Characterization of small phase defects using a micro-coherent extreme ultraviolet scatterometry microscope

Tanaka, Yusuke; Harada, Tetsuo; Amano, Tsuyoshi; Usui, Youichi; Watanabe, Takeo; Kinoshita, Hiroo

doi:10.7567/jjap.53.06jc03

Cited by 11 publications

(7 citation statements)

References 33 publications

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“…9) Especially the ULSI wafer with several types of insulators such as SiO 2 , Si 3 N 4 , HfO 2 , and wafers with three-dimensionally-stacked pattern such as contact/via hole patterns lead to the difficulty for the homogenization of the surface potential. We have been developing a projection electron microscope (PEM) [7][8][9][10] for patterned photomask inspection for extreme ultraviolet (EUV) lithography; [11][12][13][14] and we have evaluated its feasibility. [15][16][17][18][19][20][21][22] PEM is one of the electron microscope techniques that is based upon the imaging EO, and has an advantage of giving a considerably higher throughput than achievable in the case of conventional scanning electron microscope (SEM) type inspection system.…”

Section: Introductionmentioning

confidence: 99%

Analysis of image distortion on projection electron microscope image

Iida¹,

Hirano²,

Terasawa³

et al. 2014

Jpn. J. Appl. Phys.

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Distortion of image obtained from a projection electron microscope (PEM) was investigated using an upgraded Monte Carlo simulation assembled with electron imaging optics (EO) data. A simulated PEM image distortion was reconstructed by the imaging on the image-plane through the EO. The image distortion was created by a local field effect (Type II). The displacement of lines, contrast degradation, and changes in the line widths were simultaneously observed. In the case of a negative charge condition, these image degradations were enhanced by an increased gradient of the electric field produced by a local charge and an extraction voltage. The image distortion and the associated image degradation were improved by applying a 7.5-times higher extraction voltage.

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Section: Introductionmentioning

confidence: 99%

Analysis of image distortion on projection electron microscope image

Iida¹,

Hirano²,

Terasawa³

et al. 2014

Jpn. J. Appl. Phys.

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“…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]. A micro-CSM [16][17][18][19] that uses a Fresnel zone plate (FZP) to focus the coherent EUV light has also been constructed for the purpose of evaluating small phase defects on a mask blank. Observation of actual phase defects on a mask blank was then demonstrated using this system [12].…”

Section: Introductionmentioning

confidence: 99%

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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“…We have developed a coherent EUV scatterometry microscope (CSM) for observing EUV patterns with a quantitative phase contrast. [12][13][14][15][16][17][18][19] The exposure light should be highly coherent. A synchrotron radiation EUV light was used as the coherent source for this CSM work.…”

Section: Introductionmentioning

confidence: 99%

Extreme ultraviolet mask observations using a coherent extreme ultraviolet scatterometry microscope with a high-harmonic-generation source

Fujino

Tanaka

Harada

et al. 2015

Jpn. J. Appl. Phys.

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In extreme ultraviolet (EUV) lithography, the three-dimensional structure of an EUV mask, which has an absorber layer and a Mo/Si multilayer on a glass substrate, strongly affects the EUV phase. We have developed a coherent EUV scatterometry microscope (CSM) to observe EUV patterns with a quantitative phase contrast based on the coherent-diffraction-imaging method, which is a simple system without an objective. A coherent stand-alone high-harmonic-generation (HHG) EUV source has been developed for practical use. Although the throughput of the relay optics in the previous study was insufficient to compensate for the fluctuation of the beam position, herein the beam position is stabilized and the relay optics are upgraded, increasing the throughput of the EUV power 130-fold. Consequently, the detection time for the same defect size is markedly reduced from 1000 to 1 s. Furthermore, a 52 ' 52 nm 2 absorber defect is detected in 10 s.

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Characterization of small phase defects using a micro-coherent extreme ultraviolet scatterometry microscope

Cited by 11 publications

References 33 publications

Analysis of image distortion on projection electron microscope image

Analysis of image distortion on projection electron microscope image

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

Extreme ultraviolet mask observations using a coherent extreme ultraviolet scatterometry microscope with a high-harmonic-generation source

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