Experimental measurements of telecentricity errors in high-numerical-aperture extreme ultraviolet mask images

Raghunathan, Sudharshanan; Wood, O. R.; Mangat, Pawitter J. S.; Verduijn, Erik; Philipsen, Vicky; Hendrickx, Eric; Jonckheere, R.; Goldberg, Kenneth A.; Benk, Markus P.; Kearney, Patrick A.; Levinson, Zachary A.; Smith, Bruce W.

doi:10.1116/1.4901876

Cited by 17 publications

(8 citation statements)

References 7 publications

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“…SHARP is a synchrotron-based, actinic, EUV mask microscope, located at a bending-magnet beamline at the Advanced Light Source at Lawrence Berkeley National Laboratory. Since its commissioning in 2013, SHARP has contributed to many aspects of EUV mask technology, including defects, 7 their detection 8 and printability, 9 repairs, 10 substrate roughness, 10 impact of non-telecentricity 11 and multilayer properties. 12 An overview of SHARP can be found in Ref.…”

Section: Introductionmentioning

confidence: 99%

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Benk

Wojdyla

Chao

et al. 2016

J. Micro/Nanolith. MEMS MOEMS

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Abstract. The SHARP High numerical aperture Actinic Reticle review Project is a synchrotron-based, extreme ultraviolet (EUV) microscope dedicated to photomask research. SHARP emulates the illumination and imaging conditions of current EUV lithography scanners and several generations into the future. An anamorphic imaging optic with increased mask-side numerical aperture (NA) in the horizontal and increased demagnification in the vertical direction has been proposed to overcome limitations of current multilayer coatings and extend EUV lithography beyond 0.33 NA. Zoneplate lenses with an anamorphic 4x/8x NA of 0.55 are fabricated and installed in the SHARP microscope to emulate anamorphic imaging. SHARP's Fourier synthesis illuminator with a range of angles exceeding the collected solid angle of the newly designed elliptical zoneplates can produce arbitrary angular source spectra, matched to anamorphic imaging. A target with anamorphic dense features down to 50-nm critical dimension is fabricated using 40-nm of nickel as the absorber. In a demonstration experiment anamorphic imaging at 0.55 4x/8x NA and 6º central ray angle (CRA) is compared to conventional imaging at 0.5 4x NA and 8º CRA. A significant contrast loss in horizontal features is observed in the conventional images. The anamorphic images show the same image quality in the horizontal and vertical directions.

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Section: Introductionmentioning

confidence: 99%

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Benk

Wojdyla

Chao

et al. 2016

J. Micro/Nanolith. MEMS MOEMS

Self Cite

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“…Heightened attention to mask 3D effects has been driven in large measure by their increased significance at the dimensions of future generations of technology for which EUV lithography is expected to be used. Manifestations of mask 3D effects include dependence of the planes of best focus on pitch, 20 pattern shifts coupled to focus variations, 21 and image blurring. 22 Optimization of the source and mask to mitigate these effects involves a significantly more complex computational situation than encountered in optical lithography, where OPC computation times are already approaching unacceptable levels.…”

Section: Mitigation Of Mask 3d Effectsmentioning

confidence: 99%

“…Overlay control will need to be 3.5 nm (3) and tighter. 31 Moreover, with EUV lithography there are sources of overlay error, such as mask non-flatness 32 and non-telecentricity, 21 that are not found in optical lithography, and the impact of aberrations on overlay will be greater for EUV than for optical lithography. 33 Focus control will need to be very tight for future generations of EUV lithography.…”

Section: Process Control For Euv Lithographymentioning

confidence: 99%

The potential of EUV lithography

Levinson¹

2019

35th European Mask and Lithography Conference (EMLC 2019)

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Lithographers are currently unable to generate quality patterning at tight pitches with values of k1 that are as low as have been achieved routinely using ArF immersion patterning, a situation that is largely due to the continuing pursuit of resists with low exposure doses. As a consequence, multiple patterning may be required to scale to a second node with EUV lithography, which reduces its cost-effectiveness, even if each individual exposure is done with a low exposure dose. Because of process control limitations, such multiple patterning may necessarily be triple or quadruple patterning, rather than double patterning. Processes with reduced line-edge roughness (LER) could be applied to front-end layers, increasing the value of EUV lithography. High-NA EUV lithography is in development, with a number of technical issues requiring solution, but with no apparent show-stoppers.

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“…Pattern shifts through focus have been identified as manifestations of mask 3D effects. 19 Process-window OPC will need to include shifts of the center lines of features, not just edges individually. This sensitivity to focus, particularly when there may be different planes for best focus for different features, indicates that EUV lithography will require very tight focus control.…”

Section: Computational Lithographymentioning

confidence: 99%

Current challenges and opportunities for EUV lithography

Levinson¹,

Brunner

2018

International Conference on Extreme Ultraviolet Lithography 2018

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The semiconductor industry is on the threshold of using extreme ultraviolet (EUV) lithography in high volume manufacturing (HVM). Nevertheless, there are several areas where improvement in this lithographic technology would be very beneficial, most notably exposure tool reliability (particularly the light source) and mask contamination. These areas have important consequences for productivity. Future generations of EUV lithography are expected, but there are several challenges to be overcome, particularly in the areas of resists and computational lithography. A replacement for chemically amplified resists may be required. Regardless of resist type, exposure doses must be sufficiently high to prevent photon shot noise from causing high levels of yield loss. Computational lithography for next generation EUV lithography will be very complex.

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Experimental measurements of telecentricity errors in high-numerical-aperture extreme ultraviolet mask images

Abstract: High sensitivity actinic detection of native defects on extreme ultraviolet lithography mask blanks

Cited by 17 publications

References 7 publications

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

The potential of EUV lithography

Current challenges and opportunities for EUV lithography

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