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Large-Area, Integrated, Distributed Electronics

Dr. Robert ReussDARPA/MTO



Macroelectronics


Macroelectronics: Definitions

• Macroelectronics: – Device/circuit technology not driven by need

for smallest possible dimensions, but rather cost and/or form factor (Nominal features in 1-10 um regime)

• Distributed Electronics:– Electronics (ideally macro) spread over

area/volume to conserve space/weight or achieve enhanced functionality

• Conformable/Flexible Electronics:– Electronics fabricated on substrate that allows

shaping to surface or increased ruggedness against mechanical damage (foldable/rollable)


Macroelectronics Opportunity Overview

Low $/cm2 High

Perf

orm

ance

(log

Ft)

Multiple Form FactorsHigh Low

Si ICsTraditional Electronics

& DoD Thrust

Performance Driven

CompoundSemiconductor

αTFTs on Glass

DisplayIndustry

(Cost Driven) TFTs on Plastic

• Fabrication method via cost effective large area processing on flexible substrates; 10-100MHz ckts (early CMOS)

Large AreaPerf TFTs on Flexible

Substrate

RequirementsDARPA

• Electronic material comparable to single crystal Si with potential >100 MHz ckt performance and moderate RF

NWTFT Technology

Nanotechnology-basedNew DoD Capabilities


TFT Capability (µ, cm2/Vs)

Syst

em A

ppl ic

atio

ns (

F t )

• AMLCD• PVs• a-Si, OFETs

• System on Panel• X-ray Imagers• Low performance poly-Si on glass

• RF ID tags, Smart cards• Low performance TFTs on flex

• EM Field Sensors • Adaptable Surfaces• Low Performance RF • High performance TFTs on flex

•Chem-bio sensors •Distributed sensors, communications, beam-steering

& distributed low frequency RF• High performance NWTFT on flex

Large Area, Multifunctional, Distributed Macroelectronics

1 GHz

100 MHz

1 MHz

100 KHz

Program Goals• High µ TFTs on flexible substrate• NWTFT with µ ≥ crystalline• Capability comparable to 2 µm CMOS• Provide solutions to DoD relevant problems based on

• Affordability• Reduced weight/volume• Flexible form factor• Distributed electronics

1

10 100

1000


Active Devices STILL NEEDED!

Transistors and ICs Needed for Smart Large Area Distributed Electronics

Leads To:• Reduced Cost, Weight• Increased Reliability• New Form Factors • Increased Sensor (Sensed) Area

Large Area Distributed Electronics

Direct-write passivecomponents & interconnects

Direct-write batteries

Direct-writehigh gain antenna

Leverage MICE, Metamaterials, Flexible

Displays, etc.


… research, develop, and demonstrate innovative cost-effective, large-area, distributed, flexible electronics to provide improved performance systems to support the warfighter …

• LARGE AREA, e.g. >4ft2, flexible substrate electronics

• High performance flexible TFT – µ > 200 cm2 V-1 s-1; – VT < 1 V– on/off ratio > 107

• Reusable intermediate substrate technology

• Elastic interconnects

• Affordably < $100/sq.ft

DARPA Macroelectronics


Generic Cross Section of Large Area, Integrated, Distributed Electronics

Note: Row/column configuration not required

SensorActuator Array (RF, light, mechanical)

TFT Active Electronics Layer

Energy Storage Layer

Recharge Layer

APPLICATIONS:adaptive surfaces

sensor arraysdisplays

distributed diagnostics


Potential Applications


Potential Applications

Integrated and embedded electronics

Portable beam steering antenna arrays

Health Monitoring System

Driver – reduced weight

Driver – increased functionality/ utility

• Fully distributed strain, pressure & temperature sensing

• Distributed actuation and intelligent control

• Structurally integrated energy storage/generation

• Structurally embedded power and data distribution elements

• Structural Antennas

Driver – increased information


Urban Warfare CommunicationsThe urban arena generates serious communications problems due to multipath. Multiple antennas and transmitters can minimize these effects.

Flexible electronics multi-transmitter/antenna array hung on wall to provide infrastructure for unit communications.

Flexible electronics also provides spatial diversity for the individual soldier with radio embedded into the uniform.

With smart antennas, communications to forward units can also be improved by reducing multipath losses and using active beamforming

to increase gain toward higher headquarters while nulling out jammers and lowering signal

levels toward the enemy.

Flexible electronics “smart” antenna-transceiver deployed as needed

Electronic Scanned Array and transmitters

Processor and display electronics

Foldable “pup tent” radar for alerting and cueing, mortar locating

Large aperture is a must!!

