influences of polymer protection groups on euv...

DONGJIN SEMICHEM Co., Ltd

Jungyoul LEE, Jeongwoo Kim, Hyun-Jin KIM, Jae-Woo LEE,Deog- Bae KIM, Jaehyun KIM

Influences of Influences of PPolymer olymer PProtection rotection GGroups roups on EUV on EUV RResist esist PPerformanceserformances

Dongjin Semichem Co.,LTD.

ContentsContentsContents

1 IntroductionIntroduction

2 Experiments Setup Experiments Setup

3 Lithographic Results and DiscussionLithographic Results and Discussion

4 ConclusionConclusion

ContentsContents

5 AcknowledgementsAcknowledgements


2003 2004 2005 2006 2007

1. Source power and lifetime including condenser optics lifetime

1. Availability of defect free mask

1. Resist resolution, sensitivity and LER met simultaneously

1. Reliable high power source & collector module

1. Reliable high power source & collector module


2. Lifetime of source components & collector optics

2. Collector lifetime2. Resist resolution,

sensitivity and LER met simultaneously


3. Reticle protection during storage, handling and use





4. Projection and illuminator optics lifetime


4. Source power4. Reticle protection

during storage, handling and use


5. Resist resolution, sensitivity and LER 5. Source power


5. Projection and illuminator optics quality & lifetime


6. Optics quality for 32-nm half-pitch node

6. Projection and illuminator optics lifetime


Critical Issues of EUVL Voted by Key DevelopersCritical Issues of EUVL Voted by Key Developers


Sensitivity

Resolution LER

Acid Diffusion

Protection GroupDissolution Contrast

• Resolution

• LER (Line Edge Roughness)

• Sensitivity

• Out-gassing

Current EUVL Resist IssuesCurrent EUVL Resist Issues


2007

Resolution : 32nm

LER : 2.0nm

Sensitivity : 15mJ/cm2

Out gases :

1*1010~1011 molecule/cm2

Resolution

Line Edge Roughness

Sensitivity

Out-gassing

2008

Resolution : 2Xnm

LER : 1.5nm

Sensitivity : < 10mJ/cm2

Out gases :

1*1010~1011 molecule/cm2

EUVL Resist RequirementsEUVL Resist Requirements


Motivation and Experiment SetupMotivation and Experiment Setup

-- Goal of experiment :Goal of experiment :-> Investigation of the effect of different protection group on lithographic performance of EUVL resist

-- ExperimentExperiment-> Polymer preparation

- Protection type (Acetal and annealing types)- Protection ratio and acid diffusion length- Bulkiness and Free volume

-> Observation- Resist performance (Resolution, LER, Sensitivity, Out-gassing)


Sample Protection typeProtection

ratio Protecting groupPolymer structure

x /(x+y+z) R R’

Polymer A Acetal 26 Et Benzene

Polymer B Acetal 31 Et Benzene

Polymer C Acetal 35 Et Benzene

Polymer D Acetal 30 Bu Benzene

Polymer E Acetal 31 CH Benzene

Polymer F Annealing 24 - Benzene

Polymer G Annealing 30 - Benzene

Polymer H Annealing 34 - Benzene

Structures of PolymersStructures of Polymers

O

OR

OH

R'x y z

OH

R'O

O

x y z

Et = C2H5, Bu = C4H9, CH = C6H13


Mw PD Tg( ) Td ( ) Yield(%)

Acetal type Polymer A 9000 1.74 112

> 250

80

Acetal type Polymer B 9500 1.78 108 78

Acetal type Polymer C 9100 1.82 121 78

Acetal type Polymer D 8500 1.80 124 75

Acetal type Polymer E 9000 1.80 138 75

Annealing type Polymer F 9200 1.72 172 73

Annealing type Polymer G 9500 1.80 167 68

Annealing type Polymer H 9000 1.81 168 75

Properties of Prepared PolymersProperties of Prepared Polymers


Exp1. Exp1. Acid Diffusion Length MeasurementAcid Diffusion Length Measurement

PAG layer(modified TPS-Nf)

Polymer layer(300nm)

