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EUV Workshop / June. 12, 2008 1

Progress in EUV resist developmentT. Shimokawa, T. Kai, D. Shimizu, K. Maruyama, A. Saitou, Y. Hishiro†,

Semiconductor Materials Laboratory, JSR Corporation.†JSR Micro, INC.

2008 International Workshop on EUV LithographyJune. 12, 2008


Contents

Current status and issues of EUV resist

Material development

• Molecular glass (Noria)

• High acid generation resin

Summary


Resist Character Exposure result

APHS resin TPS PAG

EUV exposure result (Polymer-type)

30nmL/S 26nmL/S28nmL/S

Resolution limit: 26nmL/S, LWR@ 50nmL/S = 5.9nm

Resist A (PHS resin and TPS PAG) resolved 26 nm L/S patterns.

24mJ 24mJ 24mJLWR 7.7nm LWR 6.7nm LWR 7.1nm

(Evaluation Condition) MET at LBNL, on-Bare-Si, FT:70 nm, SB 130C-60s, PEB 130C-60s, development time 60s.


Evaluation results of EUV resistPerformance Resist A

Resist requirement(ITRS 2007)Character

BasePHS Polymer

TPS PAGType CAR

Resolution (1:1 L/S) 26 nm (resolution limit) 32 nm (with Process Margin)Sensitivity 24 mJ/cm2 5-30 mJ/cm2

LWR-3σ(Low frequency) 6.7 nm @28nm LS 1.7 nmOutgas 1.0×1014 -1015 molecules/cm2 6.5×1014 molecules/cm2*

EL 7.5% @30nm LS -DOF 0.06um @30nm LS -

*:SEMATECH’s spec for microexposure tool

For 32nmhp and beyond, sensitivity, LWR and resolution are needed further improvement. Additionally, outgass must be decreased.

The acceleration of novel material development is needed.


Contents





Summary



LWRLWR

ResolutionResolution

SensitivitySensitivity

OutgasOutgas

1.Molecular glass

2. Polymer bound PAG with anion pendant type

3.Bulky protecting group

4.Photo-destructive base

5.High acid generation resin

6.High quantum yield PAG with bulky structure

Issue Novel materialMain effect Concept•Smaller molecule Size

•Smaller grain size

• Homogeneity• Acid diffusion control

Volatile control from resin

Acid diffusion control

Higher acid amount

• Higher acid amount• Volatile control from PAG

Status of molecular glass and high acid generation resin are reported.


Concept of molecular resist

Large grain size Small grain size

Dev. Dev.

Large LWR Small LWR

exposure

Image figure

LWR improvement

Large grain size Small grain size

Dev. Dev.

Poor resolution High resolution

Small Grain (low molecular?)Large grain(ca.20nm PHS)

exposureResolution improvement

Large Grain(ca.20nm PHS)Small Grain (low molecular?)


It is possible to introduce various protecting group etc.

Higher thermal stability than other molecular glass

Noria1)

Noria was selected as molecular glass for our molecule resist.

Small molecular size（ca.2nm）

More rigid structure than other molecular glass

CharacterNoria

OHHO

HO

OH HO

OH

OH

HO

HO OH

OH

OH

HOHO

OHOH

HO OH

OH HOHO OH

OH OH

OHHO HClOHC-(CH2)3-CHO+

Resorcinol Glutaraldehyde(1,5-Pentanedial)

80 oC, 48 hin Ethanol

83% Yield

1) Nishikubo et al., Angew. Chem. Int. Ed. 2006, 45, 7948-7952


Noria - Physical property 1-

Physical property

PHS resinPHS resin NoriaNoria

Molecular weight (Mw) Approx.10000 Approx.2000Polydispersity >1.1 1.0Thermal stability 180℃（Tg） >300℃（weight loss)

Molecular size*(calculation) Approx.7 nm Approx.2 nm

Grain size** Approx.17 nm Approx.13 nm

Surface roughness*** Approx.14nm Approx.10nm

OHHO

HO

OH HO

OH

OH

HO

HO OH

OH

OH

HOHO

OHOH

HO OH

OH HOHO OH

OH OHOH

80

In collaboration with Prof. Nishikubo Kanawagwa Univ.

Noria showed smaller molecular size, grain size and surface roughness than that of PHS resin.

Noria has high thermal stability.

*Calculation method: MD, **Grain size was obtained from AFM image about protected PHS resin only and protected Noria only after coating, ***Surface roughness was obtained from AFM image about resist comprising of protected Noria and protected resin after half exposure.


Noria - Physical property 2-

Physical property

Other molecular glassOther molecular glass Protected Protected NoriaNoria

Distribution of protecting ratio

In collaboration with Prof. Nishikubo Kanawagwa Univ.

Protected Noria showed narrower distribution of protecting ratio than that of other molecular glass.

OR1R1O

R1O

OR1 R1O

OR1

OR1

R1O

R1O OR1

OR1

OR1

R1OR1O

O1ROR1

R1O OR1

OR1 R1OR1O OR1

OR1OR1

R1 : H or protecting groupR2 : H or protecting group

0 20 40 60 80 100

20

40

60

80

100

00 20 40 60 80 100

20

40

60

80

100

0

Protecting ratio(%)* Protecting ratio(%)**Ex

iste

nce

ratio

(%)

Exis

tenc

e ra

tio(%

)

Wide Narrow


28nmL/S 26nmL/S

24nmL/S

Exposure Result (Resolution)

(Evaluation Condition) MET at LBNL, on-BARC, FT:70 nm, SB 140C-90s, PEB 130C-90s, development time 60s.

