EUV lithography scanner for sub-8nm resolution

Schoot, Jan van; Schenau, Koen van Ingen; Valentin, Chris; Migura, Sascha

doi:10.1117/12.2087502

Cited by 30 publications

(16 citation statements)

References 9 publications

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“…For experiments where higher sampling is desired, the highest magnification with 6.5 pixels per resolution element can be used. 4 Like SHARP's standard zoneplates, the 0.55 4x/8x NA zoneplates are patterned with e-beam lithography and electroplated using 35 nm of gold on a 100-nm silicon nitride membrane. The SEM-images in Fig.…”

Section: Zoneplatementioning

confidence: 99%

“…Both of these options are considered economically not viable. 4 Zeiss and ASML have proposed an anamorphic projection optic with increased mask-side NA perpendicular to the plane of incidence and increased demagnification in the plane of incidence. 5 Such a design avoids high angles of incidence on the photomask in the plane of incidence (that would degrade image quality) while preserving the demagnification perpendicular to the plane of incidence.…”

Section: Introductionmentioning

confidence: 99%

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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: Zoneplatementioning

confidence: 99%

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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show abstract

“…If the secondary electron blur is lower, the resolution might be further increased down to 5 nm HP. For high volume manufacturing (HVM), EUV scanners with 0.55 NA optics might be able to achieve 6 nm HP resolution [25]. This requires suitable photoresists with much higher sensitivity than that of HSQ.…”

Section: Discussionmentioning

confidence: 99%

Photolithography reaches 6 nm half-pitch using EUV light

Fan

Ekinci

2016

SPIE Proceedings

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EUV interference lithography records the interference pattern of two diffracted, coherent light beams, where the pattern resolution is half the diffraction grating resolution. The fabrication of diffraction grating masks by ebeam lithography is restricted by the electron proximity effect and pattern transfer limitations into diffraction efficient materials. By patterning HSQ lines at a relaxed pitch to avoid the electron proximity effect, depositing conformal iridium via atomic layer deposition, followed by ion milling the top and bottom iridium and HSQ removal, we fabricated iridium diffraction gratings at double the line spacing of the original HSQ lines. 6 nm half-pitch patterns were achieved using these masks marking a new record resolution in photolithography.

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“…Moving away from the 4x isomorphic mask towards the 4x/8x anamorphic mask has several impacts for the mask and for the lithography tool [16]. In section 6.1 the main differences for the mask will be discussed.…”

Section: The Mask: Impact and Opportunitiesmentioning

confidence: 99%

EUV high-NA scanner and mask optimization for sub-8nm resolution

Jan¹,

Koen²,

Bottiglieri³

et al. 2016

SPIE Proceedings

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EUV lithography for resolution below 8 nm half pitch requires the numerical aperture (NA) of the projection lens to be significantly larger than the current state-of-the-art 0.33NA. In order to be economically viable, a throughput in the range of 100 wafers per hour is needed.As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently the shadowing and the variation of the multi-layer reflectivity deteriorate the aerial image contrast to unacceptably low values at the current 4x magnification.The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that we have to double the magnification to 8x in order to overcome the shadowing effects. Assuming that the mask infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field size of current 0.33NA step & scan systems. This would reduce the throughput of the high-NA scanner to a value significantly below 100 wafers per hour unless additional measures are taken. This paper presents an anamorphic step & scan system capable to print fields that are half the field size of the current full field. The anamorphic system has the potential to achieve a throughput in excess of 150 wafers per hour by increasing the transmission of the optics as well as increasing the acceleration of the wafer stage and mask stage. This makes it an economically viable lithography solution.The proposed 4x/8x magnification is not the only logical solution. There are potentially other magnifications to increase the scanner performance while at the same time reducing the mask requirements.

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EUV lithography scanner for sub-8nm resolution

Cited by 30 publications

References 9 publications

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Photolithography reaches 6 nm half-pitch using EUV light

EUV high-NA scanner and mask optimization for sub-8nm resolution

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