Thermal stability of soft x-ray Mo–Si and MoSi_2-Si multilayer mirrors

Кондратенко, В. В.; Pershin, Yurii P.; Poltseva, O. V.; Fedorenko, A. I.; Zubarev, E. N.; Yulin, Sergiy; Кожевников, И. В.; Sagitov, S. I.; Чирков, В. А.; Levashov, V. E.; Виноградов, А. В.

doi:10.1364/ao.32.001811

Cited by 55 publications

(17 citation statements)

References 8 publications

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“…The first advantage is that this leads to sharp and stable interfaces, because MoSi 2 and Si are neighbors in the phase diagram of Mo-Si alloys and, thus, are close to thermodynamic equilibrium. The second advantage is a high thermal stability with invariable reflectivity up to the annealing temperature of 1000 K, instead of 600 K for conventional Mo/Si structure [19]. This is important for mirrors operating under high thermal and radiation loads.…”

Section: Fidelity Parameters and Merit Functionmentioning

confidence: 99%

Reflective aperiodic multilayer filters for metrology at XUV sources

et al. 2020

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We present a general method for designing XUV aperiodic multilayer mirrors that can mimic a given target spectrum, specifically, the spectral transmission of an XUV optical system. The method is based on minimizing a merit function and using fidelity parameters that quantify the matching of the multilayer reflectivity spectrum with that of the target spectrum. To assess the feasibility of fabricating such a system, we show how to reduce the layer-to-layer thickness variations throughout the aperiodic layer stack. We demonstrate the design method using an example of an EUV optical system composed of 12 identical Mo/Si multilayer mirrors having a reflectivity peak at 13.5 nm. We found that the target spectrum can be mimicked with high fidelity either with a single reflection at an aperiodic multilayer mirror combined with standard absorbing filters or, if required, with two subsequent reflections at a mimic mirror. These examples demonstrate the applicability for metrology at XUV sources, including spectrally proper source imaging. Because our approach is of general applicability, the process can be used to mimic any other narrowband, single-peaked target spectrum in the XUV region.

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Section: Fidelity Parameters and Merit Functionmentioning

confidence: 99%

Reflective aperiodic multilayer filters for metrology at XUV sources

et al. 2020

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“…Moreover, it is known that annealing at elevated temperatures accelerates the growth of such inter-diffusion layers further [4,5]. Consequently, interface stabilization for Mo/Si coatings has been addressed by a number of research groups in the past [6][7][8][9][10]. A promising concept is the introduction of ultra-thin diffusion barrier layers at the interfaces to inhibit layer intermixing.…”

Section: High-temperature Multilayer Developmentmentioning

confidence: 99%

Enhanced reflectivity and stability of high-temperature LPP collector mirrors

et al. 2008

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The source output power and lifetime, including the collector optics lifetime, are among the key issues for EUV lithography systems. In order to meet the requirements for the EUV collector mirror, both the reflectivity and the long-term thermal stability of its multilayer coating have been enhanced considerably during recent development efforts. Sub-aperture ellipsoidal mirrors of different substrate materials with outer diameters of about 320 mm were coated with laterally graded high-temperature multilayers. The interface-engineered Mo/Si multilayer mirror (MLM) coatings were optimized in terms of high peak reflectivity at 13.5 nm and working temperatures above 400°C. Thin barrier layers were introduced on both interfaces to block thermally induced interdiffusion processes of molybdenum and silicon and to provide long-term optical stability of the coating at elevated temperatures. A normal-incidence reflectance of R ~ 60 % at 13.5 nm was measured on Si wafer samples after heating up to 600°C. No degradation of the optical properties of these multilayer coatings occurred during both long-term heating tests and multiple annealing cycles. On highly polished collector substrates with improved surface roughness a reflectance for s-polarized light exceeding peak values of R = 57 % was obtained. With optimized layer gradient the degree of wavelength matching was improved, as well, resulting in peak reflectivity values above 56 % throughout the clear aperture for a series of measurement points across the mirror. The corresponding area-weighted 2% in-band average reflectance for this collector mirror coating exceeds 52 % for unpolarized light

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“…The optical and structural properties of a number of promising candidate high-temperature multilayer systems were studied in detail by several groups previously [3][4][5][6][7]. Based on our initial tests [8], a high-temperature multilayer coating with thin barrier layers of high inertness (X) was developed to enhance the thermal stability of the Mo/Si multilayer structure.…”

Section: High-temperature Multilayer Developmentmentioning

confidence: 99%

High-temperature LPP collector mirror

et al. 2006

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The EUV source output power and the collector optics lifetime have been identified as critical key issues for EUV lithography. In order to meet these requirements a heated collector concept was realized for the first time. An ellipsoidal collector Substrate with an outer diameter of 320 mm was coated with a laterally graded high-temperature multilayer. The interface-engineered Mo/Si multilayer coating was optimized in terms of high peak reflectivity at 13.5 nm and a working temperature of 400 °C. Barrier layers were introduced on both interfaces to block thermally induced interdiffusion processes of molybdenum and silicon to provide long-term optical stability of the multilayer at elevated temperatures. A normal-incidence reflectance of more than 40 % at 13.55 nm was measured after heating. After initial annealing at 400 °C for one hour, no degradation of the optical properties of these multilayer coatings occurred during both long-term heating tests for up to 100 hours and multiple annealing cycles. The successful realization of this high-temperature sub-aperture collector mirror represents a major step towards the implementation of the heated collector concept and illustrates the great potential of high-temperature EUV multilayer coatings

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Thermal stability of soft x-ray Mo–Si and MoSi_2-Si multilayer mirrors

Cited by 55 publications

References 8 publications

Reflective aperiodic multilayer filters for metrology at XUV sources

Reflective aperiodic multilayer filters for metrology at XUV sources

Enhanced reflectivity and stability of high-temperature LPP collector mirrors

High-temperature LPP collector mirror

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