AAAAA - euvlsymposium.lbl.goveuvlsymposium.lbl.gov/pdf/2006/posters... · AAAAA 3/17 Oct. 16, 2006...

Photomask Team / MEMORY DIVISION

2006 International Symposium on EUVL

AAAAA

Oct. 16, 2006

Photomask TeamSemiconductor R & D Center

Samsung Electronics Co. Ltd &Samsung Advanced Institute of Technology

EFFECT OF CURRENT CLEANING PROCESSES ON REFLECTANCE OF EUV MASK

Jaehyuck Choi,, Sungmin Huh, Segun Moon, Jinhui Kim, Soowan Koh, Eun-jung Kim, Sunghun Chi, Byungcheol Cha,

Dongwan Kim, Jeong-woo Lee, Seongwoon Choi, Woosung Han



AAAAA

2/17 Oct. 16, 2006

ContentsContents

1. Oxide Layer and Reflectivity for EUV Mask

2. Sample Preparation

3. Reflectivity Analysis

4. Ellipsometry Analysis

5. Conclusions



AAAAA

3/17 Oct. 16, 2006

1. Oxide Layer and Reflectivity for EUV Mask

Interfacial layer of Mo-on-Si is thicker than the Si-on-Mo interface- Atomic weight difference: Mo (95.94) vs. Si (28.09)- The crystalline Mo is more densely packed than amorphous Si.

Factors that affect M/L Reflectivity

Capping layer oxide layer thicknessCapping layer materialsCapping layer thickness

Mo layer thickness / (Mo + Si) layer thicknessMo layer + Si layer thickness (period)

Mo/Si interfacial layer thicknessSi/Mo interface layer thickness

Mo layer + Si layer pair No.

Incident light wavelengthIncident angle

Capping layer surface roughness

Silicide (1.7 nm)

SiO2 (1.2 nm)

Si (2.8 nm)

Mo (2.3 nm)Silicide (0.6 nm)

Si (2.2 nm)



AAAAA

4/17 Oct. 16, 2006

EUV Reflectivity vs. TEUV Reflectivity vs. Toxox & T& Tcappingcapping

When the thickness of oxide layerexceeds 2 nm, it starts to affect

the total EUV Reflectivity

In order to understand how the Capping oxide layer &

the Capping layer thicknessesaffect the EUV Reflectivity,

the reflectivity was calculated

We need to find out optimal cleaning processes that

do not affect the Reflectivity



AAAAA

5/17 Oct. 16, 2006

Definition of Rmax, FWHM, & CW



AAAAA

6/17 Oct. 16, 2006

2. Sample Preparation

EUV mask fabrication

EUV mask blankfrom blank vendor

e-beam writing

absorber etch

resist strip & cleaning

defect inspection

repair

buffer etch

clean

final inspection

EUV mask Cleaning

Bath : SPM, SC-1

Spin :O3 Water, H2 Water

Dry : Asher



AAAAA

7/17 Oct. 16, 2006

Ozone Water

00.10.20.30.40.50.60.7

12.8 13 13.2 13.4 13.6 13.8 14 14.2

Wavelength (nm)

Ref

lect

ivity

O3

Direct oxidation by “Ozone”

HO• Indirect oxidation by “Ozone”

C=C C-H C-OH C=O OH-C=O

Olefin Alkane Alcohol KetoneCarboxylic

acid

AlcoholKetone

Carboxylic acid

AlcoholKetone Carboxylic acid Soluble

in DIW

Superior oxidant than “Ozone”

Oxidation

SiO3 Water

Organic contaminant SiO2

A oxide layer is made by O3 water

Change of Reflectivity

Ozone Water3. Reflectivity Analysis



AAAAA

8/17 Oct. 16, 2006

Oxidation

SiH2SO4

From SPM


A oxide layer is made by SPM


Organic contaminants ⇒ CO, CO2, H2O

SPM

00.10.20.30.40.50.60.7

12.8 13 13.2 13.4 13.6 13.8 14 14.2

Wavelength (nm)

Ref

lect

ivity

SPM



AAAAA

9/17 Oct. 16, 2006

Ashing

00.10.20.30.40.50.60.7

12.8 13 13.2 13.4 13.6 13.8 14 14.2

Wavelength (nm)

Ref

lect

ivity

Plasma AshingO2

O (1D) O (1D)

Ionizing Radiation

CkHmOn ⇒ Ck’Hm’On’ ⇒ CO, CO2, H2O

O (1D) O (1D)

A oxide layer is made by Ashing


SiO (1D)

from Ashing


Oxidation



AAAAA

10/17 Oct. 16, 2006

Si

-- -------

- - - - - -

-

- - - - - -

OH- from SC-1

OH- from SC-1

H2O2 from SC-1

particle SiO21) Oxidation

2) Lift Off

3) Repulsion

The oxide layer made by H2O2 is etched by NH4OH

Almost no change of Reflectivity

SCI

00.10.20.30.40.50.60.7

12.8 13 13.2 13.4 13.6 13.8 14 14.2

Wavelength (nm)

Ref

lect

ivity

SC-1



AAAAA

11/17 Oct. 16, 2006

-- -------

- - - - - -

-

- - - - - -

H2 Water

1) Lift Off

2) Repulsion

H2 Water

No oxide layer is made by H2 Water

Almost no change of Reflectivity

H2 Water

00.10.20.30.40.50.60.7

12.8 13 13.2 13.4 13.6 13.8 14 14.2

Wavelength (nm)

