EPL Critical Review - SEMATECH · NGL Workshop, Pasadena, CA EPL Critical Review 08/29/01 1 EPL Critical Review Nikon/IBM/Selete Outline: 1. Introduction 2. Program Overview 3. Technology

　NGL Workshop, Pasadena, CA EPL Critical Review 08/29/01 1

EPL Critical Review

Nikon/IBM/Selete

Outline: 1. Introduction 2. Program Overview3. Technology Development4. Summary


1) Overview of EPL programsincluding target devices and schedule(especially for Selete/Nikon)

2) Report of latest status of technologydevelopment

Purpose of EPL Critical Review


Status since 4th NGL Workshop - 1

1) e-Lith program cancelled in Dec. 2000.U.S. device manufacturers, mask suppliers, etc. interested in EPL have been groping for the new EPL organization.

2) Selete officially decided to support EPL.　　Selete will identify and resolve critical issues

in EPL, in cooperation with suppliers and 　　 overseas EPL interested groups.

Nikon expects Selete to function like “a coreof EPL virtual consortium”.


Status since 4th NGL Workshop - 2

3) IBM EO column delivered to NikonThe electron optical column for EB Stepper hasbeen installed at Nikon’s Kumagaya Factory.

4) Active Infrastructures (presented on 8/30) Mask Blanks/Patterning: HOYA, DNP, TOPPAN,

MCOC/PhotronicsPost Processing Software: Seiko InstrumentsMask Repair: Seiko InstrumentsResist: TOK


*Critical issues to be addressed- Mask infrastructure

- standardization- availability

- Resolution & throughput enhancement and trade-off between them

- Stitching data- Wafer heating data- Vacuum stage

Review of 4th NGL Workshop


Agenda - Overview of EPL Program

- Introduction K. Suzuki (Nikon)

- Nikon Program Update Yamaguchi (Nikon)

- EPL’s Place in IBM’s Lithography RoadmapGomba (IBM)

- Selete EPL Program Yamabe (Selete)


Agenda -Technology Development- PREVAIL - Development Status of Electron Optics

Pfeiffer (IBM) - Design and Development Status of EB Stepper

Miura (Nikon)- EPL Mask & Data Post Processing Software

Kawata (Nikon)- Experimental Data of Resist Exposure/Aerial Image

K. Suzuki (Nikon) - Future Electron Optics Sogard (Nikon)

- Summary K. Suzuki (Nikon)

Nikon NSRNikon2001 Next Generation Lithography Workshop Aug.29, 2001 1

Nikon Corporation

Nikon Electron Beam Projection Lithography Program

Takeshi Yamaguchi

2001 Next Generation Lithography Workshop


Outline

1. Nikon’s NGL strategy and EPL

2. Mix and match of EPL

3. Development program and framework of EPL

4. Conclusion


95 97 99 02 05 08 11

Min

imum

Fea

ture

Siz

e (n

m)

(DR

AM

Hal

f-Pitc

h)

500

350

250

180

130

100

70

50

35

2595 97 99 02 05 08 11

1994 SIA

1997 SIA

1998 / 1999 ITRS

ITRS DRAM 1/2 Pitch2000 Update Proposal

ITRS 2000 Update Roadmap Acceleration

SEMATECH 2001 Plan(2 year cycle to 70nm)

1-1


1-2 Nikon’s NGL Strategy

No perfect solution in terms of: • Resolution• Multi-node extendibility• Throughput• Tool delivery timing• Mask infrastructure timing• Resist timingUncharted territoryMultiple Solutions (F2, EPL, EUVL) with amix&match strategy for different device types.

F2, EPL, EUVL


• ArF (193 nm) lithography will be extended to the 100 nm node and beyond using ultra-high NA and resolution enhancement technologies.　　　　

• F2 (157 nm) lithography is expected to play a major role because of its potential high throughput. But some issues, such as large birefringence, are delaying the development.

• Nikon thinks EUV lithography can be implemented, but a number of issues remain to be settled prior to development of a production worthy tool.

• EPL is attractive as a realistic tool to be in time for the 70 nm node. Nikon’s alpha tool will be completed in late 2002, and the production model will be demonstrated in 2004.

1-3 Overview of Each Lithography


CYITRS2000 DRAM(1/2pitch)SC.2.0 MPU(gate in resist)

1-4 Nikon Lithography Roadmap (for critical layers)

EUV

F2157 nm

99 00 01 02 03 04 05 06 07 08 09 10 11 12 13

180 130 90 65 45 33140 90 60 45 32 23

KrF

EPL

248 nm

ArF will be pushed below 90nm or more.

F2 will be delayed and will have a short lifetime for critical layers.

EUV timing is questionable.

EPL will be in time despite low throughput.

ArF193 nm


1-5 Why does Nikon proceed EPL ?

• Realistic technology• EPL is extendible down to 35nm node• Nikon’s EB technology dated back to 1983• Good synergetic alliance with IBM• World wide industrial support

• Large benefit will be provided to the customers


1-6 Critical issues and development status

• The alpha column is proven as its basic performance; -70nm resolution, 5mm deflection, Subfield stitching control-

• Subfield stitching; - Subfield distortion and placement are proven to be well controlled to stitch the subfield to subfield within around 5nm.

• The vacuum stage; - vacuum compatible air guide works well, and whole mechanical subsystem is under construction –

• Commercially available EPL mask is in readiness for tool timing. - 　　　　　　　　　　　　　　　　　　　　　　　　 - 　　　　

• New concept lens modeling will provide significant improvement of the throughput.


2-1 Where EPL should be used ?

• For the 70nm node, EPL will be implemented to the critical levels, such as gate and contact layers of high performance logic. These layers are relatively difficult for ArF or F2, buteasy for EPL.

• Single binary mask cost will reduce the CoO for small volume production devices of an ASIC and SOC.