Exp

Bake

Acid diffusion

Dev

Thickness loss(Acid diffusion

Length)

Acid diffusion length measurement process

Hv


0

10

20

30

40

50

60

70

80 90 100 110 120 130 140

Temp(C)

Th

ick

ne

ss

lo

ss

(n

m)

Polymer A

Polymer B

Polymer C

Polymer D

Polymer E

Polymer F

Polymer G

Polymer H

Acid diffusion length measurement with PEB temperature for different type protection group

KrF Bulk Exp: 20mJ/cm2

Exp1. Exp1. Acid Diffusion Length MeasurementAcid Diffusion Length Measurement-- experimental resultsexperimental results


0

1 0

2 0

3 0

40

5 0

60

7 0

80 90 1 00 1 1 0 1 2 0 1 3 0 1 40

Temp( C)

Dif

fu

sin

le

ng

th (n

m)

Polymer F

Polymer G

Polymer H

Acetal type resistAcetal type resist Annealing type resistAnnealing type resist

0

1 0

2 0

3 0

40

5 0

60

7 0

80 90 1 00 1 1 0 1 2 0 1 3 0 1 40

Temp( C)

Dif

fu

sin

le

ng

th (n

m)

Polymer A

Polymer B

Polymer C

0

1 0

2 0

3 0

40

5 0

60

7 0

80 90 1 00 1 1 0 1 2 0 1 3 0 1 40

Temp( C)

Dif

fu

sin

le

ng

th (n

m)

Polymer B

Polymer D

Polymer E

Acetal Protection SizeAcetal Protection Size

Exp1. Exp1. Acid Diffusion Length MeasurementAcid Diffusion Length Measurement-- experimental resultsexperimental results

PEB temperature dependency of acid diffusion length

Major - Protection type (Annealing type > Acetal type)

Minor - Protection ratio & size


Exp2.Exp2. Litho ResultsLitho Results

Lithographic Performance of EUVL ResistLithographic Performance of EUVL Resist

-- Results of acetal and annealing type resist according to Results of acetal and annealing type resist according to the different protection groupthe different protection group

-- Effect of polymer bulkinessEffect of polymer bulkiness


Polymer A Polymer B Polymer C Polymer D Polymer E

HP 36nm

HP 34nm

HP 32nm

HP 30nm

HP 28nm

Litho Results According to Protection Group (I)Litho Results According to Protection Group (I)

Acetal type resistAcetal type resist

HP 32nm

HP 34nm

HP 36nm

HP 28nm

HP 30nm

HP 34nm

HP 32nm



Aetal type resistAetal type resistPolymer A Polymer B Polymer C Polymer D Polymer E

Protection Size small small small Mid Large

Protection % 26 31 35 30 31

Resolution >38nm <32nm 32nm <36nm 28nm

Dose(HP 50nm) 15mJ/cm2 16.2mJ/cm2 12.3mJ/cm2 21mJ/cm2 19mJ/cm2

3σ LER(HP 50nm) 7.4nm 4.2 - 5.1nm 5.3nm

Litho Results According to Protection Group (I)Litho Results According to Protection Group (I)


F G H

HP 50nm

HP 45nm

HP 40nm

HP 35nm Collapse

Annealing type resistAnnealing type resist

Annealing type resistAnnealing type resistPolymer F Polymer G Polymer H

Protection % 24 30 34

Resolution 40nm 35nm 35nm

Dose(HP 50nm) 15mJ/cm2 19mJ/cm2 18mJ/cm2

3σ LER(HP 50nm) 5.4nm 3.9nm 3.5nm

Litho Results According to Protection Group (II)Litho Results According to Protection Group (II)


Acetal vs. Annealing Type Resist

- Resolution of acetal type resist was better than that of annealing type resist

Acetal type polymer resists shows finer resolution than annealing type polymer ones.Acid catalyzed deprotection reaction is one of the main factors to determine the

resolution.Acid diffusion length in acetal type polymer was shorter than that in annealing type

polymerThe larger acid diffusion length resulted in image-blur!

