relationship between resist outgassing and activation...

2014 International Symposium on Extreme Ultraviolet Lithography, Washington, D.C., USA 28 Oct., 2014

Relationship between resist outgassing and activation energy for EUV and EB

Isamu Takagi, Takeshi Sasami, Toru Fujimori, Shinya Minegishi, Yukiko Kikuchi, Eishi Shiobara, Hiroyuki Tanaka, and Soichi Inoue

EUVL Infrastructure Development Center, Inc. (EIDEC)

Takeo Watanabe, Tetsuo Harada and Hiroo Kinoshita Laboratory of Advanced Science and Technology for Industry, University of Hyogo


Outline

2

Introduction

Objective of this work

Experiment & result

Relation between the outgassing and the activation energy of the protecting group

Relation between the outgassing and the quencher loading

Summary


Outline

3

Introduction


Experiment & result



Summary


Resist-induced Optics Contamination

4

Outgassing from EUV resist will result in optics contamination.

Before resists can be used on the EUV scanner, testing by witness sample (WS) method is necessary.

Mask

Projection Optics

Outgassing

Resist


Process Flow of Outgassing Test (WS Method)

5

Mask

Projection Optics

Outgassing

Resist

E-gun E-gun

WS

Resist

Ex)EUVOM-9000 Side-view

Outgassing


Process Flow of Outgassing Test (WS Method)

6

WS

Spectroscopic Ellipsometer

Witness Sample (WS)

Outgas

EUV light

or Electron beam (EB)

Contamination film

2. Film Thickness (FT)

measurement

WS

X-ray

e

XPS

4. Non-cleanable

element evaluation

WS

H-cleaner

Hydrogen radical

3. Hydrogen cleaning

1. Contamination

film growth

Contamination Growth (CG)

Spec. : OK or NG

dR/R calculated from XPS data

Spec. : OK or NG

If both OK, the resist can be exposed in scanner.


Outline

7

Introduction


Experiment & result



Summary


Objective of This Work

8

Clarify the relationship between outgassing and the protecting group.

Size of protecting group

Activation energy (Ea) for de-protection

Ex.) Components of model resist

Base resin PAG Quencher

Protecting group


Outline

9

Introduction


Experiment & result



Summary


Sample name A-1 B-1 C-1 D-1

Base resin

De-protection group (Mw) 148 162 176 82

Relative acid rate constant (k)

1.0 3.6 12.1 2.9

PAG 20 phr*

Quencher

0.1 mol for PAG

Composition of Model Resists in This Work

10

N

S+ C4F9SO3-

*per hundred resin

OH

O O

30 70

OH

O O

30 70

OH

O O

30 70

OH

O O

30 70


Outgassing Evaluation Tool and Condition

11

EB - EUVOM-9000 -

EUV - HERC* analysis tool -

Tool Geometry

Witness Sample (WS)

Ru 50 nm

Si-sub. Ru 5 nm

Si-sub. Mo/Si ML

*: HERC = High power EUV Resist Contamination

@ NewSUBARU BL9c

Undulator Light

WS

27o

320 mW/cm2

120 mW/cm2

Top-view

E-gun 2 keV

E-gun 0.25 keV

WS

Resist

Side-view

Evaluation tool

Resist process condition Substrate Si (w/ HMDS)

Resist thickness 60 nm

PAB/PEB 100oC 60s / 100oC 60s


Result of Contamination Growth (CG) Test

12

Big difference in CG depending on protecting group was observed.

0.64

4.44

15.38

7.39

0

5

10

15

20

A-1 B-1 C-1 D-1

CG

(n

m)

Note : All of CG data is scaled to get to 300 mm full wafer exposure.

EB


A-1

B-1

C-1

D-1

R² = 0.05

0

5

10

15

20

0 50 100 150 200 250

CG

(n

m)

Mw of de-PG

CG vs. Size of De-protection Group (De-PG)

13

No correlation observed between CG and the de-PG size.

EB


Relation between CG and k

14

A-1 B-1

C-1

D-1 R² = 0.90

0

5

10

15

20

0.0 5.0 10.0 15.0

CG

(n

m)

k

CG seems to correlate with k.