Thru the Wall Imaging

Improved Forward

Unit Comms


Embedded RF Front-end Electronics and Power Harvesting in Flexible Substrates

• Phased arrays on tarps, tents, and easily deployable nets• Embedded solar cells on fabrics and tarp


Light-weight inflatable/wearable large antenna aperture for terrestrial/satellite communications and radar

applications. Desired range of frequency microwave to MMW (1-40GHz)

Metalizedfabric

Embedded RF front-end

Embedded RF Electronics in Flexible Substrates


Technology Needs for Large Arrays

2- Antenna Aperture

3- Advanced Radar Electronics

4- Integration of Electronics with

Radiating Aperture

1- Lightweight Deployable Structures

5- System Integration



Adaptive systems to operate at the “Natural Limit”

• Health monitoring and damage detection

• In-flight reconfiguration, load & drag control

• Exploitation of nonlinear characteristics

• Performance not limited by analytical models

• Reduced factors of safety

• Fully distributed strain, pressure & temperature sensing

• Distributed actuation and intelligent control

• Structurally integrated energy storage/generation

• Structurally embedded power and data distribution elements

• Structural Antennas

Multifunctional Structure Vision

Unmanned systems operating at “natures limits”, continuously sensing the environment, measuring performance and adapting to optimize performance

a-Si:H onpolyimide

Thin Film Sensors


Embedded large area sensor arrays w/integrated signal processing electronics

• Structural integrity of critical components in aircraft or other equipment.

• Rivets/Seams• Cracks in Fuselage• Monitor aircraft integrity while in flight

• Cargo monitoring.• Rapid screening.• Digital image processing to automatically identify suspected cargo.

• Phased array acoustic sensors.• MEMS sensors w/ TFT integrated circuits to separate signal from background.

•Rugged, lightweight, portable x-ray detectors for battlefield hospitals.

• Enable rapid diagnosis of injuries from specialist at remote location.

Requires high-performance thin-film integrated circuits on flexible substrates


Enhanced Performance and Security

• Acoustic Arrays

• Decoys/signature modification

• Smart sensor carpet

• Drag reduction• Naval vessels• Airplanes

Is Macroelectronics the best means to efficiently and cost effectively realize such capabilities? How?

Microbubbles - National Maritime Research Institute of Japan

NASA


Challenges


TFT-based MacroelectronicsTechnical Challenges

(Steel, Glass Sheet, Plastic)

Gate Oxide-No pinholes-Thin for higher performance

Channel-High Mobility-Low Leakage-Smooth Interface

Isolation Oxide

• Material/Process/Substrate Compatibility- process temperatures for optimized devices- substrate stability and surface roughness- O2 and H2O barrier properties- matching coefficient of thermal expansion

• Cost effective tools for 1 µm patterning• Adhesion on flexible substrates

L 0 for high performanceL ~ 1-10 um for affordability

Gate


1950 1960 1970 1980 1990 2000 2010

0

50

100

150

200

250

$US

Bill

ions

Year

Semiconductor shipments Flat panel display shipments

Display Manufacturing asCost Driver

Cumulative volume10000 100000

100

200

300

2008

2001

Progress ratio = 80 %

Estim

ated

aver

age

selli

ng p

rice

($)

HistoricalProjected

2500 ft roll

18” DiameterFunctional circuitry demonstrated at manufacturing speeds of 300ft/sec on a 6in web platform and 7000sheets/hr on a 24in X 36in sheet-fed platform.

ALL Printed Ring Oscillator

ALL Printed ChemFETs


Example Cost Assessmentfor Macroelectronic Application

Number of Chips/cm2

Chi

p C

ost (

$)

1

10

100

1000

10000

100000

0 5 10 15 20 25 30

Assume 103 cm2 (~ 1 ft 2) area with transistors distributed over surface

Assume 103 cm2 (~ 1 ft 2) area with transistors distributed over surface

Microelectronics solutionwith chips distributed over surface

Microelectronics solutionwith chips distributed over surface

1/cm2

Compare toMacroelectronics ~ $100

at $0.10/cm2

Compare toMacroelectronics ~ $100

at $0.10/cm2

$1/Chip

$.10/Chip

But must compete with 108 transistors:• Microelectronics ~1 cm2, $10• Macroelectronics ~1000 cm2, $100

But must compete with 108 transistors:• Microelectronics ~1 cm2, $10• Macroelectronics ~1000 cm2, $100

