Dr. Karl Opsomer Profile

Dr. Karl Opsomer

at imec

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Author

Publications (8)

SPIE Journal Paper | 21 June 2023

Evaluation of Ta-Co alloys as novel high-k extreme ultraviolet mask absorber

Devesh Thakare, Meiyi Wu, Karl Opsomer, Qais Saadeh, Victor Soltwisch, Philipp Naujok, Christophe Detavernier, Davide Dattilo, Markus Foltin, Andy Goodyear, Mike Cooke, Annelies Delabie, Vicky Philipsen

JM3, Vol. 22, Issue 02, 024403, (June 2023) https://doi.org/10.1117/12.10.1117/1.JMM.22.2.024403

KEYWORDS: Alloys, Extreme ultraviolet, Tantalum, Nanoimprint lithography, Etching, Oxides, Silicon, Ruthenium, Light sources and illumination, Film thickness

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Proceedings Article | 26 May 2022 Presentation + Paper

Evaluation of Ta-Co alloys as novel high-k EUV mask absorber

Devesh Thakare, Meiyi Wu, Karl Opsomer, Christophe Detavernier, Philipp Naujok, Qais Saadeh, Victor Soltwisch, Annelies Delabie, Vicky Philipsen

Proceedings Volume 12051, 120510D (2022) https://doi.org/10.1117/12.2614235

KEYWORDS: Tantalum, Extreme ultraviolet, Photomasks, Cobalt, Extreme ultraviolet lithography

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Proceedings Article | 12 October 2021 Presentation + Paper

First results of EUV-scanner compatibility tests performed on novel 'high-NA' reticle absorber materials

Jetske Stortelder, Rob Ebeling, Corné Rijnsent, Michel van Putten, Véronique de Rooij-Lohmann, Maximilian Smit, Arnold Storm, Norbert Koster, Henk Lensen, Vicky Philipsen, Karl Opsomer, Devesh Thakare, Torsten Feigl, Philipp Naujok

Proceedings Volume 11854, 1185414 (2021) https://doi.org/10.1117/12.2600928

KEYWORDS: Extreme ultraviolet lithography, Hydrogen, Reticles, Extreme ultraviolet, Plasma, Scanners, EUV optics, Accelerated life testing, Materials analysis, Extreme ultraviolet coatings, Contamination control

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Novel reticle absorber materials are required for high-NA EUV lithography. TNO and ASML developed an assessment for the compatibility of novel high-NA reticle absorber materials with conditions that mimic the EUV scanner environment^[1]. Four candidate reticle absorber materials were evaluated, TaCo, RuTa, PtMo and Pt2Mo alloys, in a joint research program. For the compatibility tests, dedicated samples with silicon wafer substrates were fabricated. The silicon wafers were coated with a Mo-Si multilayer coating, followed by a Ru capping layer and finally the absorber material.

Chemical outgassing tests, in presence of hydrogen radicals, did not show chemical outgassing for the TaCo and PtMo alloys. RuTa and Pt₂Mo alloys were not tested, based upon their elemental composition chemical outgassing is not expected. Next, all four materials were exposed in a hydrogen plasma resistance test equivalent to an EUV exposure of at least 250 thousand wafers** in the EUV scanner. No plasma-induced defects, like blistering or delamination, were found that were related to the intrinsic absorber properties.

The RuTa and PtMo alloys were selected for EUV exposure in the EBL2 facility at TNO. Both materials were exposed to an 9.6 kJ/mm² EUV peak dose at an EUV peak intensity of 450 mW/mm² in a hydrogen environment. This EBL2 EUV exposure of 6 hours represents about 1-2 months of EUV dose (at least 150 thousand wafers) in a NXE or EXE scanner with a 300 W source. Both materials showed good performance during EUV exposure. Relevant surface defects and chemical outgassing were not observed. The few observed blisters in the low EUV intensity areas are likely provoked by particle contamination or coating defects.

All four absorber materials, TaCo, RuTa, PtMo and Pt₂Mo alloys performed well in the compatibility tests that were executed. Not all compatibility tests could be performed on each absorber material within the scope of our research program. Further testing would be needed to complete the compatibility assessment, including an EUV exposure on a patterned reticle.

