Effect of working gas pressure on interlayer mixing in magnetron-deposited Mo/Si multilayers

Pershyn, Y. P.; Gullikson, Eric M.; Кондратенко, В. В.; Mamon, V.V.; Reutskaya, Svetlana A.; Voronov, Dmitriy L.; Zubarev, E. N.; Artyukov, I. A.; Виноградов, А. В.

doi:10.1117/1.oe.52.9.095104

Cited by 10 publications

(3 citation statements)

References 59 publications

(82 reference statements)

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“…In addition to the intermixing, the interface roughness is another factor crucial for reflectivity. It was shown that adjusting the pressure in the deposition step can significantly reduce the interface roughness in Mo/Si PMMs [45]. In addition, the roughness is also affected by the thickness of individual layers [46].…”

Section: Structural and Optical Propertiesmentioning

confidence: 99%

Multilayer Reflective Coatings for BEUV Lithography: A Review

Uzoma

Salman

et al. 2021

Nanomaterials

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The development of microelectronics is always driven by reducing transistor size and increasing integration, from the initial micron-scale to the current few nanometers. The photolithography technique for manufacturing the transistor needs to reduce the wavelength of the optical wave, from ultraviolet to the extreme ultraviolet radiation. One approach toward decreasing the working wavelength is using lithography based on beyond extreme ultraviolet radiation (BEUV) with a wavelength around 7 nm. The BEUV lithography relies on advanced reflective optics such as periodic multilayer film X-ray mirrors (PMMs). PMMs are artificial Bragg crystals having alternate layers of “light” and “heavy” materials. The periodicity of such a structure is relatively half of the working wavelength. Because a BEUV lithographical system contains at least 10 mirrors, the optics’ reflectivity becomes a crucial point. The increasing of a single mirror’s reflectivity by 10% will increase the system’s overall throughput six-fold. In this work, the properties and development status of PMMs, particularly for BEUV lithography, were reviewed to gain a better understanding of their advantages and limitations. Emphasis was given to materials, design concepts, structure, deposition method, and optical characteristics of these coatings.

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Section: Structural and Optical Propertiesmentioning

confidence: 99%

Multilayer Reflective Coatings for BEUV Lithography: A Review

Uzoma

Salman

et al. 2021

Nanomaterials

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show abstract

“…In addition to the intermixing, the interface roughness is another factor crucial for reflectivity. It was shown that adjusting the pressure in the deposition step can significantly reduce the interface roughness in Mo/Si PMMs [45]. On the other hand, the roughness is also affected by the thickness of individual layers [46].…”

Section: Structural and Optical Propertiesmentioning

confidence: 99%

Multilayer Reflective Coatings for BEUV Lithography: A Review

Uzhoma¹,

Shabir²,

Hu³

et al. 2021

Preprint

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The development of microelectronics is always driven by reducing transistor size and increasing integration, from the initial micron-scale to the current few nanometers. The photolithography technique for manufacturing the transistor needs to reduce the wavelength of the optical wave, from ultraviolet, deep, to the existing extreme ultraviolet light. One approach toward decreasing the working wavelength is using lithography based on beyond extreme ultraviolet radiation (BEUV) with a wavelength around 7 nm. The BEUV lithography relies on advanced reflective optics such as periodic multilayer film X-ray mirrors (PMMs). PMMs are artificial Bragg crystals having alternate layers of “light” and “heavy” materials. The periodicity of such a structure is relatively half of the working wavelength. Since a BEUV lithographical system contains at least 10 mirrors, optics’ reflectivity becomes a crucial point. The increasing of a single mirror's reflectivity by 10% will increase the system’s overall throughput by 6 times. In this work, the properties and development status of PMMs, particularly for BEUV lithography, were reviewed to gain a better understanding of their advantages and limitations. Emphasis was given to materials, design concepts, structure, deposition method, and optical characteristics of these coatings.

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“…Из данных, приведенных в данном подразделе, следует, что для многослойной системы W-Si возможно 2 подхода к снижению взаимодействия на межфазных границах Si и W: 1) уменьшение энергии распыленных атомов, например путем понижения напряжения горения магнетронов либо повышения давления рабочего газа с целью термализации распыленных атомов [44]; 2) снижение скорости осаждения. Снижение энергии осаждаемых атомов может вызвать развитие шероховатости [45].…”

Section: механизм роста силицидных прослоекunclassified

STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS

Pershyn

Shipkova

Devizenko

et al. 2018

EEJP

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X-ray diffractometry in a hard region (l~0.154 nm) was used to study the phase structure, composition and construction of W/Si multilayer X-ray mirrors (MXMs) with thicknesses of tW<10 nm for tungsten layers obtained by direct-current magnetron sputtering. Two series of samples were fabricated with different tungsten deposition rates, which differ approximately by a factor of 4: ~0.60 nm/s and ~0.15 nm/s. It is shown that tungsten layers have a polycrystalline (BCC) structure at thicknesses tW>2.7 nm, and at tW<1.9 nm they are amorphous. Using the sin2Y-method, it was found that in thin crystalline layers of tungsten (tW<10 nm), more than 3 at.% Si can be contained. Tensile stresses in the layers of crystalline tungsten do not exceed 1.1 GPa. The construction of the radial distribution functions of atoms made it possible to establish that amorphous layers of tungsten have an arrangement of atoms close to b-W. In all samples, formation of silicide interlayers is observed at the interfaces, as a result of which the actual thickness of the tungsten layers is less than the nominal one. Amorphous silicide layers, necessarily formed at the stage of MXM manufacturing, contain tungsten disilicide. Depending on the deposition rate, disilicide can have an arrangement of atoms close to either the tetragonal phase, t-WSi2 (~0.6 nm/s), or to the hexagonal phase, h-WSi2 (~0.15 nm/s). An improved model for the construction of amorphous W/Si MXMs is presented. Mechanisms for the formation of silicide layers are proposed, according to which the bottom silicide interlayers (W-on-Si) are formed mainly by ballistic mixing of tungsten and silicon atoms, and the top ones due to diffusion inermixing. The interdiffusion coefficients were estimated, which made it possible to establish that the deposited surface of the layers can be heated at least 250° above the substrate temperature. The ways of reducing the interface interaction are suggested.

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Effect of working gas pressure on interlayer mixing in magnetron-deposited Mo/Si multilayers

Cited by 10 publications

References 59 publications

Multilayer Reflective Coatings for BEUV Lithography: A Review

Multilayer Reflective Coatings for BEUV Lithography: A Review

Multilayer Reflective Coatings for BEUV Lithography: A Review

STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS

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