Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Benk, Markus P.; Wojdyla, Antoine; Chao, Weilun; Salmassi, Farhad; Oh, Sharon; Wang, Yow-Gwo; Miyakawa, Ryan; Naulleau, Patrick; Goldberg, Kenneth A.

doi:10.1117/1.jmm.15.3.033501

Cited by 7 publications

(3 citation statements)

References 15 publications

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“…Both the pure 8× and the anamorphic system can completely recover these losses. Such behavior was recently confirmed by experiments on the SHARP microscope [50].…”

Section: Larger Na Systems For Euvsupporting

confidence: 52%

Characterization and mitigation of 3D mask effects in extreme ultraviolet lithography

Erdmann

Evanschitzky

et al. 2017

Advanced Optical Technologies

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Abstract:The reflection and diffraction of extreme ultraviolet (EUV) light from lithographic masks and the projection imaging of these masks by all-reflective systems introduce several significant imaging artifacts. The off-axis illumination of the mask causes asymmetric shadowing, a size bias between features with different orientations and telecentricity errors. The image contrast varies with the feature orientation and can easily drop far below intuitively expected values. The deformation of the wavefront or phase of the incident light by thick absorbers generates aberration-like effects, especially variations of the best-focus (BF) position vs. the pitch and size of the imaged patterns. Partial reflection of light from the top of the absorber generates a weak secondary image, which superposes with the main image. Based on a discussion of the root causes of these phenomena, we employ mask diffraction and imaging analysis for a quantitative analysis of these effects for standard EUV masks. Simulations for various non-standard types of mask stacks (e.g. etched multilayers, buried shifters, etc.) and for various non-standard absorber materials are used to explore the imaging capabilities of alternative masks for EUV lithography. Finally, an outlook at anamorphic systems for larger numerical apertures is given.

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“…Both the pure 8× and the anamorphic system can completely recover these losses. Such behavior was recently confirmed by experiments on the SHARP microscope [50].…”

Section: Larger Na Systems For Euvsupporting

confidence: 52%

Characterization and mitigation of 3D mask effects in extreme ultraviolet lithography

Erdmann

Evanschitzky

et al. 2017

Advanced Optical Technologies

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“…This includes zoneplates matching the mask side NA of the NXE:3300 scanner 3 and zoneplates for to emulation of high-NA anamorphic imaging. 4,5 The illuminator 6 in SHARP synthesizes arbitrary source-angular spectra and readily emulates the illumination conditions in EUV scanners, including freeform SMO sources. Figure 1 illustrates the light path in the instrument.…”

Section: Introductionmentioning

confidence: 99%

Upgrade to the SHARP EUV mask microscope

Benk

Chao

Miyakawa

et al. 2019

Extreme Ultraviolet (EUV) Lithography X

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The Sharp High-NA Actinic Reticle review Project (SHARP) is a synchrotron-based, extreme ultraviolet (EUV) microscope dedicated to photomask research. A potential upgrade to the SHARP microscope is presented. The upgrade includes changing the light path in the instrument from its current off-axis configuration to an on-axis configuration. This change allows for an increased working distance of 2.5 mm or more. A central obscuration, added to the zoneplate aperture, blocks stray light from reaching the central part of the image, thus improving the image contrast. The imaging performance of the two configurations is evaluated by means of ray tracing.

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A desktop extreme ultraviolet microscope based on a compact laser-plasma light source

et al. 2016

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research, such as mask inspection [6,7]-reaching 22-nm half pitch resolution or lithography [8], as well as free electron lasers [9] for coherent diffraction imaging (CDI) schemes [10]. These facilities, although state of the art and dedicated to cutting-edge science experiments, are not "user friendly," with limited user access and require high maintenance costs, because of their scale and complexity. Another approach is to use tabletop high-order harmonic (HHG) sources [11] for sub-100-nm spatial resolution imaging [12]; however, typical 10 −6 -10 −5 HHG conversion efficiency is very low and often does not allow for a proper reconstruction [13], the system is very complicated, and typical CDI requires time-consuming numerical data processing. Ptychographic schemes, although providing very high spatial resolution, are serial in nature, extensively time-consuming and computationally demanding.To partially overcome these limitations, other compact EUV sources, such as discharge [14], Z-pinch [15] or laserproduced plasma sources [16], coupled to zone plates or Schwarzschild mirrors, were used. The first one is compact and shows very good spatial resolution, but requires often (~30 k pulses) capillary replacements, the second one demonstrates quite low performance in terms of spatial resolution and field of view exploiting inadequate mode of imaging for lithographic mask inspection, while the last one requires debris mitigation schemes.The use of compact, short-wavelength sources often does not allow for high signal-to-noise ratio image acquisition. An example of that are recent developments in soft X-ray (SXR) microscopy in so-called water window, such as a compact soft X-ray microscope based on a single nitrogen gas jet, capable of resolving features ~100 nm later improved to ~50 nm in size providing high spatial resolution; however, the exposure time for Siemens star test pattern was equal to 1-2 h, limiting the usability of Abstract A compact, desktop size microscope, based on laser-plasma source and equipped with reflective condenser and diffractive Fresnel zone plate objective, operating in the extreme ultraviolet (EUV) region at the wavelength of 13.8 nm, was developed. The microscope is capable of capturing magnified images of objects with 95-nm full-pitch spatial resolution (48 nm 25-75% KE) and exposure time as low as a few seconds, combining reasonable acquisition conditions with stand-alone desktop footprint. Such EUV microscope can be regarded as a complementary imaging tool to already existing, well-established ones. Details about the microscope, characterization, resolution estimation and real sample images are presented and discussed.

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Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

Cited by 7 publications

References 15 publications

Characterization and mitigation of 3D mask effects in extreme ultraviolet lithography

Characterization and mitigation of 3D mask effects in extreme ultraviolet lithography

Upgrade to the SHARP EUV mask microscope

A desktop extreme ultraviolet microscope based on a compact laser-plasma light source

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