Critical Dimension Measurement of an Extreme-Ultraviolet Mask Utilizing Coherent Extreme-Ultraviolet Scatterometry Microscope at NewSUBARU

Harada, Tetsuo; Nakasuji, Masato; Tada, Masaki; Nagata, Yutaka; Watanabe, Takeo; Kinoshita, Hiroo

doi:10.7567/jjap.50.06gb03

Cited by 11 publications

(9 citation statements)

References 7 publications

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“…The CSM was installed in the BL-3 beam line of the NewSUBARU synchrotron radiation facility, which employs a bending magnet as a light source [7,8]. Two toroidal mirrors were used to collimate and deliver the SR to a concave mirror in the CSM system.…”

Section: Csm Equipped With Srmentioning

confidence: 99%

“…However, there is no commercially available tool for the accurate determination of the precise shape of the buried defects on mask blanks or the printability of the defects in the patterned mask. Coherent scatterometry microscopy is one of the most attractive methods used to solve the aforementioned issues [7][8][9][10][11]. The coherent EUV scatterometry microscope (CSM) offers reflection mode coherent diffractive imaging (CDI) [12].…”

Section: Introductionmentioning

confidence: 99%

“…We have developed the CSM system with a SR source to establish the actinic metrology as well as inspection algorithms [7][8][9][10][11]. We then demonstrated the reconstruction of the intensity and phase images of the line-and-space patterns (L/S), the cross pattern, and the programmed phase defect [9,10].…”

Section: Introductionmentioning

confidence: 99%

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At wavelength coherent scatterometry microscope using high-order harmonics for EUV mask inspection

Nagata

Harada

Watanabe

et al. 2019

Int. J. Extrem. Manuf.

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In this review, we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet (EUV) lithography. EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors. Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips. Fabrication and inspection of defect-free masks, however, still remain critical issues in EUV technology. Thus, in our pursuit for a resolution, we have developed the coherent EUV scatterometry microscope (CSM) system with a synchrotron radiation (SR) source to establish the actinic metrology, along with inspection algorithms. The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms. To expedite the practical application of the CSM, we have also developed a standalone CSM, based on high-order harmonic generation, as an alternative to the SR-CSM. Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern, diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed. Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure, an aperiodic angle edge structure, as well as a cross pattern in an EUV mask.

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Section: Csm Equipped With Srmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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At wavelength coherent scatterometry microscope using high-order harmonics for EUV mask inspection

Nagata

Harada

Watanabe

et al. 2019

Int. J. Extrem. Manuf.

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“…Gerchberg-Saxton 13 and HIO methods have been adopted in several recent studies 1,3,5,[14][15][16][17][18][19][20] for mask inspection in EUVL. Harada et al 1,14,17 reported the development of coherent scatterometry microscope to characterize mask defect.…”

Section: Application Of Hybrid Input-output For Mask Inspectionmentioning

confidence: 99%

Accurate characterization of mask defects by combination of phase retrieval and deterministic approach

et al. 2016

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Abstract. We present a method to characterize not only shape but also depth of defects in line and space mask patterns. Features in a mask are too fine for a conventional imaging system to resolve them and a coherent imaging system providing only the pattern diffracted by the mask is used. Then phase retrieval methods may be applied, but the accuracy is too low to determine the exact shape of the defect. Deterministic methods have been proposed to accurately characterize the defect, but this requires a reference pattern. We propose to use a phase retrieval algorithm to retrieve the general shape of the mask and then apply a deterministic approach to precisely characterize the defects detected. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…Coherent scattering microscopy (CSM) is an actinic inspection and metrology tool that can obtain an aerial image of EUV masks using reverse Fourier transform of the diffraction pattern in conjunction with a phase retrieval algorithm. [11][12][13][14][15][16] Using CSM, one can obtain aerial images without requiring complex optics. One can also simulate imaging quality under various illumination conditions.…”

Section: Introductionmentioning

confidence: 99%

Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

Lee

Hong

Ahn

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors evaluated the feasibility of using coherent scattering microscopy (CSM) as an actinic metrology tool by employing it to determine the critical dimension (CD) and normalized image log-slope (NILS) values of contaminated extreme ultraviolet (EUV) masks. CSM was as effective as CD scanning electron microscopy (CD-SEM) in measuring the CD values of clean EUV masks in the case of vertical patterns (nonshadowing effect); however, only the CSM could detect shadowing effect for horizontal patterns resulting in smaller clear mask CD values. Owing to weak interaction between the low-density contaminant layer and EUV radiation, the CSM-based CD measurements were not as affected by contamination as were those made using CD-SEM. Furthermore, CSM could be used to determine the NILS values under illumination conditions corresponding to a high-volume manufacturing tool.

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Critical Dimension Measurement of an Extreme-Ultraviolet Mask Utilizing Coherent Extreme-Ultraviolet Scatterometry Microscope at NewSUBARU

Cited by 11 publications

References 7 publications

At wavelength coherent scatterometry microscope using high-order harmonics for EUV mask inspection

At wavelength coherent scatterometry microscope using high-order harmonics for EUV mask inspection

Accurate characterization of mask defects by combination of phase retrieval and deterministic approach

Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

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