• For the 50nm node, EPL will expand the role, because F2 could not extend to this node and EUV seems not to be in time for process proven tool.

• New concept electron optics will enhance the throughput over 30 or 40 wafers/hr.


i KrF ArF

F2KrF

KrF EPL/EUVF2

i ArF

ArF

i KrF ArF

KrF

KrF EPL

i ArF

ArF

EPL

Logic device DRAM, MPU

100 nm

70 nm

50 nm

100 nm

70 nm

50 nm

2-2 Schematic View of Tool Sharing - Mix and Match

Rough Middle Critical

Rough Middle Critical

DRAM　　　　node will be delayed

Time


3-1 Nikon EB stepper Development Program CY 99 00 01 02 03 04 05 06 07　　　　

EO (100 nm/70 nm)

Body & Stage

70nm

ProductBody, Stage

EO (70 nm/50 nm)

ModelingDesign

Fabrication

Fabrication Characterization

Total Integration

Fabrication

Fabrication

Total Integration

Exposure Evaluation

Design

Characterization

Modeling

Wafer Exposure

Prototyping

Body, Stage

Fabrication

Total IntegrationFabrication

50nm

Product

70nm

R&D

New Concept Lens


3-2 Projected Tool Evolution of EPLTh

roug

hput

(WPH

30

0 m

m )

Resolution (nm)50 70 10035

40

30

20

10 R&D Tool

35nm Prod EO

CL:Critical layer 20%

DL:Dense layer 50%

New concept lens Higher speed reticle stage

New concept lens Higher speed reticle stage

CL

DL

CL

DL

CL

DL

Enhanced 3D-CVAL

Enhanced 3D-CVAL70 nm Prod

EO

50nm Prod EO

Non-complementary reticleResist : 5uC/cm2Field : 20mmx25mmReticle :200mm diam.

Nikon NSRNikon02/27/01 SPIE Meeting

Nikon

MaskResist

Data Conv.

Process

HOYA , Toppan,DNP, Photronics 　・・・・　・・・・　・・・・　・・・・

SELETE/ US group

World Wide Device manufacturers・・・・・・・・・・・・

Data conversion vendors , SII etc

TOK , Fuji, JSR etc.・・・・・・・・・・・・Tool suppliers …

3-3 EPL Development Framework


4-3 World Wide Industrial Support

SeleteSeleteSeleteSelete US US US US GroupGroupGroupGroup

NECNECNECNECFujitsuFujitsuFujitsuFujitsuMatsushitaMatsushitaMatsushitaMatsushitaHitachiHitachiHitachiHitachiSonySonySonySonyToshibaToshibaToshibaToshibaSamsungSamsungSamsungSamsungMitsubishiMitsubishiMitsubishiMitsubishiSharpSharpSharpSharpOkiOkiOkiOkiSanyoSanyoSanyoSanyoRohmRohmRohmRohm

Int. Int. Int. Int. SematechSematechSematechSematech

IBMIBMIBMIBMAGEREAGEREAGEREAGERETITITITIMotorolaMotorolaMotorolaMotorolaIntelIntelIntelIntelAMDAMDAMDAMDHPHPHPHPTSMCTSMCTSMCTSMCHyundaiHyundaiHyundaiHyundai

InfineonInfineonInfineonInfineonST MicroST MicroST MicroST MicroPhilipsPhilipsPhilipsPhilipsHOYA ,Toppan, DNP

Photronics……KLA .TOK, Ohlin..JSR..SII　　　　etc.

UMC

Micron

NikonNikonNikonNikon

Virtual World Wide Consortia

Each site has soft connection


4 Conclusions

• Current tool and infrastructure status show EPL will be promised technology.

• Nikon will demonstrate its EPL full field alpha tool capability in 2002.

• Volume production tools for early 70nm node will start to ship from 2004.

• EPL will print high resolution patterns with existing single layer resists. The resolution is extendible down to the 35 nm node.

• A new lens concept will enable high throughput to be maintained down to the 35 nm node.

5th NGL Workshop, August 2001, Selete - M. Yamabe 1

Selete EPL ProgramMasaki YAMABE

Advanced Technology Research DepartmentSemiconductor Leading Edge Technologies, Inc.

(Selete)


Outline

Project “Asuka”Selete EPL Program

Resist and ProcessMask InspectionData Handling

Summary


Project “Asuka”Term: April 2001 - March 2006 (5 years)Goal: Development of Infrastructures for SoC with

100 - 70nm Technology NodePrograms: Device/Process Technology: Selete, $580M (5 years)

Design Technology: STARC, $115M (5 years)Device/Process Technology Program (Selete)

Lithography and Mask– VUV Lithography and Mask– EPL (Electron-beam Projection Lithography)

FEP (Front End Process)– A transistor module, including a gate stack employing a new High k material

BEP (Back End Process)– An interconnect module including Cu and a new Low k inter-metallic dielectric

“Asuka” Research Line– Test fabrication line for the development of above items– A line consists of 300mm equipments


Selete EPL Program

TEG Application

Data Handling Software

Mask Inspection(Transmission E-beam)

Mask Repair(Focus Ion Beam)

EPL Resist

EPL Process(PEC: Proximity Effect

Correction)

EPL Exposure Tool(Nikon E-beam Stepper)

20052004200320022001Fiscal Year (Apr-Mar)

Unit and System Evaluation

70nm Resist Fix

Operation

Improvement

Basic Study Refine performance

Feasibility Study

Operation and Improvement

Application in Asuka

Establish PEC

Process Study (Various Substrates) TEG Process Development

Install

50nm Resist Fix

Tool for Stencil Mask Tool for Membrane Mask

System Development

Total System Improved Fracturing and PEC Software Finish

Confirm PEC PrincipleBasic Study

Tool Development

Tool Finish

Evaluation & Development

TEG: Test Element Group


Negative Tone

Resists Results

Exposure Tool: Nikon E-beam Projection Experimental 100kV Column, *: Photo: Courtesy of Nikon

