Mimicking very low energy secondary electron (< 20 eV)

interactions with novel photoresists Aniket Thete

Nanophotochemistry

ARCNL

Work Groups Network

Condensed matter physics

Bruno Rocha MartinsJarich HaitjemaYu ZhangRobbert BloemLotte MetzSander van LeeuwenAniket Thete

Prof. Fred Brouwer

Nanophotochemistry (ARCNL)

Dr. Sense JanVan der Molen

Daniël Geelen

Prof. Rudolf M. Tromp

2

LEEM for EUV lithography research

• Lower energy secondary electrons (LEE)

• Line edge roughness (LER)

• Mimicking LEE

=?

Resist

3

Sisubstrate

±Ve

0-100eV

EUV

hν91.7eV

Line edge roughness

Line edge blurring

Inelastic eventsInelastic events

EUV EUV

LEEMobjective lens

• low energy electron source

• tunable energy

• spectroscopy

Low-energy Electron Microscopy

Energy loss (eV)

Int.

Tim

e

Energy loss (eV)

magnetic

4

Typical experiment

• Contrast curve – vary dose and energy

• Electron energy loss spectrum (landing energy)

substrate

Resist

e-

-15kV + VE+-

Electron objective lens

5

First results on PMMA

PMMA

6

0 1 2

…

…

…

…

3 18 19 20 30

…

…

…

…

70 80 90

Electron Energy

Dose

µC/cm2

50µm

Optical image

14eV

90eV

Electron Energy loss spectrum PMMA

7

0 5 10 15 20 25 30 35

5

10

15

20

25

30

35

40

Tim

e (

s)

Energy loss (eV)

56.00

110.8

165.5

220.3

275.0

329.8

384.5

439.3

494.0

C

0 10 20 30 40 50 60

5

10

15

20

Tim

e (

s)

Energy loss (eV)

48.00

120.3

192.5

264.8

337.0

409.3

481.5

553.8

626.0

CE0 =20eV

-5 0 5 10 15 20 25 30 35 40

5

10

15

20

25

30

35

40T

ime (

S)

Energy loss (eV)

45.00

166.9

288.8

410.6

532.5

654.4

776.3

898.1

1020

CE0 =15eV E0 =30eV

0 10 20 30 40 50 60

20

40

60

80

100

Tim

e (

s)

Energy loss (eV)

45.00

182.5

320.0

457.5

595.0

732.5

870.0

1008

1145

CE0 =14eV

E0 =14eV

0 5 10 15 20 25 30 35

5

10

15

20

25

30

35

40

Tim

e (

s)

Energy loss (eV)

56.00

110.8

165.5

220.3

275.0

329.8

384.5

439.3

494.0

C

-5 0 5 10 15 20 25 30 35 40

5

10

15

20

25

30

35

40T

ime (

S)

Energy loss (eV)

45.00

166.9

288.8

410.6

532.5

654.4

776.3

898.1

1020

CE0 =15eV

0 10 20 30 40 50 60

5

10

15

20

Tim

e (

s)

Energy loss (eV)

48.00

120.3

192.5

264.8

337.0

409.3

481.5

553.8

626.0

CE0 =20eV E0 =30eV

0 10 20 30 40 50 60

20

40

60

80

100

Tim

e (

s)

Energy loss (eV)

45.00

182.5

320.0

457.5

595.0

732.5

870.0

1008

1145

C

Energy loss dataCurrent flowing through the resist Net beam current

PMMA (no graphene)

8

Resist

substrate

- - - - - - - - - - - - - - - -

14 eV15 eV

- + - - - - + - - - - - + - +-+ - + + + + + + - + ++ +

20 eV

14 V

Eeff= ~1eVEeff= 0eV

0 5 10 15 20

5

10

15

20

25

30

Tim

e (

S)

Energy loss (eV)

45.00

166.9

288.8

410.6

532.5

654.4

776.3

898.1

1020

C

Eeff= ~30eV

A. Thete, D. Geelen, S-J van der Molen, R. Tromp, Phys. Rev. Lett. 2017

Sn(oxo)-X (EUV –absorbing material)

15eV 20eV 30eV

9

E0=10eV

0 10 20 30 40 50 60

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

51.50

65.13

78.75

92.38

106.0

119.6

133.3

146.9

160.5

C

0 10 20 30 40 50 60

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

50.00

116.5

183.0

249.5

316.0

382.5

449.0

515.5

582.0

C

0 10 20 30 40 50 60

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

50.50

63.69

76.88

90.06

103.3

116.4

129.6

142.8

156.0

C

0 10 20 30 40 50 60

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

50.50

65.81

81.13

96.44

111.8

127.1

142.4

157.7

173.0

C

Charging when 𝐸0 < 15 eV

substrate

Resist

𝑉 = 10 V

substrate

Resist

e-𝐸0

substrate

e-𝐸0

Graphene

10

e-𝐸0 = 10 eV

Eeff = 0 eV

E0=10eV

0 10 20 30 40 50 60

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

51.50

65.13

78.75

92.38

106.0

119.6

133.3

146.9

160.5

C E0=10eV

0 10 20 30 40

2

4

6

8

10

Tim

e (

s)

Energy loss(s)

52.00

64.38

76.75

89.13

101.5

113.9

126.3

138.6

151.0

C

0 10 20 30 40

5

10

15

20

Tim

e (

s)

Energy loss (eV)

51.00

71.63

92.25

112.9

133.5

154.1

174.8

195.4

216.0

CE0=10eV

Summary and conclusions

• Positive /negative charging/ LEE interaction threshold

• Model has been formulated

• Charging control- Graphene

• Resist reaction with low energy electrons (< 5 eV)

• Resist charging relevant in EUV exposures(?)

• Effect on Line Edge Roughness

11

Thank you!Monday 26th 4:40 pm

10583-6 Zr- and Hf-based molecular hybrid materials as EUV photoresists

12

Supporting info.

13

With reduced current:threshold shifts downs-shape disappears

c = 0.2

If we are at positive charge (red plus), then we will suddenly drop tonegative charge (red circle) as conductance increases, and the s-curve shrinks. We then have a sudden drop in Eland.

o

+

0.0025V2 = (1-c.√(E0-V))*1.85

0.0025V2 = (1-c.√(E0-V))*1

0.0025V2 = (1-c.√(E0-V))/2

0.0025V2 = (1-c.√(E0-V))/4

0.0025V2 = (1-c.√(E0-V))/40

Or sample becomes more conducting:

0.00135V2 = (1-c.√(E0-V))

0.00250V2 = (1-c.√(E0-V))

0.00500V2 = (1-c.√(E0-V))

0.01000V2 = (1-c.√(E0-V))

0.10000V2 = (1-c.√(E0-V))+

+

0 10 20 30 40 50 60

0

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

50.50

63.94

77.38

90.81

104.3

117.7

131.1

144.6

158.0

Intensity

Landing energy (eV)

20eV

0 10 20 30 40 50 60

0

2

4

6

8

10

Tim

e (

s)

Energy loss (eV)

50.00

66.00

82.00

98.00

114.0

130.0

146.0

162.0

178.0

Intensity

Landing energy (eV)

30eV

+o

15