Improved Ru/Si multilayer reflective coatings for advanced extreme-ultraviolet lithography photomasks

Wood, O. R.; Wong, Keith H.K.; Parks, Valentin; Kearney, Patrick A.; Meyer-Ilse, Julia; Luong, Vu; Philipsen, Vicky; Faheem, Mohammad; Liang, Yifan; Kumar, Ajay; Chen, Esther; Bennett, Corbin; Fu, Bianzhu; Gribelyuk, M.; Zhao, Wayne; Mangat, Pawitter J. S.; Heide, Paul van der

doi:10.1117/12.2219215

Cited by 10 publications

(12 citation statements)

References 3 publications

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“…For instance, due to the short wavelength of the EUV radiation, the absorption (and thus the energy loss of the EUV light) is one of the biggest challenges in EUVL. To mitigate this problem, photomasks with alternative materials to the commonly used Mo/Si multilayer (ML) reflector and patterned Ta-based absorber (both of which are known to require shadow effect corrections and lead to large throughfocus pattern placement errors) are being actively explored [2].…”

Section: Introductionmentioning

confidence: 99%

Comparison of EUV Photomask Metrology Between CD-AFM and TEM

et al. 2022

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Accurate metrology of extreme ultraviolet (EUV) photomask is a crucial task. In this paper, two different methods for reference EUV photomask metrology are compared. One is the critical dimension atomic force microscopy (CD-AFM). In the measurements, the contribution of its AFM tip geometry is usually the dominant error source, as measured AFM images are the dilated results of measured structures by the AFM tip geometry. To solve this problem, a bottom-up approach has been applied in calibrating the (effective) AFM tip geometry where the result is traceably calibrated to the lattice constant of silicon crystals. The other is transmission electron microscopy (TEM). For achieving measurement traceability, structure features are measured in pairs in TEM images; thus the distance between the structure pair calibrated by a metrological AFM in prior can be applied to determine the magnification of the TEM image. In this study, selected photomask structures are calibrated by the CD-AFM, and then sample prepared and measured by high-resolution TEM nearly at the same location. The results are then compared. Of six feature groups compared, the results agree well within the measurement uncertainty, indicating excellent performance of the developed methodology. This research supports the development of a photomask standard, which is applied as a “reference ruler” with improved low measurement uncertainty in photomask fabs.

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Section: Introductionmentioning

confidence: 99%

Comparison of EUV Photomask Metrology Between CD-AFM and TEM

et al. 2022

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“…To extract material and optical properties for the systems in Figure 4, we utilize the commercial software IMD [17] in combination with a physical model of each system that considers surface contamination/oxidation, as well as interface formation and layer mixing (if present). As the presence of oxide and interfacial layers can vary depending on the material system, we choose these three model systems as they each represent a category of materials where a) no oxide and intermixing is expected (TiN), b) only oxidation of the surface is expected (Nb), and c) where oxidation and interfacial layer formation are known to occur (Ru) [2,19]. In Table 2 we show the results of the fitting for these 3 model systems.…”

Section: Actinic Euv Reflectometry Of Thin Film Systemsmentioning

confidence: 99%

Actinic inspection of the EUV optical parameters of lithographic materials with lab-based radiometry and reflectometry

Dorney

Kissoon

Holzmeier

et al. 2023

Optical and EUV Nanolithography XXXVI

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The interaction of EUV light with matter is a critical step in EUV lithographic processes and optimization of the optical material parameters of photoresists and reflector/absorber stacks is crucial to harness the full power of EUV lithography. To optimize these materials, accurate measurements of EUV absorption and reflection are needed to extract the corresponding actinic optical properties and structural parameters. Here, we report on two endstations within imec’s AttoLab that enable actinic EUV absorption and reflection measurements. We commission these tools with measurements on model thin film and photoresist systems and provide extracted optical parameters as well as absorption kinetics, respectively. These results showcase the power of these tools for providing crucial data for material optimization and lithographic simulation.

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“…Replacement of Mo by ruthenium (Ru) with a slightly lower refractive index can help to reduce the distance between the effective reflection plane and the top of the multilayer to <40 nm. 23 The modified weighting of (double diffracted) orders in aperiodic or quasiperiodic MoSi bilayer systems can mitigate the 3D mask effects for specific pitches. [24][25][26] However, at the cost of the imaging performance at other pitches.…”

Section: Paths Toward Mitigationmentioning

confidence: 99%

Perspectives and tradeoffs of absorber materials for high NA EUV lithography

Erdmann

Mesilhy

Evanschitzky

et al. 2020

J. Micro/Nanolith. MEMS MOEMS

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Next-generation extreme ultraviolet (EUV) systems with numerical apertures of 0.55 have the potential to provide sub-8-nm half-pitch resolution. The increased importance of stochastic effects at smaller feature sizes places further demands on scanner and mask to provide high contrast images. We use rigorous mask diffraction and imaging simulation to understand the impact of the EUV mask absorber and to identify the most appropriate optical parameters for high NA EUV imaging. Simulations of various use cases and material options indicate two main types of solutions: high extinction materials, especially for lines spaces, and low refractive index materials that can provide phase shift mask solutions. EUV phase masks behave very different from phase shift masks for DUV. Carefully designed low refractive index materials and masks can open up a new path toward high contrast edge printing. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Improved Ru/Si multilayer reflective coatings for advanced extreme-ultraviolet lithography photomasks

Cited by 10 publications

References 3 publications

Comparison of EUV Photomask Metrology Between CD-AFM and TEM

Comparison of EUV Photomask Metrology Between CD-AFM and TEM

Actinic inspection of the EUV optical parameters of lithographic materials with lab-based radiometry and reflectometry

Perspectives and tradeoffs of absorber materials for high NA EUV lithography

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