strategy and feasibility of defect-free mask fabrication...

2009 EUV Symposium, Prague G-Number11

Strategy and Feasibility of

Defect-free Mask Fabrication to Enable EUVL

Ted Liang, Guojing Zhang, Sunny Son, Robert Chen, Sang Lee, Michael Leeson, Pei-yang Yan, Andy Ma, Long He,

Gilroy Vandentop

Firoz Ghadiali, Bennett Olson, Xiangyang Liu, Cheng-hsin Ma. Eric Lanzendorf, Barry Lieberman

Intel Corporation

Components ResearchTechnology and Manufacturing Engineering

Intel Mask Operations


OutlineOutline

Defect TypesDefect Types

Quantitative defect analysis with Quantitative defect analysis with existing tool setexisting tool set

Achieving zero defectAchieving zero defect

SummarySummary


EUV Mask Defect TypesEUV Mask Defect TypesDefects are more complex than those on 193nm mask

Cross-sectional view

Absorber (TaN, 80nm)

Ru cap (2.5nm thick)

Mo-Si ML (40-50 pairs, 280nm)

Substrate (LTEM, ¼”)

Conductive film (CrN, 70nm)

λ=13.5nm Schematic showing different types of defects

EUV mask defects are complexDifficult to differentiate and disseminate by wafer printNecessary to measure directly on the mask


Mask Defect ChallengesMask Defect ChallengesAchieving mask yieldAchieving mask yield

–– Detect every single defect above certain impact (Detect every single defect above certain impact (e.ge.g 10%10%ΔΔCD/CD)CD/CD)–– Go after every defectGo after every defect

Quantitative defect analysis is necessary to develop best Quantitative defect analysis is necessary to develop best known method (process, tool, procedure) to enable mask known method (process, tool, procedure) to enable mask yieldyield

–– Defect count, size, sources and dispositionDefect count, size, sources and disposition–– Only way to enable effective/efficient defect reductionOnly way to enable effective/efficient defect reduction

Challenges in fast yield learning for EUV maskChallenges in fast yield learning for EUV mask–– Blank defects: high count, majority with unknown propertyBlank defects: high count, majority with unknown property–– No tool at mask shop to measure phase or amplitude, materials coNo tool at mask shop to measure phase or amplitude, materials compositionmposition–– Insufficient Insufficient S/HS/H infrastructure to keep mask clean for printinginfrastructure to keep mask clean for printing

We must progress with what we have today in lieu of the We must progress with what we have today in lieu of the tool limitationstool limitations

–– Can we achieve zero defect to the limit of current tool capabiliCan we achieve zero defect to the limit of current tool capabilities?ties?


Blank ML Defect TrendBlank ML Defect Trend

~100 defects @50nm+~100 defects @50nm+Best blank ~10 defects @70nm+Best blank ~10 defects @70nm+

Size distribution

Need ~100X defect reduction to reach Need ~100X defect reduction to reach current tool limitcurrent tool limit

0

50

100

150

200

250

300

350

400

45 50 55 60 65 70 75SiO2 equivalent size (nm)

# of

Def

ects

at >

= gi

ven

size

LTEM/ML received in Q1-Q2with M7360 in spection

Total defect count

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

Jan-06

Jan-07

Jan-08

Jan-09

Jan-10

Jan-11

Jan-12

Def

ect c

ount

s

80nm defect size50nm defect sizeRM-for blank need by 2012

80nm50nm 45nm

35nm25nm2G tool1G inspection

tool

3G tool

M1350 M7360


Strategy of Defect StudyStrategy of Defect Study

Utilize full field mask as test vehicle: Utilize full field mask as test vehicle: –– ML blank: full plate inspection to map out defectsML blank: full plate inspection to map out defects

–– Pattern mask: clear field to sensitize defects and maximize detePattern mask: clear field to sensitize defects and maximize detectionction

Tools:Tools:–– Optimize current tool capability and develop Optimize current tool capability and develop BKMBKM

–– Identify critical needs for Identify critical needs for HVMHVM: Tools, process, procedure: Tools, process, procedure

Measurements Measurements –– inspection and characterization inspection and characterization metrology: metrology:

–– Focus on direct measurements on mask (mask qualification is doneFocus on direct measurements on mask (mask qualification is done at the at the mask shop, not at the wafer mask shop, not at the wafer fabfab))

–– Verification with wafer printVerification with wafer print


Mask Defect Disposition Flow at Mask Defect Disposition Flow at Mask ShopMask Shop

POR for 193nm maskPOR for 193nm mask–– All defects must pass AIMS in order to be All defects must pass AIMS in order to be dispositioneddispositioned

PatternInspection

Repair qual byAIMS

MaskRepair

Disposition by Simulation and AIMS

PatternInspection

As a workAs a work--around without EUV AIMS, use physical tools around without EUV AIMS, use physical tools ––SEM, AFM, blank and pattern defect overlaySEM, AFM, blank and pattern defect overlay

EUV mask, currently no AIMSEUV mask, currently no AIMS

PatternInspection*

Mask Repair;Qual by SEM/AFM

CharacterizationBy SEM, AFM

PatternInspection

ML blank defect tracing/separation


Pattern Inspection and Defect SizingPattern Inspection and Defect Sizing● Defect sizing with SEM vs. pattern inspection tool

– Inspection tool does not size defects

● SEM and AFM are sufficient for pattern defect disposition with aid from printability modeling


● Defect from pattern and blank – 19 total defects from pattern inspection– 16 matched to ML blank defects– 3 are real pattern defects

Automatic Defect Overlay for Defect ClassificationAutomatic Defect Overlay for Defect Classification

Defect size and height

● Pattern inspection detects most large blank defects (embedded particles)

Pattern inspection19 defects

ML blank inspection ~100 defects

16 defects traced to ML blank 3 real absorber defects

50

100

150

200

250

300

350

400

3 5 7 9 11 13 15 17 19 21 23

Inspection pixels

SEM

siz

ing

(nm

)

10

45

80

115

150

185

220

255

AFM

Ht (

nm)

SizeHeight

50

100

150

200

250

300

350

400

3 5 7 9 11 13 15 17 19 21 23

Inspection pixels

SEM

siz

ing

(nm

)

10

45

80

115

150

185

220

255

AFM

Ht (

nm)

SizeHeight


Assessing Potential Impact to PrintAssessing Potential Impact to Print● Total of 19 total defects at pattern inspection

● Impact depends on location – Must eliminate every large defect

3 absorber defects are all repairable

9 of 16 ML blank defects are printable

7 of 16 blank defects (covered by absorber)


Total Pattern Defect ReductionTotal Pattern Defect Reduction

● >4X reduction in total defects >40nm● Best achieved: 8 total defect >40nm

Jan’09

1st pass defect reduction trend

Lot/time sequence

Def

ect c

ount

1

10

100

1000

Dark field test maskClear field test mask

Total count >40nmTotal count >70nm


Lot/time sequence

Def

ect c

ount

1

10

100

1000

Clear field maskDark field mask

Jan’09


Lot/time sequence

Def

ect c

ount

1

10

100

1000

Dark field test maskClear field test mask

Total count >40nmTotal count >70nmTotal count >40nmTotal count >70nm


Lot/time sequence

Def

ect c

ount

1

10

100

1000

Clear field maskDark field mask


Achieving Zero Defect Achieving Zero Defect –– Pattern RepairPattern RepairExample 1: Defect caused 10% Example 1: Defect caused 10% ΔΔCDCD/CD/CDFully repaired as by Fully repaired as by ADTADT printprintSEM + AFM sufficient for SEM + AFM sufficient for patternpattern repair repair validationvalidation


Achieving Zero Defect Achieving Zero Defect –– Pattern RepairPattern RepairExample 2: Defect caused 15% Example 2: Defect caused 15% ΔΔCDCD/CD/CDFully repaired as by Fully repaired as by ADTADT printprint


Repairing ML BlankRepairing ML Blank--caused Defectcaused DefectComplex defectComplex defect

Defect caused by large CDefect caused by large C--containing containing particulate on ML blank resulting in thin particulate on ML blank resulting in thin absorberabsorber

SEM + AFM are used to guide repairSEM + AFM are used to guide repair–– Defect natureDefect nature–– Repair by depositionRepair by deposition


