Development of the Novel Evaluation Tool with an In-situ Ellipsometer for the Thickness

Measurement of the Contamination Originated by the High Power EUV Irradiation on EUV Resist

Takeo Watanabe1, Masaki Tada1, Yukiko Kikuchi2,

Toshiya Takahashi2, Kazuhiro Katayama2,

Norihiko Sugie2, Isamu Takagi2, Eishi Shiobara 2,

Hiroyuki Tanaka2, Soichi Inoue2,

Tetsuo Harada1, Hiroo Kinoshita1

1 Center for EUVL, LASTI, University of Hyogo 2 EUV Infrastructure Development Center (EIDEC)

Outline 1. Introduction 2. Overview of the novel contamination evaluation tool 3. Outgassing characteristics of the vacuum stage with the

motorized vacuum stage 4. Vacuum pressure of the main chamber 5. Carbon contamination thickness measurement using the

in-situ visible light spectroscopic ellipsometer 6. Summary

Background

The third EUVL issue is to develop which has the high sensitivity, the low line edge roughness, and the high resolution simultaneously. In addition, low outgassing characteristics.

・High sensitive

・Low LWR

・High resolution

・Low outgassing

Mask

Mirrors

Light source

EUV Lithpgraphy

Resist

The hydrocarbon outgassing species from the resist introduces the carbon contamination adhesion on mirrors and mask in EUV irraditaion. As a results, it affects on the lithographic throughput and the resolution . The outgassing study had been studied, however the relation ship between the outgassing species and the contamination thickness has not been clarified yet.

ASML suggested to use EB for the contamination adhesion evaluation.

The contamination evaluation by ASML

SPIE Feb.16, 2010, 7636-69_Poster I. Pollentier, A-M. Goethals, R. Gronheid, J. Steinhoff*, and J. Van Dijk*, IMEC, ASML

The difference in EUV and EB.

By EUV exposure By EB exposure

Re-action

Acid yield↑ ・Ionization ・Photoexcitation ・Inner shell excitation

Acid yield↓ ・Ionization

Sen-sitivity

Not completely same, some PAG has higher sensitivity in EUV.

Objective

1) The relationship between the outgassing species and the contamination adhesion would be clarified in EUV irradiation. And the contamination adhesion difference between in EUV and EB irradiations could be clarified.

2) The thickness of the carbon contamination would be measured by the in-situ ellipsometry in EUV irradiation.

3) The database construction of the contamination in EUV and EB irradiations would be performed. And the database is used for the design and developing the low outgassing resists.

EUV

Ellipsometry

Ellipsometry

Witness sample

Φ１inch

Resist/Wafer

Φ8inch

Loadlock

for wafer

85°

27°

Novel contamination evaluation tool

QMS

Ellipsometry (Source)

Ellipsometry (Analyzer)

Witness stage Resist stage

Witness and resist sample vacuum stages

0.00E+00

1.00E-10

2.00E-10

3.00E-10

4.00E-10

5.00E-10

6.00E-10

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

0.00E+00

1.00E-10

2.00E-10

3.00E-10

4.00E-10

5.00E-10

6.00E-10

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97 100

Before operation

During operation Conventional stepping motor

Novel stepping motor

Ion c

urr

ent（

A）

Mass number (amu) 100ms/amu

2.54×10-6 Pa

1.50×10-5 Pa

Outgassing characteristics using QMS

1x10-10

2x10-10

6x10-10

5x10-10

4x10-10

3x10-10

2x10-10

1x10-10

6x10-10

5x10-10

4x10-10

3x10-10

2x10-10

Vacuum Pressure and the Temperature of the Resist Rotation-Stage during the Operation

1.00E-06

2.00E-06

3.00E-06

4.00E-06

5.00E-06

6.00E-06

7.00E-06

8.00E-06

9.00E-06

1.00E-05

0

5

10

15

20

25

30

35

40

45

50

0 50 100

Temperature

Pressure

Time (min)

Tem

per

atu

re (ºC

) Pressu

ere (Pa)

(Motor Current 400 mA)

0.00E+00

5.00E-12

1.00E-11

1.50E-11

2.00E-11

2.50E-11

3.00E-11

0 20 40 60 80 100

0 min 30 min 60 min 90 min 120 min

Ion

cu

rre

nt

(A)

Mass number (amu)

The Mass Spectra of the Resist Rotation-Stage during the Operation

(Motor Current 400 mA)

5 x10-12

1.0 x10-11

1.5 x10-11

2.0 x10-11

2.5 x10-11

3.0 x10-11

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

0 20 40 60 80 100

Pre

ssu

re (

Pa

)

Time (hr)

The First Step to Achieve High Vacuum Pressure of the Main Chamber

Baking (150℃ 24 hrs)

3×10-6 Pa

Outgassing of QMS, NIG

1 x10-6

1 x10-5

1 x10-4

1 x10-3

1 x10-2

1 x10-1

EUV Exposure Intensity

On a witness sample 267 mW/cm2

On a resist sample 124 mW/cm2

(Depends on the refectivity of Mo/Si MLs)

NewSUBARU storage ring operation conditions ・1.0 GeV TopUp mode operation ・Storage ring electron beam current 250 mA

The ellispmeter CCD image on a witness sample

762 mm×762 mm

Phase-modulation-type spectroscopic ellipsometer Wavelegth region 450 nm～1000 nm Optical axis alignment of the ellipsometer: Witness sample stages Z, a, b-axes

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 20 40 60 80

Fitting c

2

Thic

kne

ss (

nm

)

Time (min)

Thickness (nm)

Kai^2

The in-situ carbon contamination thickness measurement

Fittng c2

Summary

1) The first achievement of the vacuum pressure of the main chamber was 3×10-6 Pa. The current base pressure is 8×10-7 Pa.

2) The specification of the in-situ visible spectroscopic ellipsometer satisfies the carbon contamination thickness measurement.

3) It was confirmed that using this system, the carbon contamination thickness measurement in high power EUV irradiation was achieved.

Future plan

With the same EUV power level in HVM, using the ion-counting-type QMS and the in-situ visible spectroscopic ellipsometer, the relationship between the resist outgassing species and the contamination adhesion could be clarified. And then the results might be feedback to the EUV resist design and development.

Acknowledgement

These results were obtained under the collaboration supports of NEDO and EIDEC, and the recomissioning by EIDEC.