Ref

lect

ivity

H2 Water



AAAAA

12/17 Oct. 16, 2006

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

ΔR

max

-0.15

-0.1

-0.05

0

0.05

0.1

ΔFW

HM

, ΔC

W

Rmax FWHM Centroid Wavelength

O3 water

SPM SC-1 Ashing H2 water

O3 water SPM Ashing SC-1 H2 Water

Δ Rmax (%) - 0.51 - 0.37 - 1.12 0.12 - 0.08

CW (nm) - 0.13 0.01 0.083 0.01< ~ 0

FWHM (nm) - 0.01 - 0.01 ~ 0 ~ 0 ~ 0

Serious (oxidation) Moderate (oxidation) Moderate (etching)



AAAAA

13/17 Oct. 16, 2006

Oxidant agent4. Ellipsometry Analysis

SPM

O3 Water

Ashing

a-Si(56.4%)+SiO2(43.6%)

ML

97.73 Å

Before Cleaning SiO2

ML

8.44 Å

94.19 Åa-Si(70.9%)+SiO2(29.1%)

After Cleaning

Δ SiO2

Δ a-Si

a-Si

SiO2

ML

41.79 Å

62.30 Å

Before Cleaning

a-Si(56.4%)+SiO2(43.6%)

ML

97.73 Å

After Cleaning

Δ SiO2

Δ a-Si?

a-Si

SiO2

ML

41.33 Å

60.51 Å

Before Cleaning

a-Si(72.3%)+SiO2(36.7%)SiO2

ML

18.43 Å

74.90 Å

After Cleaning

Δ SiO2

Δ a-Si

Δ SiO2

Δ a-SiΔ Rmax Δ SiO2 CW Δ a-Si CW



AAAAA

14/17 Oct. 16, 2006

Etching agent

a-Si

SiO2

ML

40.30 Å

62.00 Å

Before CleaningSiO2

ML

38.87 Å

61.96 Åa-Si

After CleaningSC-1

Δ SiO2Δ a-Si

a-Si

SiO2

ML

38.87 Å

61.96 Å

Before Cleaning

a-Si(72.3%)+SiO2(36.7%)

SiO2

ML

34.00 Å

61.00 Å

After CleaningH2 Water

Δ SiO2Δ a-Si

Almost no change in Δ Rmax & CW



AAAAA

15/17 Oct. 16, 2006

Δ SiO2

Δ a-SiΔ Rmax Δ SiO2 CW Δ a-Si CW

In order to prove the above relationshipsthe Δ of Rmax & CW vs. the Δ of SiO2 or a-Si was simulated

0

0 .1

0 .2

0 .3

0 .4

0 .5

0 .6

0 .7

0 .8

12 12 .5 13 13 .5 14 14 .5 15

00 .511 .522 .533 .544 .55

0

0 .1

0 .2

0 .3

0 .4

0 .5

0 .6

0 .7

0 .8

12 12 .5 13 13 .5 14 14 .5 15

1010 .51111 .51212 .51313 .51414 .515

ΔRmax & CW vs. SiO2 Thickness ΔRmax & CW vs. a-Si Thickness

As SiO2 thickness increases, ΔRmax decreases and CW increases.

As a-Si thickness increases, Δ Rmax decreases and CW decreases.



AAAAA

16/17 Oct. 16, 2006

CONCLUSIONS

• We have investigated the effects of current cleaning processes such as SPM, O3 water, plasma ashing, SC-1, and H2 water on the reflectivity of EUV mask.

• We observed that Rmax increases after cleaning processes with etching effect (e.g. SC-1) while Rmax decreases after cleaning processes with oxidation effect(e.g. O3 water or plasma ashing).

• We also observed that CW moves towards shorter wavelength after O3 water cleaning process but it moves towards longer wavelength after Ashing process.

• Simulation and ellipsometry analysis signify that the thickness increase of either SiO2 or a-Si layer causes Rmax to decrease. Since O3 water process thickens a-Si layer while ashing process thickens SiO2 layer, either process eventually reduces Rmax.

• This analysis also confirmed that the thickness increase of SiO2 layer and a-Si layer causes CW to move towards longer and shorter wavelength, respectively. O3 water process drives CW towards shorter wavelength since it thickens a-Si layer while ashing process towards longer wavelength since it thickens SiO2 layer.



AAAAA

17/17 Oct. 16, 2006

FUTURE WORK

• We will select current cleaning processes that do not affect the reflectivity of EUVmask and then combine them into a series of cleaning procedures for better PRE and less damage.

• We are also working on the development of cleaning processes that can significantly reduce chemical contamination on the EUV mask surface for the purpose of reducingany possibilities of progressive defect creation on it during laser exposure.

ACKNOWLEDGEMENT

• We would like to appreciate the help made by Kyongyoon Bang fromSamsung Electronics for the ellipsometry analysis of EUV mask.

AAAAA - euvlsymposium.lbl.goveuvlsymposium.lbl.gov/pdf/2006/posters... · AAAAA 3/17 Oct. 16, 2006...

Documents

Transcript of AAAAA - euvlsymposium.lbl.goveuvlsymposium.lbl.gov/pdf/2006/posters... · AAAAA 3/17 Oct. 16, 2006...