Dense L/S(1:1)Dose: 8.4µC/cm2

Thickness: 300nm

Positive Tone

Sparse L/S(1:4)Dose: 15.5µC/cm2

Thickness: 200nm

Dense L/S(1:1)Dose: 5.0µC/cm2

Thickness: 250nm

HoleDose: 12.5µC/cm2

Thickness: 500nm

60nm* 60nm*

35nm* 80nm


Resist Status

Sensitivity [100kV] (µC/cm2)

Reso

lutio

n[1:

1 L/S

] (nm

)

0

40

120

20

6080

100

0 5 1510

Target

Etching Rate (Relative)0 0.2 0.4 0.6 0.8 1.0 1.2

i-line ResistNega-1Posi-1Posi-2Posi-3Posi-4

Selete is Developing in Cooperation w/ Resist Suppliers etc.Sensitivity and Resolution: Approaching the TargetEtching Durability: ExcellentPattern Collapse: Need Control

New Process DevelopmentLine Edge Roughness: Need Evaluation and Improvement

PosiNega


80nm Logic Gate PatternGate 80nm (Pitch 190nm)

Exposure Tool: Nikon E-beam ProjectionExperimental 100kV Column

Mask: Made by Nikon and SeleteResist: Negative Tone, 300nm thick


Requirements for EPL Stencil Mask InspectionInspection of Deep Trench or Hole (Pattern:200nm, Si:2µm Aspect Ratio:10)High Resolution (Better than 50nm)High Speed (A Few Hour/Mask)

Results from Feasibility StudyReflection and Transmission SEM Image of Stencil Mask (HOLON EST-100)

Reflection Transmission

EPL Mask Inspection

Reflection Transmission

Selete’s PlanDevelop Transmission E-beam Inspection TechnologyTEM Type + High Speed Image Acquisition Method


Data Handling in EPLSub Field Fracturing

Complementary Fracturing

Proximity Effect Correction

&

Selete’s PlanDevelopment of Each Sub System (Fracturing, PEC) Evaluation and Improvement of the Data Handling Software

Developments of Software are Now Under Way by Software Vendors(SII, NCS, ISS etc.)


Mask A + BPattern Split by “M-Split”

Identification of Singular PatternsStress Check to Judge Split NeedMinute Feature CheckComplementary SplitPattern Area Density BalancingResizingEdge Shape CorrectionVerification


SummaryProject “Asuka” has started to developthe infrastructure for 100 – 70nm node SoC

Electron-beam Projection Lithography (EPL) is one of key programs of “Asuka”, operated by Selete

Selete is developing EPL technology focusing on critical issues

PREVAILDevelopment Status of Electron Optics

Projection Reduction Exposure with Variable Axis Immersion Lenses

Hans C. PfeifferIBM Microelectronics, East Fishkill, NY

NGL Workshop EPL Critical Review

Pasadena, CA, August 29, 2001

H. C. Pfeiffer PREVAIL - Development Status of Electron Optics 08/29/2001 Pg 1

OutlinePREVAIL Electron Optics System3D CVAL Imaging ConceptElectron Optics System OperationEarly Results:

Feature Resolution3D CVAL DeflectionDistortion ControlSubfield Stitching

Summary


Alpha E/O System at Nikon in Kumagaya, Japan


CVAL Subfield Imaging

Contrast Aperture

Wafer Plane

Reticle

2.375mm

12.35mm

1.3mm

1.3mm

#20#1


Imaging CVAL Setup

A only

A & B

Lens only

B only

Reticle

Wafer

Doublet Lens Group B

Group A


Graphic User Interface: Subfield Image Display


Stencil Reticle Examples

400 nm slots in 1.5 µm Sifor printing 100 nm linesand spaces on the wafer


1x1 mm2 Subfield Reticle (Zoom)


x:/.../Image13.TIF

70nm Pattern Features in Resist


PREVAIL Images - Deflected ± 2.375mm5mm


Subfield StitchingRequires Control of Subfield Shape & Placement

MagnificationRotationOrthogonalityTranslation

Three focus coils & two stigmators independently control:Subfield MagnificationSubfield RotationSubfield OrthogonalityFeature Resolution / Astigmatism


Subfield Stitch Pattern

Subfield 9 Subfield 11Subfield 10

Metrology MarkStitch Vernier



Subfield Stitch - Vernier SEMs



Subfield Stitch - Vernier Micrographs

9

10

11

10


Subfield Stitch - Measurement ResultsSubfield 9 Subfield 10

1

2

3

4

1 2 43Position at SF Boundary

Bar S

paci

ng -

nom

(nm

)102030

0

Vertical Stitching data1σσ = 14.8nm

-10-20-30

1 2 43Position at SF Boundary

Bar S

paci

ng -

nom

(nm

)

0

5

10

15

20

25

Horizontal Stitching data1σσ = 1.9nm


SummaryThe PREVAIL electron optics subsystem developed at IBM has been installed at Nikon's facility in Kumagaya, Japan, where it will be integrated into the Nikon commercial EPL stepper tool by YE 2001Cornerstone of the electron optics design is the Curvilinear Variable Axis Lens (CVAL) technique originally demonstrated with a Proof of Concept (POC) systemEarly results obtained with the new PREVAIL electron optics subsystem have demonstrated sub-100nm resolution, sub-10nm distortion and encouraging subfield stitching


NGL010829HANDOUT 1

Nikon Nikon NSR

Nikon Electron Beam Projection

Lithography System:

Design and Development Status of EB Stepper

Takaharu Miura

Nikon Corporation

NGL010829HANDOUT 2

Nikon Nikon NSR

Presentation OutlineFundamental System Concept

Total Development Strategy

Vacuum Air Guide Stage Development Status

Main Body and Control System Development Status

Overall Summary

NGL010829HANDOUT 3

Nikon Nikon NSR

EPL System Exposure Concept

DeflectorStage ContinuousMovement

Reticle Stage

Reticle

Beam Deflection

Sub-field: 1mm

Sub-fields

Deflector

Beam Deflection Wafer Stage

Sub-field: 0.25mm

Wafer

Stage ContinuousMovement

Projection Lens 1/4 Mag.