1/cm2

>$100 for Chips if> 1/ cm2


High mobility TFT

• Suppose Macroelectronic TFTs could reach transition frequencies of fT ~ 10 GHz.• RF circuits can operate at 1/3 - 1/4 of fT .⇒ Well-designed Macroelectronic RF circuits should be able to operate up to 2-3 GHz.⇒ Digital circuits should be able to operate at several hundred MHz

fT Considerations

printed (µCP) Au electrode SWNT

plastic substrate

gatedielectric

channel length L

Assumptions for fT calculation:• µFE = 400 cm2/V-s• Vgs – VT = 2V• L = 1 µm

22)(

LVV

f TgsFET p

m -=

Material/process lever

Moore’s Law Lever

Questionable Economics for

Large Areas

ffTT = = vvsatsat /(2p/(2pLL22gg))

1970 1980 1990 2000 2010 20200.01

0.1

1

10

0.01

0.1

1

10

.25 µm

3.0 µm2.0 µm

1.5 µm1.0 µm

0.8 µm

.35 µm0.5 µm

.18 µm.13 µm

90 nmGate

Length

50 nm

Mic

ron

Feature Size

80286• 100,000 Transistors• 1.5 micron Technology• Speeds from 6MHz to 20 MHz• Capable of addressing 16 MB

1,000,000,000

100,000,000

10,000,000

100,000

10,000

1,000

1,000,000

1970 1980 1990 2000 2010

80088080

802868086

4004

Itanium® 2 Processor

386TM Processor486TM DX Processor

Pentium® 4 Processor

Pentium® II Processor

Pentium® III Processor

Pentium® Processor

Older, slower technology. But cheap!!


1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

GaN(sapphire) [6]

1/f Noise. Hooge parameter for various semiconductors

[1] D'yakonova et. al., AIP Conference Proceedings, no.285, p. 593-8[2] Hack, M. et al., Amorphous Silicon Technology - 1996. Symposium, p. xvii+909, 747-52[3] Levinshtein et al., Semiconductor Science and Technology, vol.9, no.11, p. 2080-4[4] Levinshtein et. al., Journal of Applied Physics, vol.81, no.4, p. 1758-62 [5] Levinshtein et. al., Applied Physics Letters, vol.73, no.8, p. 1089-91[6] Levinshtein et. al. Applied Physics Letters, vol.72, no.23, p. 3053-5

Si [1]

α:Si [2]

GaAs [1]

SiC(6H) [3]

SiC(4H) [4]

GaN(SiC) HEMT [5]

Pentacene TFT

Noise Figure will be major issue for RF and phase 1 focus


Some Macroelectronics Efforts


Long Term VisionNanomaterials for Macroelectronics

While everyone else looks to nanotechnology to make things smaller, DARPA program proposes a paradigm shift

by using nanomaterials to allow electronics to be bigger

5 µm

Nanowires

Measured (colored lines) Measured (colored lines) and modeled (open and modeled (open circles) for transistors. circles) for transistors. Left side shows forward Left side shows forward configuration, right side configuration, right side shows reverse (source shows reverse (source and drain swapped) and drain swapped) configuration.configuration.

Nanowires can be coated uniformly across a substrate


First Nanowire Devices

Bright and dark field views of multiwire device

-200

-150

-100

-50

0I sd

(µΑ)

-8-6-4-20Vsd (V)

80

60

40

20

0

-I sd (µΑ

)

1050-5Vg (V)

-I sd

(µΑ)

1050-5-10Vg (V)

10-5

10-3

10-1

101

-I sd

(µΑ)

1050-5-10Vg (V)

10-5

10-3

10-1

101

On-current: ~100µA @ 1VsdThreshold Voltage: ~1VOn/Off ratio: >106

Mobility ~100cm2/Vs

Initial nanowire devices show promise of high mobility transistors fabricated with low temperature processes


Alternative Transistor Approach?

Tunneling transistor operates at higher frequency than best semiconductor devices available

1.0

10.0

1.0 10.0Gate length (µm)

Ft (G

Hz)

vsat = 1x107 cm-3

τex = 10.0 psec

vsat = 1x107 cm-3

τex = 10.0 psec

Polycrystal High Mobility Semiconductor

Si

Transistor fT (GHz) fmax (GHz)MIM Device 1700 3800Si CMOS 150 30Si Bipolar 50 73SiGe HBT 270 260SiGe MODFET 62 116GaAs MESFET 160 133III-V HBT 305 800III-V HEMT 362 740


Circuit & ElectrodePrinting Station(s)

• lithographic, •silkscreen, etc.• top & bottom patterns

Add drive electronics, connectors, & trim(including optional front glass)

Finished Component

FlexibleSubstrate

Top Laminate• protection• dielectrics (as needed)• top electrodes (as needed)

Dimple Embossing Tool

Panel Dicing Station Corner removal

Wrap web-based panel aroundstructural member

Finish circuitry on back of panel

. . .