Proceedings Article | 20 June 2021 Presentation

Optical constants for EUV scatterometry

Richard Ciesielski, Qais Saadeeh, Philipp Naujok, Karl Opsomer, Jean-Philippe Soulié, Meiyi Wu, Vicky Philipsen, Robbert W.. van de Kruijs, Michael Kolbe, Frank Scholze, Victor Soltwisch

Proceedings Volume 11783, 117830M (2021) https://doi.org/10.1117/12.2592543

KEYWORDS: Reflectivity, Photomasks, Data modeling, X-rays, Thin films, Statistical modeling, Semiconductors, Scattering, Phase shifting, Nanostructures

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SPIE Journal Paper | 3 May 2021

Study of novel EUVL mask absorber candidates

Meiyi Wu, Devesh Thakare, Jean-François de Marneffe, Patrick Jaenen, Laurent Souriau, Karl Opsomer, Jean-Philippe Soulié, Andreas Erdmann, Hazem M. Mesilhy, Philipp Naujok, Markus Foltin, Victor Soltwisch, Qais Saadeh, Vicky Philipsen

JM3, Vol. 20, Issue 02, 021002, (May 2021) https://doi.org/10.1117/12.10.1117/1.JMM.20.2.021002

KEYWORDS: Photomasks, Extreme ultraviolet lithography, Extreme ultraviolet, Nanoimprint lithography, Etching, Ruthenium, Refractive index, Optical lithography, Semiconducting wafers, Thin films

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Novel mask absorber designs are catching the attention of the EUVL community due to their ability to mitigate mask 3D effects. Material selection is part of such an optimization. We propose several candidates as novel EUV lithography mask absorbers, namely TaTeN, Ru–Ta, and Pt–Mo alloys. The choice of these materials is based on their theoretical performance evaluated by EUV imaging simulation based on their complex refractive index N ( λ ) = n ( λ ) + ik ( λ ) , where the optical constants n and k relate to the phase velocity and the absorption of electromagnetic radiation with a wavelength λ, respectively. The materials are deposited as thin films on Si substrate with an additional Ru layer to mimic the cap of the multilayer mirror on the real mask. The experimental n and k values are determined by analyzing EUV reflectivity data obtained using a 13.5-nm synchrotron EUV radiation. The imaging simulation presented consists of calculating several imaging metrics including non-telecentricity, normalized image log-slope, and threshold-to-size for specific use cases using the novel absorber. It also compares the proposed materials with the reference TaBN absorber. TaTeN shows higher absorption than TaBN and refraction closer to 1, which improves phase matching for a high k absorber. The refractive index of Ru–Ta and Pt–Mo alloys exhibits a large difference from that of air and provides the required phase shift of attenuated phase shift masks. The characterizations of these materials target the requirements of an EUVL mask: durability for mask cleaning, mask lifetime, and etchability for mask patterning. The stability is first tested against several standard mask cleaning solutions by a beaker test for up to 24 h. The samples are also exposed to hydrogen plasma to imitate the working environment in an EUV scanner. Concerning material patterning, chemical reactive ion etch is applied for preliminary tests. A proper etch recipe is found for TaTeN with a good etch rate (about 60 nm / min) and good selectivity to the Ru underlayer (Ru etch is negligible).

Proceedings Article | 20 October 2020 Presentation + Paper

Mask absorber for next generation EUV lithography

Meiyi Wu, Devesh Thakare, Jean-François de Marneffe, Patrick Jaenen, Laurent Souriau, Karl Opsomer, Jean-Philippe Soulié, Andreas Erdmann, Hazem Mesilhy, Philipp Naujok, Markus Foltin, Victor Soltwisch, Qais Saadeh, Vicky Philipsen

Proceedings Volume 11517, 1151706 (2020) https://doi.org/10.1117/12.2572114

KEYWORDS: Photomasks, Extreme ultraviolet lithography, Extreme ultraviolet, Etching, Ruthenium, X-rays, Refractive index, Reflectivity, Phase shifts, Mask cleaning

