Repairing native defects on EUV mask blanks

Lawliss, Mark; Gallagher, Emily; Hibbs, M.; Seki, Kazunori; Isogawa, Takeshi; Robinson, Tod; LeClaire, Jeff

doi:10.1117/12.2069787

Cited by 9 publications

(5 citation statements)

References 6 publications

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“…For defect repair the absorber material must be able to form volatile compounds by electron beam-induced chemical reaction [41]. Alternatively, nanomachining repair can remove non-volatile materials, but is less selective [42]. The absorber must remain stable under cleaning conditions, preferably basic solution to prevent the Ru capping layer from oxidizing and peeling [25].…”

Section: Film Morphologymentioning

confidence: 99%

Ni-Al Alloys as Alternative EUV Mask Absorber

et al. 2018

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Extreme ultraviolet (EUV) lithography is being industrialized as the next candidate printing technique for high-volume manufacturing of scaled down integrated circuits. At mask level, the combination of EUV light at oblique incidence, absorber thickness, and non-uniform mirror reflectance through incidence angle, creates photomask-induced imaging aberrations, known as mask 3D (M3D) effects. A possible mitigation for the M3D effects in the EUV binary intensity mask (BIM), is to use mask absorber materials with high extinction coefficient κ and refractive coefficient n close to unity. We propose nickel aluminide alloys as a candidate BIM absorber material, and characterize them versus a set of specifications that a novel EUV mask absorber must meet. The nickel aluminide samples have reduced crystallinity as compared to metallic nickel, and form a passivating surface oxide layer in neutral solutions. Composition and density profile are investigated to estimate the optical constants, which are then validated with EUV reflectometry. An oxidation-induced Al L2 absorption edge shift is observed, which significantly impacts the value of n at 13.5 nm wavelength and moves it closer to unity. The measured optical constants are incorporated in an accurate mask model for rigorous simulations. The M3D imaging impact of the nickel aluminide alloy mask absorbers, which predict significant M3D reduction in comparison to reference absorber materials. In this paper, we present an extensive experimental methodology flow to evaluate candidate mask absorber materials.

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Section: Film Morphologymentioning

confidence: 99%

Ni-Al Alloys as Alternative EUV Mask Absorber

et al. 2018

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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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“…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, 6 their detection 7 and printability, 8 repairs, 8 substrate roughness, 9 impact of non-telecentricity 10 or multilayer properties. 11 For an overview of SHARP, see Ref 12. SHARP is designed to emulate imaging in EUV scanners.…”

Section: Nmmentioning

confidence: 99%

Emulation of anamorphic imaging on the SHARP EUV mask microscope

Benk

Wojdyla

Chao

et al. 2016

Extreme Ultraviolet (EUV) Lithography VII

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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-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. 1 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/8xNA and 6º central ray angle is compared to conventional imaging at 0.5 4xNA and 8º central ray angle. 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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Repairing native defects on EUV mask blanks

Cited by 9 publications

References 6 publications

Ni-Al Alloys as Alternative EUV Mask Absorber

Ni-Al Alloys as Alternative EUV Mask Absorber

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Emulation of anamorphic imaging on the SHARP EUV mask microscope

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