Boundary Structure of Mo/Si Multilayers for Soft X-Ray Mirrors

Ishino, Masahiko; Yoda, Osamu; Haishi, Y.; Arimoto, Fumiko; Takeda, Mitsuhiro; Watanabe, Seiichi; Ohnuki, S.; Abe, Hiroaki

doi:10.1143/jjap.41.3052

Cited by 10 publications

(7 citation statements)

References 4 publications

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“…From the test results of the two mode scans, the crystalline intensity of the samples deposited with and without the shadow mask is basically the same. The test curves of the θ-2θ mode scan were fitted by Jade software (PDF#42-1120), and it was found that the peak mainly correspond to Mo (110) crystallites in both samples, which was also found in other studies [ 33 , 34 ]. Based on the width of the Mo (110) diffraction peak, the crystallite size of Mo was calculated using Scherrer’s formula [ 35 ],

where λ = 0.1542 nm, L is the full width at half maximum determined for every peak in the spectrum and θ is the Bragg diffraction angle.…”

Section: Resultssupporting

confidence: 71%

Comparative Study on Microstructure of Mo/Si Multilayers Deposited on Large Curved Mirror with and without the Shadow Mask

et al. 2023

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The Mo/Si multilayer mirror has been widely used in EUV astronomy, lithography, microscopy and other fields because of its high reflectivity at the wavelength around 13.5 nm. During the fabrication of Mo/Si multilayers on large, curved mirrors, shadow mask was a common method to precisely control the period thickness distribution. To investigate the effect of shadow mask on the microstructure of Mo/Si multilayers, we deposited a set of Mo/Si multilayers with and without the shadow mask on a curved substrate with aperture of 200 mm by direct current (DC) magnetron sputtering in this work. Grazing incidence X-ray reflectivity (GIXR), diffuse scattering, atomic force microscope (AFM) and X-ray diffraction (XRD) were used to characterize the multilayer structure and the EUV reflectivity were measured at the National Synchrotron Radiation Laboratory (NSRL) in China. By comparing the results, we found that the layer microstructure including interface width, surface roughness, layer crystallization and the reflectivity were barely affected by the mask and a high accuracy of the layer thickness gradient can be achieved.

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where λ = 0.1542 nm, L is the full width at half maximum determined for every peak in the spectrum and θ is the Bragg diffraction angle.…”

Section: Resultssupporting

confidence: 71%

Comparative Study on Microstructure of Mo/Si Multilayers Deposited on Large Curved Mirror with and without the Shadow Mask

et al. 2023

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“…[24][25][26][27][28] We used MoSi 2 as the interdiffusion material. The densities of the Mo, Si, and MoSi 2 layers were the same for each crystal.…”

Section: Measuring the Layer Thickness Using Xrrmentioning

confidence: 99%

“…The analysis model used for the XRR spectra had four layers in one periodic Mo/Si stack with interdiffusion layers between the Mo and Si or between the Si and Mo interfaces in each of the 40 stacks with one Ru-cap capping layer on the substrate. [24][25][26][27][28] We used MoSi 2 as the interdiffusion material. The densities of the Mo, Si, and MoSi 2 layers were the same for each crystal.…”

Section: Measuring the Layer Thickness Using Xrrmentioning

confidence: 99%

Evaluating the Optical Index of Ta and Ta-Based Absorbers for an Extreme Ultraviolet Mask Using Extreme Ultraviolet Reflectometry

Hosoya¹,

Sakaya²,

Nozawa³

et al. 2008

jjap

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We developed an accurate method for determining the optical index of Ta and Ta-based absorber layers with added nitrogen, oxygen, and boron for an extreme ultraviolet (EUV) mask using EUV reflectometry. The optical index at EUV wavelengths was derived from the density and atomic concentration of the composite materials. The atomic concentrations of Ta and Ta-based absorbers were determined using X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) analysis methods when no inconsistency occurred between the results of the XPS and RBS analyses. The volume densities of the Ta and Ta-based absorbers were determined using RBS and EUV reflectivity measurements with the grazing angle (EUVRG) or reflectivity (EUVR) when no inconsistency was observed between results. Deriving the volume density was necessary to establish the layer structure and layer thickness, and the surface oxidation layer was especially important for determining the correct volume density. The layer structure and thickness were derived using a pattern-fitting method for the XRR spectrum. The extinction coefficients of Ta and Ta-based absorbers stacked using conventional sputtering were lower than the extinction coefficient of an ideal Ta crystal.

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“…These grains of Mo induced the surface roughness of the multilayer film. 7,23,25,26) The surface roughness of the substrate extends to the upper layers during deposition and contributes to the roughness of the multilayer film. The smooth surfaces of the SSQz and Si substrates have little effect; for these substrates, the grains of Mo are the main cause of the multilayer film roughness.…”

Section: Measuring Surface Roughness Using Afmmentioning

confidence: 99%

Direct Evaluation of Surface Roughness of Substrate and Interfacial Roughness in Molybdenum/Silicon Multilayers Using Extreme Ultraviolet Reflectometer

Hosoya¹,

Sakaya²,

Nozawa³

et al. 2007

jjap

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In this study, we developed a method of measuring the intensity of rays scattered from a molybdenum/silicon (Mo/Si) multilayer film using an extreme ultraviolet (EUV) reflectometer. We examined the correlations between the peak reflectance, the interfacial roughness of multilayer films, and the substrate roughness. We measured the intensity of scattered rays 13.5 nm from the substrate surface for normal smooth quartz (NSQz), supersmooth quartz (SSQz), and Si substrates using the EUV reflectometer. The intensity of rays scattered from the substrate surface was proportional to the atomic force microscopy (AFM) roughness of the surface. For NSQz, there was a particular strong correlation between the surface roughness determined by AFM and the intensity of scattering rays determined using the EUV reflectometer. However, a week correlation was observed for SSQz and Si. The precisions of the AFM and X-ray reflectivity (XRR) measurement were low for the quartz substrate. A direct measurement of the intensity of rays scattered from the substrate surface was used to estimate the relative surface roughness independent of the substrate material. The EUV reflectivity and intensity of rays scattered from the Mo/Si multilayer films with two deposition geometries were measured using the EUV reflectometer. The peak reflectivity was related to the substrate roughness for each deposition geometry. Moreover, the peak reflectivity was related to the intensity of rays scattered from the multilayer films and was not influenced by the deposition geometry. The results obtained using the EUV reflectometer showed an obvious relationship between the intensity of scattering rays and the interfacial roughness of multilayer films.

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Boundary Structure of Mo/Si Multilayers for Soft X-Ray Mirrors

Cited by 10 publications

References 4 publications

Comparative Study on Microstructure of Mo/Si Multilayers Deposited on Large Curved Mirror with and without the Shadow Mask

Comparative Study on Microstructure of Mo/Si Multilayers Deposited on Large Curved Mirror with and without the Shadow Mask

Evaluating the Optical Index of Ta and Ta-Based Absorbers for an Extreme Ultraviolet Mask Using Extreme Ultraviolet Reflectometry

Direct Evaluation of Surface Roughness of Substrate and Interfacial Roughness in Molybdenum/Silicon Multilayers Using Extreme Ultraviolet Reflectometer

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