Scan

Scan

Step

NGL010829HANDOUT 4

Nikon Nikon NSR

ReticleLoadStation

Load LockVacuum

ReticleLoader

VacuumSystem

WaferHandler

Cassette

WaferLoader

ReticleStage

WaferStage

Reticle VacuumChamber

IlluminationColumn

Wafer VacuumChamber

Reticle

Inte

rfer

omet

erO

ptic

sIn

terf

erom

eter

Opt

ics

WaferBackscattered Electron Detector

Load Lock Vacuum

LoadLock

ProjectionLens

Mirror

Mirror

AF/AL

AF/ALAF/AL

AF/ALAlignment / Observation Scopes

LoadLock

EnvironmentalChamber

Prealigner

EPL Mechanical System Block Diagram

3-Point AVIS System

Laser I/F

Laser I/F

NGL010829HANDOUT 5

Nikon Nikon NSR

Technology

Combination

-EB-Vacuum

S205, S305

- High Stiffness

- Vibration-free Concept- Reaction Force Cancel

- Enhanced Vibration-free- Momentum Conserv. Design

- Modular StructureMake most use of Nikon’s expertise!

‘01

‘99

‘98S204

S203

Platform Family

- For 300mm Wafer

‘96~97

S201, S202

‘98~‘99

S202/300, S302

Optical Lithography Tool

EB60～～～～

CD180

‘83～～～～

~‘96

EB1 ProtoR&D Tool

EB2 Production

Tool

‘03 ’04～～～～

1st VacuumBody & StageMagnetic Field

management

HigherThroughput

Small Footprint

ＥｌｅｃｔｒｏｎＥｌｅｃｔｒｏｎＥｌｅｃｔｒｏｎＥｌｅｃｔｒｏｎＢｅａｍＢｅａｍＢｅａｍＢｅａｍ

ＬｉｔｈｏｇｒａｐｈｙＬｉｔｈｏｇｒａｐｈｙＬｉｔｈｏｇｒａｐｈｙＬｉｔｈｏｇｒａｐｈｙTool

Body Platform Development Strategy

NGL010829HANDOUT 6

Nikon Nikon NSR

Vacuum Wafer/Reticle Handler

Magnetic Shield

ManagementNew Control

Function・・・・Filter/Predictor

Vacuum & Magnetic Shield

・・・・Air Guide・・・・Linear Motor

Wafer HeCooling

New Development & New Design Areas

System Control

Stage

Heat Management

Reaction ForceCanceller Vacuum

・・・・System Control・・・・OutgasMain Body

Common Technologyestablished byOptical Scanner

Common Engineeringestablished byEB60, CD180

EPLNew Development Item

NGL010829HANDOUT 7

Nikon Nikon NSR

見える誤差

見える誤差

見える誤差

見える誤差

General Design Strategy for Writing Accuracy

WS Motion Control Error

by I.F.RS Motion

Control Error by I.F.

Filter/Predictor Correction

Performance

E-Beam Shift due to E/O Column mechanical deformation and

Magnetic Field Variation

Body Metrology Frame Deformation due to stress and

thermal variation

Observable

Un-observable

Total Motion Control Analysis

E/O & Mask Error

Structual & Magnetic Model Analysis

E/O Writing Accuracy Estimation

NGL010829HANDOUT 8

Nikon Nikon NSR

Basic Development Strategy Summary

Make most use of the following Nikon’s expertise.

Optical Scanner Synchronization Control Technology

CAE Technology for Vacuum Body/Stage Design Optimization

Optical Scanner Air-guide Stage TechnologyOptical Scanner Software LibraryEB Instrument Technology with NTTVacuum Instrument Technology with NTT

NGL010829HANDOUT 9

Nikon Nikon NSR

Nikon’s EPL Stage Key Design Concept

Vacuum Compatible Air Bearing GuidesLow ParticulatesLow HysterisisLow Maintenance

Linear MotorsHigh Performance (Speed, acceleration, bandwidth)High Magnetic Shielding to minimize electron optics disturbances

Piezo-driven Leveling TableHigh controllability and no magnetic field

Reaction Force CancelingReaction forces from the stages are are passed to an

external frame structure to reduce body disturbance.

NGL010829HANDOUT 10

Nikon Nikon NSR

1-Axis Vacuum Airguide Testset

Low vacuum pipe

Airpad Air supply pipe

High vacuum pipe

Assembly & Sealing Procedure Determination

Special Ceramics Surface Coating

Gas leak & Outgas Measurement

NGL010829HANDOUT 11

Nikon Nikon NSR

Production Air Stage for Optical Scanner

Movable Mirror

Linear MotorAir Guide (X)

Linear MotorAir Guide (X)

Linear MotorAir Guide (Y)

Granite Base

Wafer Holder

Laser Interferometer

(X)

NGL010829HANDOUT 12

Nikon Nikon NSR

-30

-20

-10

0

10

Amplitude [dB]

12 3 4 5 6 7 8 9

102 3 4 5 6 7 8 9

1002 3 4 5

Frequency [Hz]

Reticle Stage Velocity Servo Frequency Response CurveY Scan Axis

Enough Performance. OK

NGL010829HANDOUT 13

Nikon Nikon NSR

Reticle Stage Motion Control Simulation　　　　Simulation Condition & Requirement for E/O correction;

Scan velocity　　　　0.4[m/s]

Average　　　　acceleration　　　　2[m/s2]

Allowable Synchronization error

< 5[um]Calculated Error <1μμμμ

OK

NGL010829HANDOUT 14

Nikon Nikon NSR

Vacuum Air guide Stage SummaryEPL Vacuum Airguide Stages have been developed and

prototyped in order to verify their performances. According to the results, we are confident that these stages meet the required performances for the EPL system in terms of motion controllability, outgassing, magnetic shielding.

