assessment of aims™ euv and sharp actinic wavelength mask...

Assessment of AIMS™ EUV and SHARP actinic wavelength mask defect review tools for the evaluation of blank defect printability Erik Verduijn, Erik Hosler, Pawitter Mangat, Obert Wood Globalfoundries, Inc. Malta, NY 12020 USA

Renzo Capelli, Sascha Perlitz, Krister Magnusson, Markus Weiss, Dirk Hellweg Carl Zeiss SMT GmbH, Rudolf-Eber-Straße 2, 73447 Oberkochen, Germany

Vibhu Jindal SUNY Poly SEMATECH, 257 Fuller Road, Albany, NY 12203, U.S.A.

Markus P. Benk, Antoine Wojdyla, Kenneth A. Goldberg Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

EUV Symposium, Maastricht NL, October 5-7, 2015

Motivation

• Defect-free EUV masks are required, especially for logic devices.

– Optical inspection and wafer printability confirmation are not viable options for HVM

– Pawitter Mangat et al. PMJ 2015: “Having a bright-field actinic defect review tool will enable defect-free printability in HVM with confidence”

• Here, we compare the performance of SEMATECH’s SHARP actinic microscope with the AIMS™ EUV commercial actinic review tool being developed by Carl Zeiss SMT

• Both AIMS™ EUV and SHARP are actinic tools

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Blank Defect Review Procedure

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AIMS™ Review SHARP

Review

Litho

NA 0.33 0.25

0.33

0.25

0.33

Illumination Annular Conventional

Annular

Conventional

sin–sout 0.2–0.9 0.81

0.35–0.88

0.81

Blank inspection

(LT1350 & DFX40)

Mask fabrication

inspection (KT 6xx) & SEM review

Wafer exposure (NXE3100/3300)

Mask defect actinic review AIMS™

& SHARP

Correlation Analysis

Wafer SEM review

(KT eDR7100)

Use

bla

nk in

sp

ectio

n

de

fect c

oo

rdin

ate

s

Wafer print results shown for IMEC NA 0.25 NXE:3100 0.33 NA NXE:3300 exposures show equivalent defect detection results to this study

Shown for this study

GLOBALFOUNDRIES Public

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AIMS™ EUV actinic mask review tool

Performance Specifications

Target node 7nm logic (16nm hp)

Scanner emulation Up to 0.33 NA

CD Reproducibility ≤1.5 nm (3σ, mask level)

Run Rate standard

7 focus planes per site

≥ 27.5/hr

≥ 51/hr

> 38.5% pupil fill

> 77% pupil fill

Run Rate fast mode*

7 focus planes per site

*CD-repro = 1.8 nm (3σ)

≥ 55/hr >38.5% pupil fill

Illumination conditions available on prototype:

AIMS™ EUV prototype

Mirror optics based actinic mask defect aerial imaging

EUV camera field of view: 8x8 um (mask level)

NA 0.33 scanner illumination & projection emulation


SHARP Actinic Review Tool

8 sites/h

σ

z

13.5 nm

l T

0.25 0.33 0.35 0.42 0.50 0.625

NA 0.55/0.275 (4x)

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Mask Layout

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• GREMLIN4-LT mask (64P L/S)

L/S dies

Each die subdivided

into 64nm P H+V

Programmed

defect dies

Fill area

between dies

Large area ML/Ru-pad dies

for AFM roughness study

Outside pattern area GLOBALFOUNDRIES Public

Blank Defect Review Locations

7

-76000

0

76000

-76000 0 76000

51 67%

1 1%

3 4%

2 3%

19 25%

Blank Defect Distribution

In L/S area In programmed defect area

In fill area In Ru-pad area

Outside pattern area

BI: 76 blank defects total, post Ru Deposition


67%

1%

4%

3%

25%

Blank Defect Distribution

Inside pattened L/S area

In programmed defect area

In fill area

In Ru-pad area

Outside patetrn area

Example Defect Types

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Large-area L/S defect Bridge L/S defect Necking L/S defect

EUV absorbing defect in absorber area

EUV absorbing defect in reflecting ML/Ru

EUV absorbing defect in reflecting ML/Ru

Blank defect in pr. defect area not found

Shown for AIMS™

EUV absorbing defect in L/S

ID14

ID12

ID46

ID03 ID20 ID61

More EUV reflecting

Less EUV reflecting

2 μm details GLOBALFOUNDRIES Public

SHARP Rev.

AIMS™ Rev.

Wafer Rev.

29

4

2

Defect Review Comparison in L/S Area

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AIMS™ SHARP WAFER

Necking None Necking




Necking None None

Necking None None

Necking Necking None

0

0

1

0

• 64 % (33 /51) blank defects in L/S area are printing

– 100% (33/33) of these are found by AIMS™

– 88% (29/33) of these are found by SHARP

– 88% (29/33) of these are found by AIMS™ and SHARP

– AIMS™ finds all defects found on wafer and by SHARP

All non-commonality in necking L/S defects


Defects in L/S Area: Large-Area Defects

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All large area blank defects found by AIMS™ and SHARP review (6/6)

Excellent correlation between AIMS™, SHARP & wafer print

Multilayer damage more visible with actinic review than mask SEM

Actinic AIMS™

ID03

ID04

Actinic SHARP

ID11-13-6

ID11-13-08

Wafer SEM

ID03

ID04

ID57

Mask SEM

ID57


Defects in L/S Area: Bridging Defects

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All blank defects printing as bridges

were found by AIMS™ and SHARP,

also as bridges (13/13)

AIMS™

ID20

ID40

SHARP

ID11-13-22

ID11-13-30

Wafer

ID18

ID36

Limit case of bridging


Defects in L/S Area: Necking Defects

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100% of defects printing as necking defects

found by AIMS™, (14/14)

71% of defects printing as necking defects

found by SHARP, (10/14)

AIMS™

ID61

ID71

SHARP

ID11-13-40

ID11-13-44

Wafer

ID 54

ID61


Defects in Ru-pad Area

13

Absorber on reflecting Ru type defects

100% Found by AIMS™ (2/2)

50% (1/2) by SHARP

No defect found on wafer

AIMS™

ID12

ID34

Wafer

ID16

ID31

SHARP

ID11-13-16

IDNA

.

Low absorbance defects w/ small

background to defect intensity ratio not found by SHARP


Defects in Fill Area

14

Absorber on reflecting Ru type defects

50% found by AIMS™ and SHARP (2/4)

Non-critical defect; defects don’t printing

on wafer

AIMS™

ID14

ID38

SHARP

ID11-13-02

ID11-13-21

Wafer

ID14

IDNA

Wafer image not available Location checked, no def.


Defects Outside Pattern Area

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Absorber on absorber type

defects: dark on dark!

Low background-to-defect

intensity ratio

100% Found by AIMS™

(19/19), 63% (12/19) by

SHARP

Non critical defect; defects

don’t print on wafer

Low absorbance defects on dark absorber not found

by SHARP

AIMS™ has higher SNR for absorber-on-absorber defects

AIMS™

ID46

ID78

SHARP

ID11-13-34

ID47

AIMS™ only

ID74


Conclusions

Actinic mask review provides capability to forecast defect printability on wafer

All defects printing as bridges or large area defects found by both tools

AIMS™ & SHARP’s images reproduce wafer prints with high fidelity

To detect and quantify small line necking or dark-on-dark defects, stage accuracy and S/N ratio are critical

100% defect printability detection capability shown by AIMS™

Future work: Programmed defect actinic review by AIMS™ & SHARP

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assessment of aims™ euv and sharp actinic wavelength mask...

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