Thermal stability of B-based multilayer mirrors for next generation lithography

Naujok, Philipp; Murray, Kirk; Yulin, Sergiy; Patzig, Christian; Kaiser, Norbert; Tünnermann, Andreas

doi:10.1016/j.tsf.2017.09.033

Cited by 10 publications

(8 citation statements)

References 18 publications

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“…To better understand the effect of thermal stability on PMMs, Naujok and co-workers [63] investigated the change in the microstructure and reflective properties of La/B 4 C and LaN/B 4 C PMMs prepared for high reflectivity at λ = 6.7 nm and annealed at elevated temperatures ≤800 • C. They analyzed the thermally induced changes in the internal structure of the PMMs, such as the elemental distribution, period thickness, crystallinity, and optical reflectivity. At temperatures ≤300 • C, there was no noticeable change in the period thickness of La/B4C PMMs.…”

Section: Thermal Stability Of the Beuv Pmmsmentioning

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: Thermal Stability Of the Beuv Pmmsmentioning

confidence: 99%

Multilayer Reflective Coatings for BEUV Lithography: A Review

Uzoma

Salman

et al. 2021

Nanomaterials

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“…To better understand the effect of thermal stability on PMMs, Naujok and co-workers [64] investigated the change in the microstructure and reflective properties of La/B4C and LaN/B4C PMMs prepared for high reflectivity at λ = 6.7 nm and annealed at elevated temperatures ≤ 800 °C. They analyzed the thermally induced changes in the internal structure of the PMMs such as the elemental distribution, period thickness, crystallinity, and optical reflectivity.…”

Section: Thermal Stability Of the Beuv Pmmsmentioning

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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“…5 middle). However, due to imperfect film growth and interdiffusion at the interfaces, such high optical performance cannot be achieved practically in real mirrors [26]. It should also be noted that La/B mirrors are extremally narrowband in their spectral reflectance properties (FWHM = 0.065 nm) in comparison to conventional Mo/Si mirrors (FWHM = 0.6 nm) that can considerably mitigate an optical throughput of lithographic systems (Fig.…”

Section: La/b Coatings For Beyond Euvlithographymentioning

confidence: 99%

“…The highest reported reflectivity of 64.1 % at 6.63 nm was achieved recently by B/La/LaN mirrors [27] that are close to the current requirements of the semiconductor industry. Besides high reflectivity, the industry demands low-stress coatings that may withstand elevated temperatures up to 200 °C [26]. After annealing up to 250 °C, LaN/B 4 C multilayer showed slight reflection losses of only 3 % [26].…”

Section: Middle)mentioning

confidence: 99%

“…Besides high reflectivity, the industry demands low-stress coatings that may withstand elevated temperatures up to 200 °C [26]. After annealing up to 250 °C, LaN/B 4 C multilayer showed slight reflection losses of only 3 % [26]. Even after tempering at 800 °C for 10 hours, a reflecting, periodical structure of the multilayer was sustained (Fig.…”

Section: Middle)mentioning

confidence: 99%

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Coatings with barrier layers for extreme‐short wavelengths

Yulin

Trost²,

Schwinde³

et al. 2021

Vak Forsch Prax

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SummaryOver the last few decades, remarkable progress has been made in the field of multilayer coatings for the EUV spectral region, mainly due to the demands of EUV lithography for the semiconductor industry. The progress is associated with a deep understanding of the multilayer film growth, application of advanced smoothing technologies for multilayer interfaces, as well as the development of modern deposition and characterization techniques. The projection optics precisely coated by Mo/Si mirrors with 70 % reflectivity is the heart of the performance of industrial EUVL steppers recently developed by ASML for high‐volume chip production. While the EUVL at 13.5 nm has just launched into the market, the first high‐performance LaN/B multilayer mirrors with reflectivity up to 61 % were developed for the next emerging lithography generation with a reduced wavelength of 6.6 nm. Recent technological progress in EUVL optics and radiation sources triggered the development of compact microscopes in the water window spectral range (2.4 – 4.4 nm). The optimization of the multilayer design and deposition process of Cr/V, Cr/Sc and Cr/C mirrors resulted in reflectivity of 14.5% at 2.42 nm, 27.0 % at 3.16 nm, and 15,6% at a wavelength of 4.42 nm, respectively. These promising and still not limiting results indicate a large potential for future application of multilayer coated optics in various application fields such as microscopy in the water window, plasma diagnostics, spectroscopy, and astrophysics.

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Thermal stability of B-based multilayer mirrors for next generation lithography

Cited by 10 publications

References 18 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

Coatings with barrier layers for extreme‐short wavelengths

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