Resist B showed good resolution.

EUVL

33mJ 33mJ

33mJ

Protected-Noria

TPS salt

S3

X

R1 : H or protecting group

OR1R1O

R1O

OR1 R1O

OR1

OR1

R1O

R1O OR1

OR1

OR1

R1OR1O

O1ROR1

R1O OR1

OR1 R1OR1O OR1

OR1OR1

Resist B


Exposure Result (ELBOW)

(Evaluation Condition) MET at LBNL, on-BARC, FT:70 nm, SB 140C-90s, PEB 130C-90s, development time 60s.

50 nm Elbow pattern

EUVL

Protected-Noria

TPS salt

S3

X


OR1R1O

R1O

OR1 R1O

OR1

OR1

R1O

R1O OR1

OR1

OR1

R1OR1O

O1ROR1

R1O OR1

OR1 R1OR1O OR1

OR1OR1

Resist B


(Evaluation Condition) MET at LBNL,on-BARC, FT:70 nm, SB 140C-90s, PEB 130C-90s, development time 60s.

Exposure Result (LWR)

LWR of resist B at 28nm L/S pattern was 6.1 nm.

EUVL

28nmL/S

50nmL/S 40nmL/S

32nmL/S

LWR=5.6nm LWR=6.4nm

LWR=6.3nm LWR=6.1nm

33mJ 33mJ

33mJ 33mJ

Protected-Noria

TPS salt

S3

X


OR1R1O

R1O

OR1 R1O

OR1

OR1

R1O

R1O OR1

OR1

OR1

R1OR1O

O1ROR1

R1O OR1

OR1 R1OR1O OR1

OR1OR1

Resist B


Litho performance of molecular resist applied Noria

Performance Resist A Resist B

Resist requirement(ITRS 2007)Character

BasePHS Polymer

TPS PAG

Noria(molecular glass)

TPS PAGType CAR CAR

Resolution(1:1 L/S)

26 nm(resolution limit)

28 nm(resolution limit)

<26 nm(pattern collapse)

32 nm (with Process Margin)

Sensitivity 24 mJ/cm2 33.0 mJ/cm2 5-30 mJ/cm2

LWR-3σ(Low frequency)

6.7 nm @28nm LS

6.1 nm @28nm LS 1.7 nm

Noria showed comparable litho performance to PHS resin.


Molecular glass - Future Action -

Molecular glassMolecular glass

1. Formulation optimization of Noria2. Molecular glass with PAG

Current system Current system New system New system

PAGPAG

Each components exists separately

Molecular glassMolecular glass

PAGPAG

PAG is integrated into Molecular glass

Optimization of formulation is ongoing.Molecular glass with PAG is under development.


Contents





Summary


e- + AG A + G-

High acid generation resin －Acid generation mechanism－

2.

3.

AG: Acid Generator、A: Decomposed fragment of AG, G-: Counter Anion of AG

HS unit is good unit for proton supply

Amount of secondary electron is increased by high absorption unit

To improve sensitivity

Increasing reaction rate of secondary electron with AG

1.

OHOH

+ e

OH OH

+ G HG+

EUV

XX is high absorption unit

X･+ x

*

OHHigh acid generation resin

Development status of high acid generation resin is reported.


Absorption of EUV1) Proc. SPIE. 3997, P.588, 2000.2) Atomic Data and Nuclear Data

tables. 54(2), P.181, 1993.

Atomic NumberPhot

oabs

orpt

ion

cros

s se

ctio

ns μ

(cm

2 /mol

)

CH

F

To increase absorption, N, O and F are available candidates

SHig

h Ab

sorp

tion

N

Si

Element Advantage Disadvantage

N 1.None 1.Act as quencher

O 1.Less reactivity with electron 1.Etching resistance

F1.High absorption

1.High reactivity with electron2. Outgassing (HF?)3.Etching resistance

Development status of F rich resin is reported.

O and F was selected as available candidates


Resin into which F is incorporated

OH

HS

Funit

PHS Resin=100（Ref）

HS/monomer with F=75/25

FT:100nm

Measured at Osaka university

Sample

Resin

PAGTPS-Tf

Composition Amount of generated PHS（Ref）=100 Ref

HS/monomer with F=75/25 20%UPHS/monomer with F=50/50 25%UP

Under 100nm FT, amount of generated acid increased with increasing ratio of fluorinated monomer. Litho performance is being evaluated.

Additionally, O rich resin is being prepared.

HS/monomer with F=50/50


Contents





Summary


SummaryCurrent status and issues of EUV resist

•For 32nmhp and beyond, sensitivity, LWR and resolution are needed further improvement. •Additionally, outgass must be decreased.•The acceleration of novel material development is needed.

Material development to improve resolution and LWRMolecular glass Noria

•Noria showed smaller molecular size, grain size and surface roughness than that of PHS resin.

•Noria showed high thermal stability.•Protected Noria showed narrower distribution of protecting ratio than that of other molecular glass.•Noria showed comparable litho performance to PHS resin.

Material development to improve sensitivity High acid generation resin

• Under 100nm FT, amount of generated acid increased with increasing ratio of fluorinated monomer.

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