High-accuracy EUV reflectometry at large optical components and oblique incidence

Laubis, Christian; Scholze, Frank; Buchholz, Christian; Fischer, Andreas; Hesse, Steven; Kampe, Annett; Puls, Jana; Stadelhoff, Christian; Ulm, G.

doi:10.1117/12.813697

Cited by 9 publications

(4 citation statements)

References 14 publications

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“…The total uncertainty of each of these R values is around 0.1% with a reproducibility of 0.05%. 15 The increase of 1.5% from 13.5 to 12.56 nm and 1.1% from 13.5 to 12.7 nm is similar to what was observed in other experiments: about 1% from 13.5 to 12.7 by Bajt et al, 16 or Stuik et al 4 The obtained full experimental dependence R 0 has a trend very close to the calculated one (comparison shown in Fig. 5(A) with calculated curve scaled down), with only one notable exception-the drop of R starts at a longer 0 in experiment than in theory.…”

Section: Resultsmentioning

confidence: 99%

Angular and Spectral Bandwidth of Extreme UV Multilayers Near Spacer Material Absorption Edges

Zameshin

Yakshin

Chandrasekaran

et al. 2019

j nanosci nanotechnol

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High resolution imaging systems for EUV range are based on multilayer optics. Current generation of EUV lithography uses broadband Sn LPP sources, which requires broadband mirrors to fully utilize the source power. On the other hand, there always remains a possibility to use FEL or synchrotron as EUV source. FEL can produce very bright narrowband EUV light of a tunable wavelength, and the spectral bandwidth of the mirror is no longer a restriction. In this paper we look at the consequences of switching to different wavelengths if FEL source is used. For instance, it is known that the reflectance of Mo/Si multilayers increases when approaching Si Ledge , and the spectral bandwidth drops. But the behavior of an angular bandwidth (and its relation with the spectral bandwidth) is usually left out. It is also sometimes assumed that these bandwidths are correlated. For a large aperture EUV optical system with diffraction-limited resolution angular acceptance of a mirror is also a very important parameter. We show that the angular bandwidth of several multilayer systems (Mo/Si, Mo/Be, Ru/Si, Ru/B, La/B) actually increases close to spacer absorption edges, opposite to what occurs with the spectral bandwidth. We study this effect and show that it is caused by an interplay of changing optical constants of respective materials used in these multilayer combinations. We also provide an experimental check of the angular bandwidth of Mo/Si multilayers at 13.5 and 12.6 nm, which confirms our calculations.

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Section: Resultsmentioning

confidence: 99%

Angular and Spectral Bandwidth of Extreme UV Multilayers Near Spacer Material Absorption Edges

Zameshin

Yakshin

Chandrasekaran

et al. 2019

j nanosci nanotechnol

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“…For verification of our reflectometer, the reflectance of this mirror was already measured at Physikalisch-Technische Bundesanstalt (PTB). 5,6,[23][24][25][26][27][28][29][30] Beam size on the sample surface was 1 × 1 mm 2 at the PTB measurement.…”

Section: Collector Mirror Samplementioning

confidence: 97%

Extreme-ultraviolet collector mirror measurement using large reflectometer at NewSUBARU synchrotron facility

Iguchi

Hashimoto

Kuki

et al. 2016

Jpn. J. Appl. Phys.

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In extreme-ultraviolet (EUV) lithography, the development of high-power EUV sources is one of the critical issues. The EUV output power directly depends on the collector mirror performance. Furthermore, mirrors with large diameters are necessary to achieve high collecting performance and take sufficient distance to prevent heat and debris from a radiation point of the source. Thus collector mirror development with accurate reflectometer is important. We have developed a large reflectometer at BL-10 beamline of the NewSUBARU synchrotron facility that can be used for mirrors with diameters, thicknesses, and weights of up to 800 mm, 250 mm, and 50 kg, respectively. This reflectometer can measure reflectivity with fully s-polarized EUV light. In this study, we measured the reflectance of a 412-mm-diameter EUV collector mirror using a maximum incident angle of 36°. We obtained the peak reflectance, center wavelength and reflection bandwidth results and compared our results with Physikalisch-Technische Bundesanstalt results.

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“…The EUV beamline [8] at the MLS [9] (5.5 nm to 48 nm) with the large reflectometer [10] for samples up to collector size with adjustable spot size from 0.1 mm x 0.1 mm to 4 mm x 4 mm is complemented by the soft X-ray beamline (from below 1 nm to 25 nm) at BESSY II, optimized for low beam divergence to facilitate scatter measurements [11] and equipped with an un-lubricated instrument for measurements with arbitrarily rotated plane of reflection.…”

Section: Instrumentationmentioning

confidence: 99%

Update on EUV radiometry at PTB

Laubis

Barboutis

Buchholz

et al. 2016

Extreme Ultraviolet (EUV) Lithography VII

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The development of technology infrastructure for EUV Lithography (EUVL) still requires higher levels of technology readiness in many fields. A large number of new materials will need to be introduced. For example, development of EUV compatible pellicles to adopt an approved method from optical lithography for EUVL needs completely new thin membranes which have not been available before. To support these developments, PTB with its decades of experience [1] in EUV metrology [2] provides a wide range of actinic and non actinic measurements at in-band EUV wavelengths as well as out of band. Two dedicated, complimentary EUV beamlines [3] are available for radiometric [4,5] characterizations benefiting from small divergence or from adjustable spot size respectively. The wavelength range covered reaches from below 1 nm to 45 nm [6] for the EUV beamlines [5] to longer wavelengths if in addition the VUV beamline is employed. The standard spot size is 1 mm by 1 mm with an option to go as low as 0.1 mm to 0.1 mm. A separate beamline offers an exposure setup. Exposure power levels of 20 W/cm 2 have been employed in the past, lower fluencies are available by attenuation or out of focus exposure. Owing to a differential pumping stage, the sample can be held under defined gas conditions during exposure. We present an updated overview on our instrumentation and analysis capabilities for EUV metrology and provide data for illustration.

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High-accuracy EUV reflectometry at large optical components and oblique incidence

Cited by 9 publications

References 14 publications

Angular and Spectral Bandwidth of Extreme UV Multilayers Near Spacer Material Absorption Edges

Angular and Spectral Bandwidth of Extreme UV Multilayers Near Spacer Material Absorption Edges

Extreme-ultraviolet collector mirror measurement using large reflectometer at NewSUBARU synchrotron facility

Update on EUV radiometry at PTB

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