EB


B-1

D-1

0

5

10

0 50 100 150 200

CG

(n

m)

Mw of de-PG

Protecting Group Size Dependency

15

In the case of sample with similar acidic reactivity, the larger de-PG was observed to have lower CG.

EB


Relation between CG and k’

16

A-1

B-1

C-1

D-1

0

5

10

15

20

0.00 0.02 0.04 0.06 0.08

CG

(n

m)

k’

Considering both k and de-PG size parameters, strong correlation between CG and k’ observed.

This means higher outgassing risk at higher k’.

EB

k’ = k/(Mw of de-PG)


EB vs. EUV

17

A-1

B-1

C-1

D-1

A-1 B-1

C-1

0

1

2

3

4

0

5

10

15

20

0.00 0.02 0.04 0.06 0.08

CG

(n

m)

@ E

UV

CG

(n

m)

@ E

B

k’

EB

EUV based tests confirm that k’ can explain the relationship between CG and the characteristics of PGs. D-1 has not been evaluated at EUV. Future test is planned.

EUV

k’ = k/(Mw of de-PG)


Outline

18

Introduction


Experiment & result



Summary


Sample name A-1 / A-2 B-1 / B-2 C-1 / C-2 D-1 / D-2

Base resin

De-protection group (Mw) 148 162 176 82

Relative acid rate constant (k)

1.0 3.6 12.1 2.9

PAG 20 phr*

Quencher

(mol for PAG) 0.1 / 0.2 0.1 / 0.2 0.1 / 0.2 0.1 / 0.2

Composition of Model Resists in This Work

19

N

S+ C4F9SO3-

*per hundred resin

OH

O O

30 70

OH

O O

30 70

OH

O O

30 70

OH

O O

30 70


E0 Sensitivity

20

EB

A-1 A-2 B-1 B-2 C-1 C-2 D-1 D-2

E0

(uC/cm2) 1.63 2.63 1.23 2.68 1.31 2.66 1.06 2.17

0

0.5

1

1.5

2

2.5

3

A-1 A-2 B-1 B-2 C-1 C-2 D-1 D-2

E 0 (

uC

/cm

2)


Relation between CG and k’ in Quencher Loading Difference

21

Higher CG was found at increased k’ and quencher loading.

EB

A-2 B-2

C-2

D-2

A-1 B-1

C-1 D-1 0

20

40

60

80

100

0.00 0.02 0.04 0.06 0.08

CG

(n

m)

k’

Quencher = 0.2mol of PAG



What’s Contributor to CG ?

22

EB

Outgassing species was evaluated by Residual Gas Analysis (RGA)


Outgassing Species for Each Samples

23

39 51

78

109 119

186 0.0E+00

5.0E-07

1.0E-06

1.5E-06

2.0E-06

2.5E-06

12

14

16

18

11

01

12

11

41

16

11

81

amu

39 51

78

109 119 186

0.0E+00

5.0E-07

1.0E-06

1.5E-06

2.0E-06

2.5E-06

12

14

16

18

11

01

12

11

41

16

11

81

amu

39

51

78

109

119

186

0.0E+00

5.0E-07

1.0E-06

1.5E-06

2.0E-06

2.5E-06

12

14

16

18

11

01

12

11

41

16

11

81

amu

A few species attributed to the de-PG detected at A-2 and B-2.

Species attributed to the de-PG relatively abundant at C-2 and D-2.

Numbered amu (39,51,78,109,119 and 186) are attributed to the PAG

A-2 B-2 C-2

39

51 78

109 119

186 0.0E+00

5.0E-07

1.0E-06

1.5E-06

2.0E-06

2.5E-06

12

14

16

18

11

01

12

11

41

16

11

81

amu

Part

ial pre

ssure

(P

a) D-2

EB


Correlation between CG and Total Outgassing

24

CG correlates roughly with total outgassing which is the sum of partial pressures of each amu.

