 3 ) SiH 4 +N 2 O SiH 4 + NH 3
Cross-Section of TFT Pixel Array with Storage Capacitor
Projected Limitations of α-si TFT AMLCD s Based on Predicted Technological Improvements 10 8 Resolution (mm 1 ) 6 4 2 Lithography Transistor Performance Gate Delay 0 0 5 10 15 20 25 30 35 40 Diagonal (in)
AMLCD Process Flow 1 2 4 Active Plate 3 4 3 3 1 3 4 Passive Plate Cell Display Completed Display 1 2 3 4 Functional In-Process Test Optical Pattern In-Process Inspection Panel Inspection Repair
Pixel Layout Example (α-si TFT)
Example of Clean Room Layout YELLOW ROOM Exp Coater / Developer Exp Coater / Developer Exp Coater / Developer Exp Coater / Developer Exp Coater / Developer Exp Coater / Developer WET ROOM Wet Etching Stations Resist Removal Stations Cleaning Stations CVD CVD Sputtering Dry Etcher Dry Etcher CVD CVD Sputtering Dry Etcher CVD Sputtering Sputtering Dry Etcher
Cluster Tool Configuration Process Chamber Process Chamber Process Chamber Heating Chamber LD/UL LD/UL Transportation Robot Transportation Robot Cassette Station
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 Size 40 1280x768 30 24 1280x768 1920x1200 17 15 1024x768 1280x1024 XGA.8M pixels SXGA 1.5 M UXGA 1.9 M D-TV 1M/2M WUXGA 2.3M 1M 2M Pixel Contents 4M 5M
Yield Depend on Screen Size and Pixel Contents
First Generation 7 α-si
Display Cost 0.42 0.18 0.26 0.14 TFT Plate Lighting Color Filter Plate Drive
Comparison of Various Silicon Films
Major Crystallization Methods
Industry Transition to Polysilicon High Electrical Performance (Mobility) Material Single Crystal Silicon x-si Wafers Polysilicon* p-si Microcrystalline Silicon m-si Thin Films Applications Integrated Circuits (Semiconductors) Pixels + Integrated Circuits Low Amorphous Silicon a-si 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
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/m 2 ) 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 solutionprocessed OLED device structure.
Ink Jet Processing?
LTPS vs. α-si as Materials for AMOLED TFTs LTPS TFT α-si TFT Mobility (cm 2 /V-sec) Type of TFT TFT Uniformity Number of Process Steps Cost (array only) Cost (modile) Equipment Investment Yield Overall Cost Current Stability OLED Degradation 50-200 PMOS and NMOS Worse 9 or 10 masks High Low (Built-in Driver) High Low Lower for small panel sizes High Much less sensitive 0.5-1 NMOS Better 4 or 5 masks Low High (External Driver) Low High Lower for large panel size Low Much more sensitive
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 Light Anode Glass Phosphor Black Matrix Electrons Grid Conducting Feedlines Insulating Grid Spacer Layer Cathode Glass
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 - 5µm Linewidth Control: +10% Layer-to-Layer Overlay: +0.5µm - +1µm Throughput: >10 x 10 6 mm 2 per hour Typical 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 Steppers Advantages Multiple Suppliers Resolution, Overlay: Sub-Micron Available High Defect Limited Yield Use Standard IC Masks Available from Multiple Suppliers High Throughput for Small Displays Problems Limitations of Projection Optics Constrain Display Size No Migration Path to Large Displays MRS Technology Inc.
The Stitching Aligner The 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 layer Slow = Expensive = Prototype Displays Fast = Inexpensive = Production Displays Problem #3: Doing it Easily Multiple subfield stitching jobs are complex Need to know what you get is what you want MRS Technology Inc.
Cross Pollinations from FPDs to MCMs to Large Si Wafers Areas of Emphasis FPD MCM 400mm Critical Segments Large area process Large area process Large area process Equipment Mechanical interface Material handling Contamination control CIM Mechanical interface Material handling Contamination control CIM Mechanical interface Material handling Contamination control CIM Materials Substrate specs Process materials Substrate specs Process materials Substrate specs Process materials Critical Elements / Technologies Manufacturing equip Material handling Test / inspection Materials Manufacturing equip Assembly equipment Test equipment Materials Manufacturing equip Assembly equipment Test equipment Materials Major Applications / Commercial Computer screens Video telephones HDTV Avionics Information display Smaller computers Hand-held devices Global positioning Image processing Array processors CPU Memory DSP ASIC s Defense Command & control Avionics Rugged displays Smart weapons Encryption Radar Same as above
Organic Electronics for Flat-Panel Displays Passive Matrix and Active Matrix OLED Displays OTFT Active Matrix Displays on Plastic Organic Light-Emitting Diodes 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 solutionprocessed 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 decades Large established infrastructure Massive impact on our daily lives Continuing performance improvements but Very capital intensive Volatile supply & demand Complex packaging / interconnections Lengthy turnaround / cycle times
Conventional Electronics Manufacturing vs. Printing
Plastic Electronics Will Enter a Range of Markets $2Bn Industry Revenues $10Bn Industry Revenues P E R F O R M A N C E Flexible Backplanes OLED TV (light, thin, robust ) LCD TV (light, thin, robust, conformal Performance Logic (standard RFID) e-film for X-ray sensors Basic Logic (disposable electronics e-paper (portable e-readers, signage) TIME 2005 2010 2015