- Status of Masks -

Current Status and Issues for ArF Extension

Nobuhito Toyama, Technical Manager

Member of the eBeam Initiative

2

Outline

• Roadmap & Challenges

• Complex Photomasks

• Approaches

• Trials & Examples

• Further Investigation

• Acknowledgement

3

Roadmap & ChallengesScaling & Scaling

2010 2011 2012 2013 2014

40

30

50

DPL

EUV

Computational Litho.

20

ITRS Roadmap : keep scaling

DRAM HPlogic Metal HPFlash HP

Logic Gate Length [year]

[nm]

Rapidly approaching a brick wall

ITRS Roadmap 2010

4

Roadmap & Challenges

40

30

50

Gate Length at IEDM : CMOS Devices and Technology

2010 2011 2012 2013 2014

20

2008 2009

logic Metal HP

Logic Gate Length

Computational Litho.

DPL or EUV

[year]

[nm]

from IEDM trend

Computational litho opportunities growing

32nm CMOS : still mainstream at IEDM

5

Complex Photomask

Computational Mask Correction more & more complex

conventional early OPC current advanced

more complex : # of features

smaller features

curved features

Computational Litho.

** virtual pattern

6

Complex Photomask

Computational mask correction

complex photomask data

Linearity# of fractured

featuresData

Handing

Inspection

Repair

insufficient

fidelity long writing time

(increasing cost)lower

Tputreduced

capability

Issues

7

Approaches

b) Linearity : small features smaller

a) Complex pattern fracturing : too many features

c) Process bias inconsistency : process bias induced number doubling

Linearity error ideal shape

linearity impacted

issues, and more

** virtual pattern

8

** virtual pattern

Complex Photomaskdesign ideal writing pattern expected fracturing

# of writing features

Courtesy of

Luminescent Technologies.

without correction

- uncontrollable CD

- unstable linearity

- less Depth of Focus

9

Approachesconventional fracturing

optimized fracturing

Fewer featuresoptimal effect

MB-MDP*overlapped shots

reducing writing time

litho-check

litho-checkEB writing check

** virtual pattern

bias

intelligentbias

*MB-MDP : Model-Based

Mask Data Preparation

10

Approaches

simplifying assist features

conventional fracturingMB-MDP

overlapped shots

with circular shape

Fewer features

optimal effect

reducing writing time

** virtual pattern

11

Independent "correction", "MDP" doesn't work

Approaches

- Linearity-aware Correction- Mask Process Compensation

- Litho-aware Correction- MDP-aware Correction

- Bias-aware Correction- Specific bias

correction

MDP

design

writing

a) Linearity : small features smaller

b) Writing time : too many features

c) Process bias inconsistency : process bias induced number doubling

measurement

supposed environment

correcteddata

MDP : Mask Data Preparation

12

1/3-1/4 features

Conventional

Fracturing

MB-MDP

overlapped shots

Trials & Examples

Resist

SEM MFG:75K

Courtesy of

D2S, Inc.

overlapped fracturing

Overlapped fracturing reduces the number of features

13

Trials & Examples

Confirmed : No alignment-error, No dimension error

inspected with conventional

fracturing

written with MB-MDP

overlapped shots

inspection

inspection

14

Trials & Examples

defect

locationdata

clipping

shape

correction

SEM

rendering

Rendering Acquired Image

repair

Courtesy of

Luminescent Technologies.

Repaired-image-reconstruction including

complex ones available

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Summary

- ArF will be extended more than ITRS expectations

- Photomask data is becoming more complex and intensive

- Successful trials are underway using overlapped shots

with MB-MDP

- Data correction & MDP need to be more closely linked

MDP : Mask Data Preparation

16

Probe further

- Practical process compensation approach

- Effective inspection & repair

- Linearity improvement as well

- Total load estimation

AcknowledgementLeo-san and Young-san : Luminescent Technologies;

Jan-san, Kuwano-san : D2S;

Ohara-san : Nippon Control System;

and DNP Japan related to this topic.