Electro-optical system for scanning microscopy of extreme ultraviolet masks with a high harmonic generation source

Naulleau, Patrick; Anderson, Christopher N.; Anderson, Erik H.; Andreson, Nord; Chao, Weilun; Choi, Chang-Hoon; Goldberg, Kenneth A.; Gullikson, Eric M.; Kim, Seong-Sue; Lee, Donggun; Miyakawa, Ryan; Park, Jongju; Rekawa, Senajith; Salmassi, Farhad

doi:10.1364/oe.22.020144

Cited by 8 publications

(7 citation statements)

References 20 publications

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“…While zone plate based microscopes [30,31] can achieve E10-25 nm spatial resolution using shorter wavelength light, they result in amplitude-only images and thus contain less information about the object. Compared with AFM, where image contrast comes solely from height differences regardless of material properties, CDI derives its contrast from the reflected complex exit surface wave, which includes material dependent information.…”

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confidence: 99%

High contrast 3D imaging of surfaces near the wavelength limit using tabletop EUV ptychography

et al. 2015

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Scanning electron microscopy and atomic force microscopy are well-established techniques for imaging surfaces with nanometer resolution. Here we demonstrate a complementary and powerful approach based on tabletop extreme-ultraviolet ptychography that enables quantitative full field imaging with higher contrast than other techniques, and with compositional and topographical information. Using a high numerical aperture reflection-mode microscope illuminated by a tabletop 30 nm high harmonic source, we retrieve high quality, high contrast, full field images with 40 nm by 80 nm lateral resolution (≈1.3 λ), with a total exposure time of less than 1 min. Finally, quantitative phase information enables surface profilometry with ultra-high, 6 Å axial resolution. In the future, this work will enable dynamic imaging of functioning nanosystems with unprecedented combined spatial (<10 nm) and temporal (<10 fs) resolution, in thick opaque samples, with elemental, chemical and magnetic sensitivity.

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confidence: 99%

High contrast 3D imaging of surfaces near the wavelength limit using tabletop EUV ptychography

et al. 2015

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“…Moreover, a user-defined tolerance setting in the fracturing algorithm keeps the flexibility in the computation time and the precision of the zoneplate pattern. 16 The algorithm has been used to generate Fresnel zoneplates used by the EUV mask microscope [6] at Lawrence Berkeley National Laboratory for standard imaging and other exotic imaging modes as well as tilted zoneplates for use in a scanning EUV microscope [13]. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The zoom-in views in Fig. 11c show the displacement between the patterns to introduce the 90°phase shifts as well as the apodization produced by adding blocks to the desired area on the zoneplate to control the amount of light 13 passing through each zone. The phase shift and intensity transmission are indicated in the figure for each zoneplate.…”

Section: Fresnel Zoneplate Pattern Fabrication Demonstrationmentioning

confidence: 99%

“…In addition to working for systems where the zoneplate is orthogonal to the chief ray, our algorithm also supports tilted zoneplates to deal with the tilted geometry systems often useful for reflection imaging [13]. Figure 13 shows an example of such a zoneplate designed to work with the chief ray at 6°relative to the zoneplate surface normal.…”

Section: Fresnel Zoneplate Pattern Fabrication Demonstrationmentioning

confidence: 99%

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Efficient Fresnel zoneplate pattern data preparation for high-resolution nanofabrication

Wang

Miyakawa

Chao

et al. 2017

Optics Communications

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Abstract.A Fresnel zoneplate is a diffractive optical element consisting of concentric rings (zones) for which the transmitted light produces a focal spot that is used in all wavelength regimes, including x-rays. The pattern of transmission openings determines the location of the spot and the sub-half wavelength size of the openings can adjust the intensity. Today, very general transmission zoneplate patterns are used for many special imaging and image compensation purposes. Manufacturing zoneplates require a zoneplate pattern file, which precisely describes the size, shape, and contour of the rings based on the desired optical properties of the lens. Generating such a pattern requires the delicate balance of achieving the required optical performance while maintaining manageable file sizes and computation times. Here we describe a new algorithm meeting these needs. By precisely controlling the number of shapes in each zone, the algorithm simultaneously optimizes the desired optical tolerances with the pattern file size.

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“…For mask metrology, where a limited number of defects need to be reviewed, HHG EUV sources might be considered because of their high brightness, but for inspection of the entire mask, their power is not sufficient. [19][20][21]…”

Section: Scaling Laws For Required Source Radiance and Powermentioning

confidence: 99%

Source performance metrics for EUV mask inspection

Juschkin¹,

Wack²

2022

J. Micro/Nanopattern. Mats. Metro.

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Rules are derived to obtain specifications on radiance, power, lifetime, and cleanliness of the source for an actinic patterned mask inspection system. We focus on the physical processes and technological aspects governing the requirements of radiation sources for reticle inspection. We discuss differences and similarities to scanner with respect to magnification, system etendue, and image recording. Source radiance requirements are estimated from a perspective of targeted throughput and defect detection sensitivity. The derivations consider the influence of photon shot noise on signal detection and conservation laws of light etendue and radiant flux. We describe the scaling laws for required radiance with targeted sensitivity index, optical contrast, field size, and system throughput. In addition, we address the limits on the required brightness and minimum repetition rate set by mask damage threshold. Finally, system and source cleanliness requirements and criticality of the source availability and lifetime are discussed. The analysis can be applied to other microscopy-based metrology and inspection applications.

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Electro-optical system for scanning microscopy of extreme ultraviolet masks with a high harmonic generation source

Cited by 8 publications

References 20 publications

High contrast 3D imaging of surfaces near the wavelength limit using tabletop EUV ptychography

High contrast 3D imaging of surfaces near the wavelength limit using tabletop EUV ptychography

Efficient Fresnel zoneplate pattern data preparation for high-resolution nanofabrication

Source performance metrics for EUV mask inspection

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