At-Wavelength Extreme Ultraviolet Lithography Mask Observation Using a High-Magnification Objective with Three Multilayer Mirrors

Toyoda, Mitsuo; Yamasoe, Kenjiro; Hatano, Tadashi; Yanagihara, Mihiro; Tokimasa, Akifumi; Harada, Tetsuo; Watanabe, Takeo; Kinoshita, Hiroo

doi:10.1143/apex.5.112501

Cited by 22 publications

(17 citation statements)

References 16 publications

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“…The fluctuations are not mask defect. 22) In a previous paper, we reported that the hp 225 and 88 nm L/S without the residual-type defects were clearly resolved with the image contrasts of 0.64 and 0.52, respectively. 22) The impacts of the residual-type defect on the EUV reflectivity were calculated from the captured images.…”

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confidence: 79%

“…17) Therefore, this study focuses on the effects of various thicknesses of the residual-type defects on printed features by employing the EUV microscope as a mask pattern inspection tool. [18][19][20][21][22] This is because in inspecting narrow mask patterns such as half-pitch (hp) 88 nm lines and spaces (L/S) it is difficult to obtain excellent image contrast and analyze the multilayer damage using an inspection tool which employs deep ultraviolet light. 5) While it is true that in atomic force microscopy (AFM) the image quality is affected by cantilever tip quality, this technique has the potential in inspecting pattern sizes as small as hp 88 nm L/S.…”

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confidence: 99%

“…The objective with its high numerical aperture of 0.25 is capable of providing a high spatial resolution near 30 nm. 22) The exposure time was set to be 100 s. Figure 1(a) shows the EUV microscopy images of hp 225 nm L/S with a residualtype defect, and Fig. 1(b) shows the light intensity profile.…”

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confidence: 99%

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Observation of Residual-Type Thin Absorber Defect on Extreme Ultraviolet Lithography Mask Using an Extreme Ultraviolet Microscope

Amano¹,

Iida²,

Hirano³

et al. 2013

Appl. Phys. Express

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A local etching technique using electron beams has been proposed to repair defects on an absorber pattern. In this paper, the effect of pattern contrast over a thin absorber film left on a multilayer was examined. Various residual absorber films on the multilayer were fabricated and examined using an extreme ultraviolet (EUV) microscope employed as an at-wavelength mask pattern inspection tool. As a result, the contrast decreased by 30% in the remaining thickness of 2.9 nm for half-pitch 225 nm features. The EUV microscope proved to be an effective tool for examining the post repair effects.

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Observation of Residual-Type Thin Absorber Defect on Extreme Ultraviolet Lithography Mask Using an Extreme Ultraviolet Microscope

Amano¹,

Iida²,

Hirano³

et al. 2013

Appl. Phys. Express

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“…These fluctuations are not mask defect. 27 However, the captured images clearly indicate the intensity loss of the EUV light from the space pattern due to the presence of the phase defects. In these cases, the locations of the phase defects were defined as 56, 88, and 160 nm in position.…”

Section: Observation Of the Phase Defects Using Euv Microscopementioning

confidence: 97%

Observation of phase defect on extreme ultraviolet mask using an extreme ultraviolet microscope

Amano¹,

Terasawa²,

Watanabe³

et al. 2014

J. Micro/Nanolith. MEMS MOEMS

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Abstract. Influences of phase defect structures on extreme ultraviolet (EUV) microscope images were examined. Phase defects on the bottom of a multilayer (ML) do not always propagate vertically upward to the ML's top surface. For this study, two types of masks were prepared. One was an EUV blank with programmed phase defects made of lines in order to analyze the inclination angle of the phase defects. The other was an EUV mask that consists of programmed dot type phase defects 80 nm wide and 2.4 nm high with absorber patterns of halfpitch 88-nm lines-and-spaces. The positions of the phase defects relative to the absorber lines were designed to be shifted accordingly. Transmission electron microscope observations revealed that the line type phase defects starting from the bottom surface of the ML propagated toward the ML's top surface, while inclined toward the center of the EUV blank. At the distances of 0 and 66 mm from the center of the EUV blank, the inclination angles varied from 0 to 4 deg. The impacts of the inclination angles on EUV microscope images were significant even though the positions of the phase defect relative to the absorber line, as measured by a scanning probe microscope, were the same. © 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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“…EUV microscopes have been long developed to observe circuit pattern images at actual exposure wavelength, that is, under EUV light . There are also microscopes that make possible observation at the same conditions as in exposure machines .…”

Section: Introductionmentioning

confidence: 99%

Development of an EUV Microscope with Focused Coherent EUV Based on Coherent Diffraction Imaging Method for Defect Evaluation on an EUV Mask

Harada

Hashimoto

Watanabe

2018

Elect Comm in Japan

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SUMMARY For evaluation of defects on extreme ultraviolet (EUV) masks at the blank state of manufacturing, we developed a microcoherent EUV scatterometry microscope (micro‐CSM). The illumination source is coherent EUV light with a 140‐nm focus diameter on the defect using a Fresnel zoneplate. This system directly observes the reflection and diffraction signals from a phase defect. The phase and the intensity image of the defect is reconstructed with the diffraction images using ptychography, which is an algorithm of the coherent diffraction imaging. We observed programmed phase defect on a blank EUV mask. Phase distributions of these programmed defects were well reconstructed quantitatively. We also observed actual defects which were inspected by the ABI tool. Actual amplitude defect and phase defect images were reconstructed with intensity and phase contrast. The reconstructed image indicated the defect type of these defect. The micro‐CSM is very powerful tool to evaluate an EUV phase defect.

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At-Wavelength Extreme Ultraviolet Lithography Mask Observation Using a High-Magnification Objective with Three Multilayer Mirrors

Cited by 22 publications

References 16 publications

Observation of Residual-Type Thin Absorber Defect on Extreme Ultraviolet Lithography Mask Using an Extreme Ultraviolet Microscope

Observation of Residual-Type Thin Absorber Defect on Extreme Ultraviolet Lithography Mask Using an Extreme Ultraviolet Microscope

Observation of phase defect on extreme ultraviolet mask using an extreme ultraviolet microscope

Development of an EUV Microscope with Focused Coherent EUV Based on Coherent Diffraction Imaging Method for Defect Evaluation on an EUV Mask

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