Stages use vacuum-compatible air bearings and are driven by shielded linear motors.

Table leveling on stage is driven by piezo actuators.

Total simulation models of the stage and control system have been developed and experimental data taken on the prototype stages show good collation with simulation results.

NGL010829HANDOUT 16

Nikon Nikon NSR

In collaboration with IBM, Nikon has accomplished a In collaboration with IBM, Nikon has accomplished a tremendous amount of design and engineering effort in the past tremendous amount of design and engineering effort in the past years and now years and now entering the product fabrication phaseentering the product fabrication phase. Software . Software development is now going on schedule.development is now going on schedule.

Thermal analysisThermal analysis has been done to improve the design of the stages, has been done to improve the design of the stages, actuators, and electron optics components. actuators, and electron optics components. Thermal DataThermal Data were taken on were taken on prototype Linear Motors and Stages.prototype Linear Motors and Stages.

Experimental tests, theoretical analysis, and FEM Experimental tests, theoretical analysis, and FEM modelings modelings for magnetic for magnetic shield were carried out to optimize the shield were carried out to optimize the magnetic shieldingmagnetic shielding of the system and of the system and the the air bearingair bearing design.design.

This effort together with IBMThis effort together with IBM’’s electron optics expertise and s electron optics expertise and NikonNikon’’s EB related system and precision body/stage expertise s EB related system and precision body/stage expertise will will ensure the achievement of high performance EPL system.ensure the achievement of high performance EPL system.

Overall Summary

2001 NGL Workshop EPL Critical Review Pasadena,CA1

1 　　　　 08/29/2001 S.KNikon NSRNikon

EPL Reticle and Pattern Data Post-Processing Development

Nikon Corporation

Outline: 1. Introduction 　　　　　 2. Reticle Development

3. Infrastructure Development 4. Pattern Data Processing5. Summary



200mm EPL Stencil Reticle

Si membrane (2μμμμm)

Minor Strut

Membrane area Major Strut

Stencil Pattern



200mm EPL Reticle Format

displacementmeasurement marks

1.3

1.3

54.43

132.57

Si substrate(φ200)

Major strut

0.17

MinorStrut

Si membrane

2μμμμm

725 μμμμm

Minor StrutElectron Beam

170 μμμμm

1.13mmSkirt1mm

Pattern Area (1x1mm2)



　　　　EB Reticle Fabrication Process Flow



　　　　Blank Fabrication using SOI Wafer

Advantage:

-Easy control of Si Membrane Thickness

-Vertical Strut Fabrication by Dry Etching

Disadvantage:

- Compressive Stress due to SiO2　　　　

　　　　　　　　　　　　　　　　Compressive Stress Membrane

Silicon Membrane

SOI Wafer

Silicon SubstrateSiO2　　　　Layer

(Etch Stop)

Membrane Etching

+

Removal of Oxide Layer

Membrane Stress has to be Adjusted.



　　　　EPL Reticle Development at Mask Manufactures

-Mask Manufactures have started to develop EPL

Reticle.(DNP,Toppan,HOYA,Photronics).

-100mm fabrication processes are almost completed.

(Commercially available)

-They are in 200mm development phase.

-200mm reticle (sample) will be delivered in 2002.



100mm Reticle Development

Nikon75mm reticle for experiment & technology develop.

Expected Reticle Type Deliver Schedule

CY 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13

200mmReticle

Development200mm Production Reticle

Stencil Type(Standard Type)

Continuous Membrane Type

EB Reticle Delivery Schedule

EPL first tool

Mask Manufactures

DNP,Toppan,HOYA,Photronics



Reticle Fabrication Issues/Infrastructures

Items(Developers)

Pattern Design

Pattern Split

Fabrication Process

Pattern Inspection

Pattern Repair

Reticle Cleaning

Design Platform （（（（Seiko Instruments/SII,Nikon））））Proximity Correction（（（（Selete,SII））））

Data Split (Selete,ISS,SII)　　　　/ Commercially available

Reticle Blank Fabrication, Reticle Fabrication (Mask Manufactures /DNP,Toppan,HOYA,Photronics)

Optical Rough Search System, EB Inspection System(Selete + αααα)/planning

FIB Repair System (SII) / planning　　　　In process：：：：Megasonic Cleaning

In-situ Cleaning:Ar-aerosol Cleaning (Sumitomo Heavy　　　　Industries)

- Stencil Reticle Case

Metrology Laser X-Y, LMS IPRO (Leica)



Stencil Pattern DUV Image for Inspection

Microscope:Nikon　　　　LU2000－－－－DUV　　　　-DUV wavelength　　　　266nm　　（　　（　　（　　（DUV　　　　Review　　　　Station））））　　　　-Mode: Transmission Image 　　　　　　　　　　　　　　　　　　　　 Reflection　　　　Image 　　　　

Transmission Image

-Sample 　　　　　　　　Si Stencil Reticle　　　　Si thickness 2μμμμm.

- Detectable Defect size:>50nm

1µm



Stencil Pattern SEM Image for Inspection

Secondary Electron Image Transmission Electron Image

Lines 0.9μμμμm　　　　and Spaces1.1μμμμm

Using Holon Stencil Mask Inspection Microscope.