Roll-to-Roll Manufacturing Process Needed?


System Design Issues• Impact of Substrate

– Inductor Loss– Capacitive Coupling Loss– Metal Plating/Dielectric Options to

Reduce Losses

• Ft vs Operational Bandwidth– Gain per Stage– Noise Figure

– Early Measurements Required

TFT Circuit Design Process

LNA RF Switch Power Regulator Inductor

RPI AIM-SPICETFT Models

Lehigh TFTCharacterization

Data

UHF TFT Circuits- Design- Fab

TFT Process &Model

EnhancementDemo DesignsUpdated

TFT Models

Device Design Activities• Low Noise Amplifier

– Frequency Range: 400-500 MHz– Gain: 15dB– Noise Figure: 2-3 dB

• RF Switch for Delay Lines– Frequency Range: 400-500 MHz– Loss: 2dB

• Delay Lines (on Flexible Substrate)– Resolution: 4 bits– LSB Length: l/20 (~0.6 inches in er of 4)

• Tasks– Develop Prototype Circuit Designs using

TFT Parameters for Components Required for Radar Demo

– Develop Prototype Antenna Element-Level Designs Incorporating Passives on Flex Substrate

– Iterate Designs with Updated TFT Parameters Derived from Measured Values (Ribbon/Foil TFTs, Direct Fab TFTs)

– Perform Sensitivity Studies to Improve TFT Performance


excellentexcellentexcellent

4~2-42

~30 cm2/s~30-60 cm2/s~ 60 com2/s

Single-crystal SLSDirectional SLS

2-shot SLS

Mostly smooth smooth smooth

200 – 300 cm2/Vs 300-400 cm2/Vs ~ 500 cm2/Vs

SLS for Si Recrystallization

Excellent results demonstrated on glass. Process now being adopted/ optimized for

plastic.

Excellent results demonstrated on glass. Process now being adopted/ optimized for

plastic.

Poly Si TFT BaselineElectropolishing &

Mechanical PolishingAs-received SS-304Mechanical polishing

Ra > 700A Ra > 500 Ra < 50 with low impurities

Alternative Substrates

• The large area polishing of thin metals by combination of manual/chemical polishing and electro-polishing was investigated for

– Type 304 stainless steel– Kovar® stainless steel

Property PIBO Kapton

Dk 2.9-3.1 3.4

Df 0.004 0.001

Heat Shrinkage

0.005% 0.03%

Tg >600C 325C

Tensile Modulus

1400 psi 800 psi

CTE 3-5 ppm/C 18 ppm/C

Substrate materials show promising characteristics for TFT fabrication

and RF applications

Plastic Process Characteristics


Barriers and Issues for Device Design

Device Parameter• Gate dielectric breakdown (especially at

island edges)– Improve deposited SiO2, or find dielectric with

higher integrity– Short-term: use edgeless devices

• Drain leakage current– Limits reverse voltage and off-current– Well-known solution for p-Si: use lightly-doped

drains (LDDs)• Self-aligned vs. non-self-aligned TFTs

– Self-aligned has higher performance– Self-aligned may required substrate to be

exposed to implant activation– Edgeless devices avoid the problem: islands can

be patterned after implant activation• Need high subthreshold slope for switches• More characterization needed:

– Parameter uniformity– Bias-stress instability– Noise figure for macroelectronic receiver front

ends

Test Panel• n-channel and p-channel TFTs• Self-aligned and non-self-aligned

TFTs• Edge and edgeless TFTs• Different width and length TFTs• Contact resistance and directional

sheet resistance test structures• Dielectric integrity test structures• Status: first lot received non-self-

aligned n and p implants, is at Columbia for SLS crystallization and activation


Large-Area Patterning Solutions for Microelectronics, Optoelectronics and MEMS

Stitching Errors Eliminated Using

Seamless Scanning

Lithography

PhotoablationMulti-functional, large-area

imaging system

ANVIK

Key Performance Advantages• Seamless resolution (< 1 µm) and

Large Area (> 1.2 m x 1.5 m) capability• Throughput >6 sq. ft./min; 10,000 vias/sec• System developed for conformal lithography

on non-planar surfaces• System developed for high-speed, maskless

lithography over large-areas• COO 2 – 5X lower than competing technologies

Resolution (µm)1001010.1

100

10

1

0.1

0.01

ContactPrinters

AnvikLarge-AreaProjectionSystems

ICTools

Cost/Resolution Domains

Syst

em C

ost (

$ M

)

large-area, integrated, distributed electronics · page 1 approved for public release, distribution...

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