E-beam Defect Inspection of EUV Masks and Wafers

Scott Halle**, Fei Wang*, Ravi Bonam**, Hung-Yu Tien*, Karen Badger***,

Emily E Gallagher***, John Qi***, Daniel Corliss**, Derek Tomlinson*,

Chiyan Kuan*, Wei Fang*, Jack Y. Jau*

** IBM @ Albany Nanotech, NY USA

* Hermes-Microvision, San Jose CA USA

*** IBM Microelectronics , Burlington VT USA

Can e-beam Inspection Meet the Challenge?

Challenges

Tolerable defect sizes are less than the minimum feature size and Inspection time increases with decreasing defect sizes

Defect size

Optical

e-beam

Ins

pe

cti

on

Tim

e

Outline

• e-beam defect inspection for EUV lithography

• e-beam inspection system

• Die to Database (D2DB) Mode

• EUV Mask Defect Inspection

• EUV Wafer Defect Inspection

• Print Simulation

• Conclusion

e-beam Defect Inspection for EUV Lithography EUV Lithography Challenge

No Actinic Inspection

No Pellicle

e-beam Mask Inspection

High Sensitivity for identifying surface defects

e-beam Wafer Inspection

Potential for identifying phase defects

Process defects

Post develop wafers provide information on lithographic

printability

e-beam Inspection System

• Scanning Electron Microscope with

software for Die-Die inspection

• Virtualization SuperNovaTM system is

used for Die-Database inspection

• eTune – Used for Die-Die re-

inspection

• ADC workstation: Defect

Classification and Data Analysis.

eScan® 320xp Wafer Inspection

tool

eXplore® 5400 Mask Inspection

tool

Wafer/Mask

1

TFE source

Detector

Blanker

Stigmator

Laser

Magnetic Lens

1 2 2 3 3 4 4

e-beam column and

control

Die-DB Inspection

ADC

SuperNovaTM

eTune

Die To Database (D2DB) Mode

Absorber Defect Design Deviation Substrate Defect Absorber Nibbles

Die-Database method along with auto defect classification provides improved detection over Die-Die

Die-Database (D2DB) inspection can identify systematic and random

defects – critical advantage over Die-Die (D2D)

EUV Mask Inspection can be compared directly to Post OPC Mask

data

EUV Resist Wafer Inspection can be compared to Post OPC print

target data

EUV Mask Inspection Sensitivity -Hole 32x32nm (1X)

D2D and D2DB have comparable sensitivity on 32x32nm Hole for defects at 10 and 20nm pixel size

Program

Defects

Max

(30nm)

Decre

asin

g d

esig

n d

efe

ct siz

e

detection limit 6nm(1x)

10nm D2D

20nm D2D

10nm D2DB

20nm D2DB

CLR Ext.

G

CLR Ext.

H

Corner Int.Corner Ext.

D E

Pinhole

A

Pindot

B

OPQ Ext.

C

OPQ Ext.

F

Min.

(detectable)

EUV Mask Inspection Sensitivity – LS 28nm (1X)

Max

(30nm)

Program

Defects

detection limit 6nm(1x)

Min.

(detectable)

Decre

asin

g d

esig

n d

efe

ct siz

e

10nm D2D

(Mask)

10nm D2DB

(Mask)

5nm D2D

(wafer)

D2D and D2Db have comparable sensitivity on 28nm HP at 10 and 20 nm pixel size

Comparison of Inspection Results between EUV Mask and EUV Wafer

0

20

40

60

80

100

120

0 10 20 30

Cap

ture

Eff

icie

ncy (

%)

Design defect size (nm)

Capture Efficiency Comparison - Column C

Mask (nm)

Wafer (nm)

0

20

40

60

80

100

120

0 10 20 30Cap

ture

Eff

icie

ncy (

%)

Desing defect size (nm)

Capture Efficiency Comparison - Column E

Mask(nm)

C

OPQ Ext.

E

CLR Ext.

Aerial Image Simulation – Defect Printability on L/S 28 HP

10nm

Column A

(Clear)

Column E

(absorber)

5nm 7nm

10nm 7nm 5nm

Column Y - 15nm Column X - 22nm Column I - 5nm Column C, G – 5nm

Defect printability depends on defect types, resist, and process variations which can effect capture efficiency.

Diffused Aerial Image simulation of defects on calibrated computational model on the EUV ADT

Comparison of Inspection Results between EUV Mask and EUV Wafer

Capture efficiency (%) is the number of captured

defects divided by eligible defect number.

Mask defect capture efficiency is limited by mask

fidelity

Wafer defect capture efficiency can be limited by

• Tool printability for an illumination

• Resist and process variations

• Line edge roughness

0

5

10

15

20

25

30

35

0102030405060708090

100

0 5 10 15 20 25

Pri

nt

Sim

ula

tio

n d

efe

ct

siz

e (

nm

)

Ca

ptu

re E

ffic

ien

cy (

%)

Design Defect Size (nm)

Capture efficiency (%) vs. Defect size from print simulation - column I

Capture Efficiency (%) Print Simulation Defect size (nm)

Capture efficiencies on mask and wafer are comparable and 13nm design defects can be detected at

100% capture efficiency

Conclusion

Demonstrated e-beam defect inspection for EUV Masks and EUV printed

Wafer for both die to die (D2D) and die to database (D2DB) at comparable

sensitivity and capture efficiencies.

E-beam defect inspection for EUV masks shows capability of <20nm defect

size detection on multiple patterns, and identifies a variety of defect shapes

and types using automated defect classification system.

E-beam defect inspection for EUV resist exposure shows capability down to

10nm defect size detection, at the limit of Alpha Demo EUV Tool printing

capability, as shown by wafer print simulation studies.

Thank You!