Defect inspection and characterization

on actinic blank inspection tool

Hidehiro Watanabe, Ichiro Mori EUVL Infrastructure Development Center(EIDEC):

Lasertec Corporation: Hiroki Miyai, Tomohiro Suzuki, Kiwamu Takehisa, Haruhiko Kusunose

EUVL symposium 2014

1. ABI tool development status

2. Defect printability

3. Defect characterization

4. Summary

Contents

1

EUVL symposium 2014

ABI tool development status

2

0%

20%

40%

60%

80%

100%

1 70

1.2 56

0.95 55

1 43

1 41

1 36

0.8 32

Height Width

Capture Rate, Programmed defects

ABI HVM Tool is ready to play an important role in phase defect control

Tsuneo Terasawa et al., Development of actinic full-field EUV

mask blank inspection tool at MIRAI-Selete, Proc. of SPIE

vol. 7271 (2009)

Dark field inspection

Actinic inspection

K. Goldberg et al., “Defect detection and inspection unmasked”,

IWEUVL, 2010

nm

nm

EUVL symposium 2014

EIDEC/Lasertec BI Program Schedule

3

2010 2011 2012 2013 2014 2015

Parts Fabrication

Development Improvement

EIDEC BI program1) started

Additional 1200x Review function

fabrication evaluation

Tool Design

1) BI Program: Blank Inspection program

Defect classification

Inspection started

Prototype tool for HVM 16nm hp Prototype tool upgrade

- Printability study

- Inspection capability

evaluation

- Location accuracy

evaluation

Achieved Basic performance

EUVL symposium 2014

ABI tool – inspection performance

4

0

50

100

150

200

250

Cumulative inspection area In

spe

ction

are

a / 1

04m

m2

- The ABI tool inspected more than 200 x104mm2 in one year.

- Signal intensity has been stable during this period.

- The ABI tool meets the 16nm-sensitivity requirement and is currently being

used for actual EUV mask blanks inspection.

The ABI tool has demonstrated its actinic inspection performance

through a year of operation.

EUVL symposium 2014

ABI tool - review function

5

0

20000

40000

60000

80000

100000 N

um

be

r o

f R

evie

ws

Cumulative number of reviews

- Actinic review is available for all defects detected by the ABI tool.

- The ABI tool performed more than 80,000 reviews in one year.

Actinic review function is crucial for understanding defect characteristics

1. ABI tool development status

2. Defect printability

3. Defect characterization

4. Summary

Contents

6

EUVL symposium 2014

Previous studies on printability of phase defect

7

Simulation study for Wafer impact as a function of ABI intensity

Noriaki Takagi et al., EIDEC symposium 2013

Relation between Printability simulation and experiment

Tsuneo Terasawa et al., EIDEC symposium 2013

Simulation on bridge defect

on wafer matched the

experiment result.

Simulation shows ABI signal

intensity proportionally co-

related to defect intensity on

wafer.

EUVL symposium 2014

Printing impact from ABI signal intensity

8

ABI signal intensity represents wafer printing impact

Width (nm)

ABI detection

threshold

10% CD error

for 16nm hp He

igh

t (n

m)

High

Low

Experimental ABI signal intensity

as a function of phase defect size

0 20 40 60 80

0

2

4

3

1

1. ABI tool development status

2. Defect printability

3. Defect characterization

4. Summary

Contents

9

EUVL symposium 2014

Defect characterization – ABI flow

10

Defect

Inspection

Low Magnification

Review

High Magnification

Review

-False elimination

-Phase / Amplitude

defect classification

1um 1um

-Pit/Bump classification

-Measurement of defect

location and size

-Defect map with DSI

(defect signal intensity)

Review of

each defect high

resolution

EUVL symposium 2014

Defect type EUV review DUV review

Phase Defect

(H2.4nm, W200nm)

Amplitude Defect

(H50nm, W76nm)

Phase / Amplitude defect classification

H22nm x W50nm carbon deposits

observable in DUV review

DUV review function

DUV

λ=193nm

defect

Schwarzschild

optics

11

With EUV and DUV reviews, Phase/Amplitude can be distinguished.

EUVL symposium 2014

Pit and Bump - Through focus images

12

3 um

PIT (-2.4x204nm)

BUMP (0.9x232nm)

-2.0um -1.0um 0.0um 1.0um 2.0um

Low magnification images

PIT (-1.7x63nm)

BUMP (0.9x72nm)

High magnification images 20 um

-2.0um -1.0um 0.0um 1.0um 2.0um

The position where the image focuses differs,

depending on whether the defect is pit or bump.

EUVL symposium 2014

No

rmal

ize

d in

ten

sity

PIT PIT1 (H1.7,W86)

PIT2 (H2.1,W98)

PIT3 (H2.4,W204)

-2.12 -1.62 -1.12 -0.62 -0.12 0.38 0.88 1.38 1.88 2.38 2.88

No

rmal

ize

d in

ten

sity

BUMP BUMP1 (H1.0,W97)

BUMP2 (H0.9,W116)

BUMP3 (H0.9,W232)

true 94%

6%

Pit / Bump classification function Through focus image analysis for pit/bump classification

judged form >100 samples of

programmed defect and native defect

Pit / Bump

classification result

13

miss judge pit

bump

With through focus image analysis, Pit/Bump classification is possible.

Threshold

-2 -1 0 1 2 Defocus /nm

Focus dependent intensity profiles for programmed phase defects

Details of focus dependency, see reference poster session “The influence of phase defect

characteristics on scattered light images in actinic dark field inspection” Noriaki Takagi, EIDEC

EUVL symposium 2014

Defect width

by AFM

72nm 101nm 108nm 120nm 154nm

Defect images

by high Mag.

review

Defect Diameter

from ABI images

55nm 76nm 95nm 112nm 120nm

Defect size measurement

14

Programmed phase defect images from high magnification optics

0

50

100

150

200

0 50 100 150 200

Defe

ct

siz

e f

rom

AB

I /n

m

Defect size from AFM /nm

Comparison of measurement results from ABI review and AFM

With ABI high magnification review images,

defect size measurement is possible.

1. ABI tool development status

2. Defect printability

3. Defect characterization

4. Summary

Contents

15

EUVL symposium 2014

Summary

16

1. The ABI HVM prototype performs EUV blank inspection and

review to assist the efforts to develop better EUV blanks.

2. ABI review images facilitate the following defect characterization,

which contributes to EUV blank defect management.

- Phase/Amplitude classification

- Pit/Bump classification

- Defect size measurement

EUVL symposium 2014

Acknowledgements

17

This work was supported by New Energy and Industrial

Technology Development Organization (NEDO) and Japan

Ministry of Economy, Trade and Industry (METI).

Thank you very much

for your attention.

This material contains confidential information.

Neither copy nor disclose to any third party is authorized

without prior written consent of Lasertec.

CONFIDENTIAL 18