2018 EUVL Workshop

O. Kostko, B. Xu, D. S. Slaughter, M. AhmedChemical Sciences Division, LBNL

K. D. Closser, D. L . Olynick, D. G. Prendergast, P. D. Ashby, D. F. Ogletree, Y. Liu

Molecular Foundry, LBNL

P. NaulleauCRXO, LBNL

W. D. HinsbergColumbia Hill Technical Consulting

G. M. WallraffIBM Almaden Research Center

Fundamental understanding of chemical processes in EUV lithography

2018 EUVL Workshop

Motivation

2D.F. Ogletree, Frontiers of Nanoscience, 11, 91 (2016)

Targeted EUV dose for 7nm node 40 mJ/cm2 = 27 photons/nm2

▪ Get fundamental understanding ▪ Increase sensitivity and resolution of EUV resist

H C N O F Mg Al Si Cl Fe Co Ni Cu Zn Br Cd In Sn Sb Te I

0

5

10

15

20

25

Ph

oto

ab

so

rptio

n c

ross s

ectio

n,

Mb

2p3d

4d

3p

EUV atomic cross sections(100 Mb = 1 Å2)

GlobalFoundries

2018 EUVL Workshop

How to Get Fundamental Understanding?

Step 1 PhotoionizationM + hν ➔ M+ + e-

e-γ

M+

Step 2Electronic RelaxationAuger process ?M+

➔ M++ + e-

e-

M++

Step 3Atomic RelaxationFragmentation?M+

➔ R1+ + R2

R1+

R2

3D.F. Ogletree, Frontiers of Nanoscience, 11, 91 (2016)

Gas-phasesingle molecule

Condensed resist

Processes After EUV Photon Absorption

2018 EUVL Workshop

How to Study?

Step 3 Atomic RelaxationFragmentation?M+

➔ R1+ + R2

Mass spectrometry:1. Fragmentation pattern after EUV photon absorption

4

Step 1 Photoionization

M + hν ➔ M+ + e-

Step 2 Electronic RelaxationAuger process ?M+

➔ M++ + e-

Photoelectron spectroscopy:1. Electron kinetic energies2. Electron yield

2018 EUVL Workshop

2-methylphenol 4-Cl-2-methylphenol2,3,5,6-Tetrafluoro-4-

(trifluoromethyl)phenol4-F-2-methylphenol 4-Br-2-methylphenol

4-I-2-methylphenol

F ICl Br

0

0

F

F3

F

F

F

Samples

5

H C N O F Mg Al Si Cl Fe Co Ni Cu Zn Br Cd In Sn Sb Te I

0

5

10

15

20

25

Pho

toab

sorp

tion

cro

ss s

ection

, M

b

2p3d

4d

3p

Compound Absorbed EUV photons (30nm), %

2-Methylphenol 11

4-F-2-Methylphenol 16

4-Cl-2-Methylphenol 11

4-Br-2-Methylphenol 13

4-I-2-Methylphenol 35

2,3,5,6-tetra fluoro-4-(trifluoromethyl)phenol 32

2018 EUVL Workshop

Auger

Step 1-2. Electron kinetic energies

2-methylphenol 4-Cl-2-methylphenol

2,3,5,6-Tetrafluoro-4-(trifluoromethyl)phenol

4-F-2-methylphenol

4-I-2-methylphenol

4-Br-2-methylphenol

Valence electronsSemi-core electrons

Photoelectron Spectroscopy

Valence electronsSemi-core electrons

6

• Number of absorbed EUV photons• Number of emitted e-

• Energy of emitted e-

0 20 40 60 80

0 20 40 60 80

0 20 40 60 80

0 20 40 60 80

0 20 40 60 80

0 20 40 60 80

F 2s

F 2p

I 4d

Br 3d

Kinetic Energy, eV Kinetic Energy, eV

Tunable parameters:

2018 EUVL Workshop

Step 3. Atomic relaxation

Mass Spectrometry: Photons

4-I-2-methylphenol

7

0 50 100 150 200

Inte

nsity,

a.u

.

m/z

C7H7OI+

I+

C7H7O+

C6H5+

C4H3+

C5H

4+

C3H4+

N2+

H2O+

parent

fragments

2018 EUVL Workshop

Condensed Resist?

8

• Photoabsorption, photoemission and Auger relaxation processes are almost unchanged

– dielectric environment reduces binding energies ~ 4 eV

– sharp lines are broadened

Step 4 Inelastic Scattering

M + e-➔ M+ + 2 e-

and more steps…

Mass spectrometry:1. Fragmentation pattern after

e- collision

e-

M+

e-

e-

• Inelastic electron scattering

– electrons interact with molecules

• Molecular fragmentation changes

– fragments are trapped in polymer matrix, may recombine or generate secondary reactions…

2018 EUVL Workshop0 2 4 6 8 10

0

5

10

15

20

Inte

nsity, a.u

.

Electron kinetic energy, eV

parent anion

I-

C7H

7O

-

0 20 40 60 80 100

Inte

nsity,

a.u

.

Electron kinetic energy, eV

parent C7H

7O I

m/z 107 C7H

7O

m/z 79 C6H

7

m/z 77 C6H

5

Step 4. Inelastically scattered electrons

Mass Spectrometry: Electrons

0 50 100 150 200 250

0

20

40

60

80

100

@20eV

4-iodo-2-methylphenol

Inte

nsity,

cou

nts

m/z

parent

fragments

Low energy electrons: dissociative electron attachment

9

C6H7

C6H5

2018 EUVL Workshop

uniform

core-shell

Diameter 50-500nm

How to Study Condensed Resist

10

(sub)nanometer inclusionsSi

Gas-phasesingle molecule

Condensed resist

Nanoparticle Beam

Nanoparticles of different morphology:

2018 EUVL Workshop

0 10 20 30 40 50 60 70

Inte

nsity,

a.u

.

KE (eV)

Photoelectron Spectra of Condensed Resist

11

E-beam resist: 4-Methyl-1-Acetoxycalixarene

Photon energy 320 eV

C 1s

Secondary electrons

e-hν

O. Kostko et al., JCP 147, 013931 (2017)0 20 40 60 80

Inte

nsity, a.u

.

Kinetic Energy, eV

80 60 40 20 0

Binding Energy, eV

PMMA

Valence electrons

Photon energy 92 eV

2018 EUVL Workshop

Collaborative Team and Instrumentation is the National Lab Strength

12

Management, Lithography and Materials

Deirdre Olynick FoundryPatrick Naulleau CXRO

AFM Characterization andMolecular Chemistry

Paul Ashby, Yi Liu Foundry

Spectroscopy and Chemical PhysicsBo Xu, Oleg Kostko, Musa Ahmed, Dan Slaughter

Chemical Sciences Frank Ogletree Foundry

TheoryKristina Closser, David Prendergast Foundry

Lithography and MaterialsGreg Wallraff IBM

Bill Hinsberg Col. Hill Tech. Consult