Repair of Opaque and Clear Defect with FIB

◆Principle of the FIB etching

adhesionsubstrate

FIB

Ga+

Etching gasif need,

opaque defect

scan

milling reactive etching

Ga+

Ga++

substrate

deposition

precursor gas

FIBheating,if needed

adhesion

scan

◆Principle of FIB induced deposition

Opaque defect Clear defect



DLC Repair Patterns

Si membrane

Repair Pattern

SIM image of printable DLC repair patterns deposited by FIB(SII)across a 1μm width slot in a 2μm thick Si-membrane.The repair pattern: width 0.15μm, height 1μm.

1μμμμm

(Diamond Like Carbon)



Opaque Defect Repair on Stencil Reticle using FIB Milling

Afeter Opaque Defect Repair

Opaque Defect

1μμμμm0.5μμμμm

FIB Milling Condition FIB(SII) :Acc=30kVI=20pA



Outer Bath(stainless)

Transducer

Inner Bath(quartz

CleaningLiquid

Reticle

Inner Bathsupporter

Liquid(pure water)

◆◆◆◆ Schematic diagram of megasonic cleaner

　　　　Megasonic Cleaning



　　　　Megasonic Cleaning of Stencil Reticle

before megasonic cleaning

after megasonic cleaning

•Condition of megasonic cleaningfrequency = 1 MHzinput power = 300 Wcleaning liquid : surfactant (pH 12)

Particle (Al2O3) > 0.1um



Ar Aerosol Cleaning

Mass FlowMass FlowMass FlowMass FlowControllerControllerControllerController

Ceramic FilterCeramic FilterCeramic FilterCeramic FilterHeat ExchangerHeat ExchangerHeat ExchangerHeat Exchanger

NozzleNozzleNozzleNozzle

WaferWaferWaferWafer

Purge GasPurge GasPurge GasPurge Gas

Dry PumpDry PumpDry PumpDry Pump

Process ChamberProcess ChamberProcess ChamberProcess Chamber

Ar Ar Ar Ar GasGasGasGas

NNNN2222 GasGasGasGasCryogenic Cryogenic Cryogenic Cryogenic Refrigerator Refrigerator Refrigerator Refrigerator

XXXX----Y Scan Y Scan Y Scan Y Scan StageStageStageStage

Accelerator Accelerator Accelerator Accelerator NozzleNozzleNozzleNozzle

◆ Schematics of the Gas Flow (Sumitomo Heavy Industries, Ltd)

Mass Flow Mass Flow Mass Flow Mass Flow ControllerControllerControllerController

Ceramic FilterCeramic FilterCeramic FilterCeramic FilterNNNN2222 GasGasGasGas

NNNN2222 GasGasGasGas

Mass Flow Mass Flow Mass Flow Mass Flow ControllerControllerControllerController

Ceramic FilterCeramic FilterCeramic FilterCeramic Filter

Mass Flow ControllerMass Flow ControllerMass Flow ControllerMass Flow Controller



before cleaning after cleaning

Ar Aerosol Cleaning of Stencil Reticle (Al2O3, >0.1mm)



　　　　Reticle Case



Pattern Data Handling

Pattern Data Handling for EPL Stencil Reticle:

-Subfield Segmentation

-Complimentary Division/ Split

- Proximity Effect Correction

Several software venders have been developing new data handling software for EPL.



Layout dataLayout data Subfield segmentationSubfield segmentation

Data Post-Processing Software for EPL 1

Reticle imageReticle image



Stitching Stitching boudary boudary treatmenttreatment Proximity effect correctionProximity effect correction

Fuzzy boundaryFuzzy boundaryComplementary divisionComplementary division

Data Post-Processing Software for EPL 2



Summary1.There is no physical showstopper in reticle-process.

Technical issues are being discussed.

2. Reticle commercialization is in progress.

Mask manufactures have been developing EPL reticle.

3. Reticle infrastructure issues are fixed technically.

Commercial tooling should be discussed.

4. Data post-processing software is commercially available.

5. Reticle-related activities are waiting an external trigger

for the next step.

NGL Workshop, Pasadena, CA EPL Critical Review　　Aug-29-2001 1

Nikon NSRNikon

Experimental Data of Resist Exposure/Aerial Image

Nikon Corporation


Nikon NSRNikon

Nikon’s 100keV experimental column

Accelerating Voltage: 100kV.

Beam Current: 1-50µA

at the reticle.

Sub-field: 1mmx1mm

on the reticle.

NA:1-3 mrad.

Magnification: 1/4 with SMD

(Symmetrical Magnetic Doublet)

electron lens.


Nikon NSRNikon

Resist images exposed by Nikon’s 100kV column

60nm L/SNegative tone,

0.2µm-thickness80nm Holes

Positive tone,0.7µm-thickness

50nm iso-L & L/SNegative tone,

0.3µm-thickness

35nm iso-L

40nm iso-LNegative tone,

0.2µm-thickness


Nikon NSRNikon

Resist resolution for 1:2Holes/Spaces on the EPL

FEP-136(FUJIFILM ARCH)Thickness=500nmExpose dosage=9.0µC/cm2

Exposed with Nikon’s EPL experimental column(EB Acc=100kV)

90nm

80nm

70nm


Nikon NSRNikon

The DOF in EPLResist: NEB22(Sumitomo)

film thickness=260nmexposure dosage=47µC/cm2

Column condition:Nikon’s EPL experimental column

NA=1.3mradbeam current density=10mA/cm2


Nikon NSRNikon

Aerial Image Sensing technique

0

0.2

0.4

0.6

0.8

1

-40 -30 -20 -10 0 10 20 30 40Beam position(nm)

Nor

mal

ized

bea

m e

dge

prof

ile

12%

88%

13nm

Resolution for image blur measurement is <10nm and its repeatability is 3nm(3σ).