- LER of annealing type resist was better than that of acetal type oneThis result can be explained by acid diffusion length.Generally, Acetal type resist shows higher LER than annealing type resist

-It was found that acid diffusion length in annealing type polymer was longer than that of acetal type one.

The longer acid diffusion resulted in line edge smoothening!

Litho Results According to Protection GroupLitho Results According to Protection Group


AcidDiffusion tonon-exposed Area

Acid diffusion to non-exposure area :

-> makes latent image blurred

Migration of photoacid :

-> difference bet. distribution of exposure energy

and final distribution of exposure photoproducts

This difference depends on :

-> photoresist chemistry and process condition

To prevent acid diffusion to non-exposed area :

-> increase acid size

-> decrease PEB temperature

-> incorporate base additives in photoresist

Latent Image Blurring by Acid DiffusionLatent Image Blurring by Acid Diffusion

Transitionregion

Exposed Areanon-exposed Area

Extent ofPolymer deprotection


Lithographic Performance of EUVL ResistLithographic Performance of EUVL Resist

-- Results of acetal and annealing type resist according to Results of acetal and annealing type resist according to the different protection groupthe different protection group

-- Effect of polymer bulkinessEffect of polymer bulkiness

Exp3.Exp3. Litho ResultsLitho Results


B D E

HP 36nm

HP 34nm

HP 32nm

HP 30nm

HP 28nm

Litho Results According to Protection SizeLitho Results According to Protection Size


HP 32nm

HP 34nm

HP 36nm

HP 28nm

HP 30nm

HP 34nm

HP 32nm

Aetal type resistAetal type resistPolymer B Polymer D Polymer E

Protection Size small Mid Large

Protection % 31 30 31

Resolution <32nm <36nm 28nm

Dose(HP 50nm) 16mJ/cm2 21mJ/cm2 19mJ/cm2

3σ LER(HP 50nm) 4.2 5.1nm 5.3nm


Pendentgroup

Pendentgroup

Pendentgroup

Pendentgroup

Low glass transition temp.

-> larger polymer free volume-> easy to acid diffusion

High glass transition temp.

-> less polymer free volume-> difficult to acid diffusion

H+H+

H+

H+H+

H+H+

H+

H+

H+

H+

Free volume change by different bulkiness of polymer side groups

Free Volume as an Acid Diffusion ChannelFree Volume as an Acid Diffusion Channel

H+H+

H+

H+H+

H+H+

H+

H+

H+

H+

Pendentgroup

Pendentgroup

Pendentgroup

Pendentgroup


Exp4.Exp4. Study of Resist OutStudy of Resist Out--gassinggassing

Out-gassing issue

- Out-gassing is one of the most important issues of EUVL resist.

-> The photo-induced out-gassing from resist film can be a major contamination in the vacuum environment.

-> The controllability of out-gassing materials are extremely important.

-> Bulky Acetal type resist showed less out-gassing than 6.5x1013 molecules/ .

Bulky Acetal Protection Type Annealing Protection Type

Out-gassing 5.03x1012 molecules/� 5.21x1013 molecules/�

Generally-accepted maximum value 6.5x1013 molecules/�

RemarkThese values are quite acceptable!!!

(Pohang accelerator Laboratory)

Resist typeOut-gassing


ConclusionConclusion

Resist performances of different protection types were well explained by acid diffusion length & polymer free volume.

Acetal type resists showed shorter acid diffusion than Annealing type ones.

Less acid-diffusive Acetal type resists showed high Resolution.

More acid-diffusive Anealing type resists showed better LER.

Large protection group resist shows better resolution than small size one.

Bulky protected polymer gave low outgassing during EUV exposure.


AcknowledgmentsAcknowledgments

We are much obliged to LBNL and Pohang accelerator Laboratory engineers, especially, Dr. Brian Hoef, Jin Ho An Ph.D., Hye-Keun Oh Ph.D. and Dr. Sang Sul LEE for all their supports.

Also, authors gratefully acknowledge technical supports and valuable discussion of colleagues in DONGJIN SEMICHEM Semiconductor Division for this work.

influences of polymer protection groups on euv...

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