120nm tall particle embedded in ML blank; Caused bridging120nm tall particle embedded in ML blank; Caused bridgingSEM + AFM not sufficient to guide repairSEM + AFM not sufficient to guide repairNeed composition to dial in repair etch chemistryNeed composition to dial in repair etch chemistry

Repairing Embedded ML Blank DefectRepairing Embedded ML Blank Defect

Resist print improvedResist print improved–– Pass/fail depends on device layerPass/fail depends on device layer

Compensation is needed for Compensation is needed for incomplete defect removalincomplete defect removalML blank must be free of ML blank must be free of large embedded particleslarge embedded particlesAIMS is a mustAIMS is a must--have to have to monitor and qualify repairmonitor and qualify repair


Repair Qualification DiscussionRepair Qualification DiscussionNonNon--pure absorber defect, caused pure absorber defect, caused bridgingbridgingIs repair good enough?Is repair good enough?

SEM alone not sufficientSEM alone not sufficient

AFM difficult to measure AFM difficult to measure at the edgeat the edge

AIMS is needed to AIMS is needed to provide immediate provide immediate feedback to ensure feedback to ensure successful repair successful repair


ZeroZero--defect Handling and Storage defect Handling and Storage Zero particle adders can be achieved with RSP, but not always zeroStandard EUV reticle carrier sPodwith inner pod to further prevent particlesNeed to build and test infrastructure around ADT to facilitate learning

– Including cleaning tool

ReticleFacing down

Transfer between buildings


0.0E+00

5.0E+03

1.0E+04

1.5E+04

2.0E+04

2.5E+04

3.0E+04

0 10 20 30 40 50 60

Height (nm)

Are

a (n

m^2

)

Small 3D-like defectsMetal oxides (Ti, Cr, Ta)

Thin flat 2D-like defects (C-containing)

50nm eq-Dia.

80nm eq-Dia.

Challenges in Mask CleaningChallenges in Mask Cleaning

-505

101520

0 0.5 1(μm)

Hei

ght (

nm)

Defect #24, pixel 7

-505

101520

0 0.5 1(μm)

Hei

ght (

nm)

Defect #222, pixel 12

Frequent cleaning poses additional challenge to mask lifetime– Avoid Ru-ML damage

Biggest challenge: avoiding adders

Common adders are 2D-like carbonaceous and 3D-like oxidesKey focus: Particle filtration and removal efficiency

2009 BACUS paper


SummarySummaryEUV mask defects are complex in types and root causesEUV mask defects are complex in types and root causes

–– Direct measurements is necessary for defect reduction and mask qDirect measurements is necessary for defect reduction and mask qualificationualification

We have developed best known methods for We have developed best known methods for quantitativequantitative defect defect understanding and reduction by optimal use of current tool setunderstanding and reduction by optimal use of current tool set

We have demonstrated full loop device pattern repair as verifiedWe have demonstrated full loop device pattern repair as verifiedwith with ADTADT printprint

–– SEM + AFM capable to guide repair for majority of defects, but nSEM + AFM capable to guide repair for majority of defects, but not sufficientot sufficient

–– AIMS is in critical need, the first priority tool for defect AIMS is in critical need, the first priority tool for defect dispositiondisposition

–– Repair + compensation is necessary for ML blank defectsRepair + compensation is necessary for ML blank defects

ML blank defects must be reduced to <<10 and all need to be ML blank defects must be reduced to <<10 and all need to be smaller than primary mask patterns to smaller than primary mask patterns to be be compensatablecompensatable

–– Current inspection tool is deemed capable to support this effortCurrent inspection tool is deemed capable to support this effort for blank suppliersfor blank suppliers

–– Highest risk for ML blanks will likely be large embedded particuHighest risk for ML blanks will likely be large embedded particulate defects vs. small late defects vs. small phase defectsphase defects


AcknowledgementsAcknowledgements

Intel Components Research – Armando Cobarrubia, John Magana, Seh-Jin Park

Intel Mask Operations–– Nathan Wilcox, Andrew Nathan Wilcox, Andrew JamielsonJamielson, Chang, Chang--Ju Choi, Ju Choi,

YiYi--Ping LiuPing Liu

Carl Zeiss for supporting repair test– Thorsten Hofmann, Klaus Edinger, Kinga Kornilov

strategy and feasibility of defect-free mask fabrication...

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