Mask Metrology and Pattern Profile Analysis Using the AIT: Down to 65 nm

I. Mochi, K. A. GoldbergLawrence Berkeley National Laboratory

Tom WallowGlobalFoundries

2010 International Workshop on EUV Lithography

The SEMATECH Berkeley Actinic Inspection Tool

λ = 13.2 – 13.6 nm

NA :0.0875 (0.35 4x)0.0750 (0.30 4x)0.0625 (0.25 4x)

Magnification : 907x

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

Through focus image series95 nm HP – 0.0875 NA

-2.8 µm -2.4 -2.0 -1.6 -1.2

-0.8 -0.4 0.0 0.4 0.8

1.2 1.6 2.0 2.4 2.8

1.2

µm

(24 nm HP – 0.35 NA)

Contrast through focus

The AIT currently resolves dense line patterns > 65 nm

100 nm(25 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

95 nm(24 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

90 nm (23 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

85 nm(21 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

80 nm(20 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

75 nm(19 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

70 nm(18 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

The AIT currently resolves dense line patterns > 65 nm

65 nm(16 nm)

GlobalFoundriesMask MET10

300 nm

I 1

0.5

0

Critical Dimension (wafer units) [nm]

Contrast vs. CD (CTF)

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

0.3

µm

Goldberg, JVST B 27(6) 2009

±10%

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

95 nm HP – 0.0875 NA1.

2 µm

0.3

µm

Photon flux requirements for EUV reticle imaging microscopy in the 22- and 16nm nodesDaniel T. Wintz, Kenneth A. Goldberg, Iacopo Mochi, and Sungmin Huh, Proc. SPIE 7636, 76362L (2010)

How many photons do we need?

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

1µm

1µm 1µm

1µm 1µm

EUV Defect imaging with the AIT

Actinic imaging of native and programmed defectson a full-field maskI. Mochi, K. A. Goldberg, B. La Fontaine, A. Tchikoulaeva, C. Holfeldt,

Proc. SPIE 7636 76371A, (2010)

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

Normal: No OPC

500 nm

Full OPC

500 nm

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

AIT: Tunable λ measurements from 13.2–13.6 nm

λ/Δλ=1/1450

AITbandwidth

• Narrow-band illumination is required for zoneplates.• The AIT can operate across a range of wavelengths

to synthesize broad-spectrum EUV illumination. Huh, SEMATECH

Native phase defects show little λ dependence

1.5

0.0

I

Def

ect V

Def

ect X

Def

ect 1

Def

ect 2

λ = 13.2 13.3 13.4 13.5 13.6 nm

Huh, SEMATECH

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

Phase “scratch”

π/2

0±π

-π/2

-0.57

0.66

Phase scale (rad)

0.5 µm

LensMask Through focus images

AIT measurement layout

LensMask

In focus Out of focus

AIT measurement layout

Phase Retrieval from Defocused Images and Its Applications in LithographyRudolf M. von Bunau, Hiroshi Fukuda and Tsuneo TerasawaJpn. J. Appl. Phys. 36 (1997) 7494

A practical algorithm for the determination of the phase from image and diffraction plane picturesR. W. Gerchberg and W. O. SaxtonOptik 35, 237 (1972)

?Initial phase guess

Measured amplitudes(known)

Reconstructed phase

LensMask

G-S modified algorithm

P

In focus Out of focus

PSM: A 500 nm contact (a square pillar)

0.5 µm0.5 µm

In focus Out of focus

PSM: A 150 nm contact array (a pillar grid)

0.5 µm

In focus Out of focus

0.5 µm

A real phase defect on a patterned mask

In focus Out of focus

A real phase defect on a blank mask: a “bump”

0.5 µm

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

π/2

-π/2

0

0.39

-0.36

Phase roughness on a blank mask

π/2

-π/2

0±π

Reconstructed phase

0.5 µm

In focus image

Single surface approximation height

0.8 nm (pv)0.14 nm (rms)

Conclusion

This work was supported by SEMATECH, through the U.S. Department of Energy under Contract No. DE-AC02-05CH11231

Phase roughness

BossungNILSContrast

λsensitivity

Phase defects

LER Defect inspection

OPC Correction

Acknowledgements

Kenji Yamazoe – CanonAndy Neureuther, Chris Clifford – UC BerkeleySungmin Huh – SamsungSimi George, Patrick Naulleau – LBNL

AIT.lbl.gov