Ultra-high Resolution Optics for EUV and Soft X-ray Inelastic Scattering

Voronov, Dmitriy L.; Cambie, Rossana; Ahn, Minseung; Anderson, Erik H.; Chang, Chih‐Hao; Gullikson, Eric M.; Heilmann, Ralf K.; Salmassi, Farhad; Schattenburg, Mark L.; Yashchuk, Valeriy V.; Padmore, Howard; Garrett, R. F.; Gentle, Ian R.; Nugent, Keith A.; Wilkins, S.

doi:10.1063/1.3463360

Cited by 5 publications

(5 citation statements)

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“…The main technological challenges are fabrication of nano-period saw-tooth substrates with a perfect groove profile and an atomically smooth surface of blazed facets, and deposition of a multilayer (ML) on the highly corrugated surface of the substrates. Recent progress in fabrication of saw-tooth gratings with anisotropic etching of silicon single crystals [4,5] provided the necessary quality of the substrates [6]. The main remaining problem however is coherent replication of this structure from the substrate throughout the whole multilayer stack.…”

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confidence: 99%

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Ultra-high efficiency multilayer blazed gratings through deposition kinetic control

et al. 2012

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Diffraction efficiency of multilayer coated blazed gratings (MBG) strongly depends on the perfection of the saw-toothshaped layers in the overall composite structure. Growth of multilayers on saw-tooth substrates should be carefully optimized in order to reduce groove profile distortion and at the same time to avoid significant roughening of multilayer interfaces. In this work we report on a new way to optimize growth of sputter-deposited Mo/Si multilayers on saw-tooth substrates through variation of the sputtering gas pressure. A new record for diffraction efficiency of 44% was achieved for a optimized MBG with groove density of 5250 lines/mm at the wavelength of 13.1 nm. © 2010 Optical Society of America OSIS codes: 050.1950, 120.6660, 340.7480, 230.4170, 310.1860 High efficiency diffraction gratings with high groove density are of great importance for a wide range of extreme ultraviolet (EUV) and soft x-ray applications including EUV lithography [1], astrophysics and solar science [2], and high-resolution Resonance Inelastic X-ray Scattering [3]. Multilayer-coated Blazed Gratings (MBG) can offer vastly improved performance over conventional single layer-coated gratings provided that the grating fabrication process can ensure coherent addition of each layer in the multilayer stack. The main technological challenges are fabrication of nano-period saw-tooth substrates with a perfect groove profile and an atomically smooth surface of blazed facets, and deposition of a multilayer (ML) on the highly corrugated surface of the substrates. Recent progress in fabrication of saw-tooth gratings with anisotropic etching of silicon single crystals [4,5] provided the necessary quality of the substrates [6]. The main remaining problem however is coherent replication of this structure from the substrate throughout the whole multilayer stack.Simulation of the diffraction efficiency shows that smoothening of the saw-tooth substrate by a ML deposited on it is a main limiting factor for MBG performance. Traditional deposition techniques optimized for growth of the MLs on flat substrates aim to provide interfaces of a ML stack as smooth as possible via promotion of surface relaxation processes. However, this approach does not work well for the highly corrugated surface of saw-tooth substrates, because a triangular shaped groove suffers greatly from excessive diffusion mobility of deposited atoms, caused in particular by bombardment of growing surface with energetic particles. The mobility provides effective smoothening of random roughness of interfaces, but in the same manner affects the high-frequency harmonics of a Fourier spectrum of a saw-tooth surface, causing degradation of the initial groove profile in the course the ML deposition [7,8]. As a result of this, a MBG loses its blazing ability and diffraction efficiency can be substantially reduced compared to the theoretical maximum.To avoid groove degradation one should reduce the adatom mobility. However, too low a surface mobility would result in rough interfaces and incre...

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“…Anisotropic etching of the silicon followed by isotropic chemical etch was used to produce triangular grooves in the saw-tooth substrates with the blaze angle of 2º. The details of the etch process can be found elsewhere [6].…”

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Ultra-high efficiency multilayer blazed gratings through deposition kinetic control

et al. 2012

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“…Evolution of the Mo/Si stack structure during the ML growth onto the 200 nm saw-tooth substrate were discussed earlier [9].…”

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confidence: 99%

“…Fabrication of the grating #1 with the period of 200 nm used scanning beam interference lithography [7], and the 100 nm period pattern for the grating #2 was produced with e-beam lithography. The micro-fabrication process described earlier [8] was applied to the wafers to form a saw-tooth profile of the substrates.…”

Section: Methodsmentioning

confidence: 99%

Fabrication and characterization of ultra-high resolution multilayer-coated blazed gratings

Voronov

Anderson

Cambie

et al. 2011

Nuclear Instruments and Methods in Physics Research Section A:

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Multilayer coated blazed gratings with high groove density are the most promising candidate for ultra-high resolution soft x-ray spectroscopy. They combine the ability of blazed gratings to concentrate almost all diffraction energy in a desired high diffraction order with high reflectance soft x-ray multilayers. However in order to realize this potential, the grating fabrication process should provide a near perfect groove profile with an extremely smooth surface of the blazed facets. Here we report on successful fabrication and testing of ultra-dense saw-tooth substrates with 5,000 and 10,000 lines/mm.

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“…Ранее подобное исследование никем не проводилось, а допустимое значение среднеквадратичного отклонения (СКО) шероховатости отражающей поверхности σ , как правило, оценивалось как σ ≪ λ/6 cos θ [4], где λдлина волны падающего излучения, θ -угол падения, отсчитанный от нормали. Для применений в ЭУФ считается приемлемым σ поверхности решетки ∼ 0.5−1 nm [5], a для МР диапазона ∼ 0.3−0.4 nm [6]. Исследование влияния формы профиля штрихов и шероховатости поверхности отражающей грани на отток дифракционной эффективности из рабочего порядка проводилось для Si-решеток с углом блеска 1−4…”

Section: Introductionunclassified

Кремниевые Решетки С Блеском Для Мягкого Рентгеновского И Экстремального Ультрафиолетового Излучения: Влияние Формы Профиля Штриха И Случайной Шероховатости На Дифракционную Эффективность

Горай,

Шаров,

Мохов

et al. 2023

Журнал Технической Физики

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The effect of the groove profile shape and random roughness of the reflecting facet of five silicon diffraction gratings (1°-4° blaze angle, period 0.4, 1.4, 2, and 4 μm, various coatings) operating in the soft X-ray and extreme ultraviolet radiation ranges on the outflow of the diffraction efficiency from working orders is studied. Diffraction gratings were fabricated by wet etching of Si(111) vicinal wafers and characterized by atomic force microscopy to determine the shape of the groove profile and roughness. The diffraction efficiency of gratings operating in classical and conical diffraction mounts was calculated based on realistic groove profiles by computer simulation using the PCGrateTM code and taking into account the scattering intensity using Nevot-Croce or Debye-Waller corrections or using the Monte Carlo method (rigorously). The effect of the groove profile shape and roughness on the diffraction efficiency of the fabricated Si gratings is shown.

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Ultra-high Resolution Optics for EUV and Soft X-ray Inelastic Scattering

Cited by 5 publications

References 18 publications

Ultra-high efficiency multilayer blazed gratings through deposition kinetic control

Ultra-high efficiency multilayer blazed gratings through deposition kinetic control

Fabrication and characterization of ultra-high resolution multilayer-coated blazed gratings

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