Rectangular EBMembraneknife edge

Scan

Scattered electrons

Limiting Aperture

diodedetector

Schematic diagram of Aerial Image Sensor Beam profile measurement


Nikon NSRNikon

Stigmator calibration by EB-AIS

05

1015202530354045

-20 -15 -10 -5 0 5 10 15 20

Focus setting (µm)

Imag

e bl

ur (n

m)

05

1015202530354045

-20 -15 -10 -5 0 5 10 15 20

Focus setting (µm）

Imag

e bl

ur (n

m)

(a) Before the optimization(Stigmator coil current: 41.2 mA)

(b) After the optimization(Stigmator coil current: 44.4 mA)

X direction Y direction

Nikon NSRNikonK.Okamoto & M. K.Okamoto & M. Sogard Sogard 11NGL 2001 Future EO (excerption )NGL 2001 Future EO (excerption )

Possibility of Throughput Enhancement Possibility of Throughput Enhancement (Future Electron Optics)(Future Electron Optics)

Kazuya OKAMOTO and Kazuya OKAMOTO and Michel R. SOGARDMichel R. SOGARD

Nikon Corporation, Nikon Research Corporation of AmericaNikon Corporation, Nikon Research Corporation of America

1.1. Motivation: Planar CMOS grand challengesMotivation: Planar CMOS grand challenges2.2. EPL feature and extensibility requestEPL feature and extensibility request3.3. EPLEPL--EO developmentEO development4.4. EO Strategy for high throughput EPLEO Strategy for high throughput EPL5.5. Dynamic image correctionDynamic image correction6.6. New high throughput systemNew high throughput system7.7. EPLEPL--EO extensibility (plan) EO extensibility (plan) 8.8. ConclusionsConclusions

AgendaAgenda


Source: International SEMATEC annual report 2000Source: International SEMATEC annual report 200020012001


Trade-off

Coulomb Effect Aberrations

CVAL●●●● Beam currentcation

EPLEPL--EO development EO development to achieve high resolution & high throughputto achieve high resolution & high throughput

ReductionReduction

Beam current Beam current margin margin increase increase

ReductionReduction

High beam currentHigh beam current

High throughputHigh throughput


EO extendibilityEO extendibilityBlur

NA

100nm

Reduction of the total blur

Aberrations Coulomb effect

70nm

50nm

Electron Optics Lens Electron Optics Lens TypeType

35nm

EOLEOL--100100

EOLEOL--7070

EOLEOL--5050

EOLEOL--3535


EO development EO development to achieve high throughputto achieve high throughput

1)1) Precise fabrication and assembly technology:Precise fabrication and assembly technology:Nikon’s strength.

2)2) Unique deflector structure similar to ideal cases: Unique deflector structure similar to ideal cases: IBM has invented.

3) 3) Fabrication error correction elements:Fabrication error correction elements:Stigmators, some correction elements, ….

4)4) CVAL trajectory optimization:CVAL trajectory optimization:Higher-order aberration consideration

5)5) Dynamic correction methodologyDynamic correction methodology6)6) Low onLow on--axis chromatic aberrations:axis chromatic aberrations:

Stencil reticle or thin-membrane recticle (DLC…)

((W. Stickel (IBM): JVST 1999)W. Stickel (IBM): JVST 1999)

Reduction of the geometric aberrationsReduction of the geometric aberrations

The target of an exposure system is to attain higher throughput and better resolution capability compatibly.


Optimization of every EO parameter:Column length LSystem magnification MSF size SFBeam energy VNABeam current I

High performance resist: high sensitivity <5uC/cm2 with high resolution

δ＝ＣL 5/4・I 5/6・M

V 3/2・α 3/5・SF 1/2Stochastic blur:

Deflectors (including electronics), body designReticle size, Chip size Aberration

HVPS, gun emittanceLow resist sensitivityWafer heating

ThroughputAberration

Reduction of the Coulomb blur:Reduction of the Coulomb blur:



40455055606570

5 7 9 11

blu

r(n

m)

Hollow beam illuminationHollow beam illumination

ReticleReticle

Blur (nm)Blur (nm)

NA (mrad)NA (mrad)

ConventionalConventional

HollowHollow

OffOff--axisaxis

OnOn--axisaxis

Hollow illumination is very effective to suppress the Coulomb efHollow illumination is very effective to suppress the Coulomb effect.fect.


Hollow beamHollow beam

Golladay (IBM) et al. Golladay (IBM) et al. JVST 18 (2000) 3072.JVST 18 (2000) 3072.

Point spread functionPoint spread functionPoint spread functions were convolved with idealized isolated liPoint spread functions were convolved with idealized isolated line and Linene and Line--space arrays space arrays consisting of 100 and 70nm equal lines and spaces. Hollow beam iconsisting of 100 and 70nm equal lines and spaces. Hollow beam illumination increases the llumination increases the average contrast : average contrast : by 9% for 100nm L/S, by 27% for 70nm L/S.by 9% for 100nm L/S, by 27% for 70nm L/S.

Uniform (0Uniform (0--10mrad)10mrad) Hollow (8Hollow (8--10mrad)10mrad)



Additional countermeasure for the Additional countermeasure for the space charge effectspace charge effect

Monte Carlo simulation of the projection system Monte Carlo simulation of the projection system have suggested that have suggested that aberrations induced by global spaceaberrations induced by global spacecharge can be as significant as beam blur resulting from charge can be as significant as beam blur resulting from stochastic interactions. stochastic interactions.

In Nikon EPL system:In Nikon EPL system:Stochastic Coulomb effect reductionStochastic Coulomb effect reduction

PLUSPLUSDynamic image correctionDynamic image correction for every subfor every sub--fieldfieldusing using Space Charge Correction GeneratorSpace Charge Correction Generatorin the data post processing software.in the data post processing software.