1.75 7.95

76.36

10.52

0.0E+00

5.0E-06

1.0E-05

1.5E-05

2.0E-05

2.5E-05

3.0E-05

0

20

40

60

80

100

A-2 B-2 C-2 D-2

Tota

l ou

tgas

sin

g (P

a)

CG

(n

m)

Total outgassing

CG

EB


Contributor to CG

25

1.75 7.95

76.36

10.52

0.0E+00

5.0E-06

1.0E-05

1.5E-05

2.0E-05

2.5E-05

3.0E-05

0

20

40

60

80

100

A-2 B-2 C-2 D-2

Tota

l ou

tgas

sin

g (P

a)

CG

(n

m)

Total outgassing

Total pressure of PAG contribution

CG

EB

The main contributor to CG is de-PG species.


Why the CG Increases Drastically at C-2?

26

A-2 B-2

C-2

D-2

A-1 B-1

C-1 D-1 0

20

40

60

80

100

0.00 0.02 0.04 0.06 0.08

CG

(n

m)

k’



E0=1.31 uC/cm2

E0=2.68 uC/cm2

Protecting group was de-protected by the increased dose?

EB


Why the CG Increases Drastically at C-2?

27

A-2 B-2

C-2

D-2

A-1 B-1

C-1

D-1 0

20

40

60

80

100

0.00 0.02 0.04 0.06 0.08

CG

(n

m)

k’



Protecting group was de-protected by the increased dose?

C-0 (with only base resin) had similar CG to background.

De-protection reaction is stimulated by acid generated from PAG, and not by the increased dose directly.

C-0 exposed

at 2.68 uC/cm2

(E0 of C-2)

EB

E0=2.68 uC/cm2


CG Proportionality to Dose

28

EB

Dose A

cid

concentr

ation

gen

era

ted

fro

m P

AG

Acid concentration

generated from PAG

CG

Dose

?


0

100

200

300

400

500

600

0 1 2 3 4

CG

(n

m)

Dose (uC/cm2)

C-2 : quencher = 0.2 mol

C-1 : quencher = 0.1 mol

CG Proportionality to Dose

29

CG is not proportional to the dose even while acid concentration is proportional to the dose.

Assumption: De-protection reaction rate is proportional to the power of acid concentration.

De-protection reaction equation

d[P]/dt = - Kdp ・[P] ・ [H+]m

[P] : normalized PG conc.

[H+] : normalized acid conc.

Kdp : de-protection rate const.

m : de-protection reaction order

t : time

EB

E0 = 1.31 uC/cm2

E0 = 2.68 uC/cm2


Outline

30

Introduction


Experiment & result



Summary


Summary

31

In order to understand the mechanism to mitigate outgassing, the relationship between outgassing and the protecting group was studied.

Results suggest that the risk of outgassing becomes higher in proportion to k’ ( = Relative acid rate constant / de-protection group size) .

Good correlation between CG and k’ was observed on both EB and EUV.

Drastic increase of CG confirmed to be mainly due to the de-PG, in a combination of low k’ and high quencher loading.


Acknowledgement

32

This work was supported by New Energy and Industrial Technology Development Organization (NEDO).

2014 International Symposium on Extreme Ultraviolet Lithography, Washington, D.C., USA 28 Oct., 2014 33

Thank you for your kind attention!

2014 International Symposium on Extreme Ultraviolet Lithography, Washington, D.C., USA 28 Oct., 2014 34

Supporting slide


Analysis of De-Protecion Reaction Kinetics

35

Ref.: O. Nakayama et.al., Proc. SPIE 6923, 135 (2008).

Monomer Each 2.73E-04 mol

Acid Benzoic Acid 1.1eq 2.73E-04mol

Solvent 1,1,2,2-tetrachloroethane-d2 0.69mL

NMR-tube

Heating 130 oC Time 0 s 300 s 600 s 1200 s

Cooling < 6 oC Time 5 min.

NMR analysis Methacrylic acid

Monomer

The reaction conversions were calculated from these integral values.

-6

-4

-2

0

0 500 1000 1500

LN(1

-X)

time (s)

-kt=LN(1-X) k:reaction constant t:time(s) X:conversion ratio

Large k = high acidic reactivity = Low Ea

relationship between resist outgassing and activation...

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