Dynamic Image CorrectionsDynamic Image Corrections

Required Dynamic Image Corrections in EPL:Required Dynamic Image Corrections in EPL:････････ Deflection CorrectionDeflection Correction

-- Image correction of deflection aberrations.Image correction of deflection aberrations.････････ Pattern Dependent CorrectionPattern Dependent Correction

-- Image correction of space charge effects.Image correction of space charge effects.

Dynamic Image Correction accuracyDynamic Image Correction accuracy is directly related is directly related to Stitching and Overlay accuracy.to Stitching and Overlay accuracy.

Deflection Aberrations:Deflection Aberrations:･･ Curvilinear Variable Axis Lens (CVAL) deflection opticsCurvilinear Variable Axis Lens (CVAL) deflection optics

almost eliminates deflection aberrations almost eliminates deflection aberrations which are not correctedwhich are not correctedby dynamic image correction.by dynamic image correction.


Calculation procedureCalculation procedureSpace charge effect aberration and Space charge effect aberration and

correctioncorrection--data extractiondata extraction


250µµµµm

250µµµµm

Calculation result of the SCE correctionCalculation result of the SCE correction

(a) Before correction and (b) After correction(a) Before correction and (b) After correction

Before correctionBefore correction After correctionAfter correction


1.Tone and material properties: positive and negative with 2.38%TMAH developer, CA type

2.Process: SLR (in the future: TBD)3.Resolution: less than 100nm, min. aspect ratio:3

(roughness<±±±±5% corresponding toΔΔΔΔCD±±±±10%)4.Sensitivity: 1uC/cm2 at 100kV (Eop)5.Contrast (γγγγ): >106.Dose latitude (% range atΔΔΔΔCD±±±±10%): >±±±±207.Profiles (degree): 87-908.PED stability: >3hr9.PEB sensitivity: <2nm/℃℃℃℃10.Plasma endurance: High11.Adhesion to substrate: High12.Ashing by O2 system plasma: Easy13.Pattern collapse: None14.Outgas during exposure process: None

EB resist requirement and statusEB resist requirement and status


The present EPL system (100kV, 250µm subfield size) could address the mass-production application for below the 50nm node, we have recently investigated the strategy of subfieldwe have recently investigated the strategy of subfield--size size expansion.expansion.

It resulted in a new concept based on the present EPL system, It resulted in a new concept based on the present EPL system, in which a smaller NA leads to both reduction of geometric in which a smaller NA leads to both reduction of geometric aberrations and the Coulomb blur simultaneously.aberrations and the Coulomb blur simultaneously.

New high throughput systemNew high throughput system

Further throughput improvement should be expected! Further throughput improvement should be expected!


In general, smaller NA optics means the larger Coulomb blur described in this formula.

However, we discovered the dependence in the formula on NA became saturated above a certain subfield size, and the blur became independent of NA for small NA.

In this concept, we could use a very small NA achieving very lowgeometric aberrations, while maintaining a high beam current.

New high throughput EPLNew high throughput EPLLarge SF EPL systemLarge SF EPL system

δ＝ＣL 5/4・I 5/6・M

V 3/2・α 3/5・SF 1/2


Small Blur Low geometrical aberration

Low Coulomb blurLow Coulomb blur

High ThroughputHigh Throughput

High sensitivity resist High sensitivity resist

Small overhead timeSmall overhead time

High performance stages for reticle and waferHigh performance stages for reticle and wafer

Throughput enhancement factorsThroughput enhancement factors

NikonNikon’’s missions mission

““IBM and NikonIBM and Nikon”” collaborationcollaboration

Large deflection >5mmLarge deflection >5mm

NikonNikon’’s hopes hope

33DD--CVAL optimizedCVAL optimizedPrecise EOPrecise EO--elements fabricationelements fabrication

> > Optimization of every parameterOptimization of every parameter> Large > Large subfieldsubfield sizesize

OptionsOptions


In conclusion, In conclusion, the excellent performance of highthe excellent performance of high--energy EPL has energy EPL has already been confirmed and we have developed a already been confirmed and we have developed a clear EO extensibility strategy. clear EO extensibility strategy.

Nikon/IBM also has several EPL concepts. We are Nikon/IBM also has several EPL concepts. We are mainly developing a volumemainly developing a volume--production machine production machine with a promising throughput >40wph for 300 mm with a promising throughput >40wph for 300 mm wafers.wafers.

Hence we are sure that EPL will be the principle Hence we are sure that EPL will be the principle candidate for the next generations of lithography. candidate for the next generations of lithography.

SummarySummary


Summary - Critical Issues 11) EPL Mask

- Standardization: Stencil: commercialized firstContinuous membrane: R&D

- Availability: Available from mask suppliers

2) Inspection/Repair/Cleaning of EPL Mask- Cleaning: Useful tool is available.- Inspection/Repair: POC works were done.

Commercialization Phase　 - Reticle handling: EPL reticle case is available.


Summary - Critical Issues 2

3) Extendibility

- Modeling results of future optics were introduced.

- Direct measurement result of image blur shows good agreement with simulation. The accuracy of Nikon’s modeling is confirmed.


Summary - Critical Issues 34) Stitching

- Preliminary data were shown.- Pattern edge modification decreases CD error

Data processing software: AvailableMask: Improving pattern fidelity

5) Wafer heating

Waiting for actual data from EB stepper.

6) Vacuum stage

Actual stages for EB Stepper were described.


Summary -Industry Participation

7) During this year the Semiconductor Industry has really started to participate in EPL technology development.

Documents

EPL Critical Review - SEMATECH · NGL Workshop, Pasadena, CA EPL Critical Review 08/29/01 1 EPL Critical Review Nikon/IBM/Selete Outline: 1. Introduction 2. Program Overview 3. Technology