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Novel mask absorber designs are calling attention of the EUVL community due to their ability to mitigate mask 3D effects. Material selection is part of such optimization [1]. In this paper we propose several candidates as novel EUV lithography mask absorbers, namely TaTeN, Ru-Ta and Pt-Mo alloys. The choice of these materials is based on their theoretical performance evaluated by EUV imaging simulation based on their complex refractive index N(λ) = n(λ) +ik(λ), where the optical constants n and k relate to the phase velocity and to the absorption of an electromagnetic radiation with a wavelength λ, respectively. The materials are deposited as thin films on Si substrate with an additional Ru layer to mimic the cap of multilayer mirror (MLM) on the real mask. The experimental n and k values are determined by analyzing EUV reflectivity data obtained using a 13.5 nm synchrotron EUV radiation. The imaging simulation presented in this paper consists of calculation of several imaging metrics like non-telecentricity, normalized image log-slop (NILS), and threshold-to-size for specific use cases using the novel absorber. It also compares the proposed materials to the reference TaBN absorber. TaTeN shows higher absorption than TaBN and refraction closer to 1, which improves phase matching for a high k absorber. The refractive index of Ru-Ta and Pt-Mo alloys exhibits a large difference to that of air and provides the required phased shift of attenuated phase shift masks [2]. The characterizations of these materials target the requirements of an EUVL mask: durability for mask cleaning, mask lifetime and etchablity for mask patterning. The stability is first tested against several standard mask cleaning solutions by beaker test up to 24 hours with the film structure monitored by X-ray reflectivity analysis. The samples are also exposed to hydrogen plasma to imitate the working environment in a EUV scanner. Material integrity is checked with Rutherford backscattering spectroscopy before and after the exposure. Concerning material patterning, chemical reactive ion etch is applied for preliminary tests. A proper etch recipe is found for TaTeN with good etch rate (about 60 nm/min) and good selectivity to Ru underlayer (Ru etch is ignorable).

Proceedings Article | 27 June 2019 Paper

Mask absorber development to enable next-generation EUVL

Vicky Philipsen, Kim Vu Luong, Karl Opsomer, Laurent Souriau, Jens Rip, Christophe Detavernier, Andreas Erdmann, Peter Evanschitzky, Christian Laubis, Philipp Hönicke, Victor Soltwisch, Eric Hendrickx

Proceedings Volume 11178, 111780F (2019) https://doi.org/10.1117/12.2537967

KEYWORDS: Photomasks, Extreme ultraviolet, Extreme ultraviolet lithography, Metals, Plasma etching, Etching, Optical properties

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Proceedings Article | 10 October 2018 Presentation + Paper

Novel EUV mask absorber evaluation in support of next-generation EUV imaging

Vicky Philipsen, Kim Vu Luong, Karl Opsomer, Christophe Detavernier, Eric Hendrickx, Andreas Erdmann, Peter Evanschitzky, Robbert W. van de Kruijs, Zahra Heidarnia-Fathabad, Frank Scholze, Christian Laubis

Proceedings Volume 10810, 108100C (2018) https://doi.org/10.1117/12.2501799

KEYWORDS: Material characterization, Photomasks, Extreme ultraviolet, Metals, Tellurium, Extreme ultraviolet lithography, Refractive index

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In next-generation EUV imaging for foundry N5 dimensions and beyond, inherent pitch- and orientation-dependent effects on wafer level will consume a significant part of the lithography budget using the current Ta-based mask. Mask absorber optimization can mitigate these so-called mask 3D effects. Thin metal absorbers like Ni and Co have been experimentally investigated due to their high EUV absorption, but they pose challenges on the current technology of subtractive mask patterning [1]. A simulation study of attenuated EUV phase shift masks has identified through multiobjective optimization superior imaging solutions for specific use cases and illumination conditions [2]. Evaluating novel EUV mask absorbers evolves on two levels, demonstrating (1) improvements from lithographic perspective and (2) compatibility with the full mask supply chain including material deposition, absorber patterning, scanner environment compatibility and mask lifetime. On the lithographic level, we have identified regions based on the material optical properties and their gain in imaging performance compared to the reference Ta-based absorber. Within each improvement region we engineered mask absorber materials to achieve both the required imaging capabilities, as well as the technical requirements for an EUV mask absorber. We discuss the material development of Te-based alloys and Ag-based layered structures, because of their high EUV extinction. For the attenuated phase shift materials, we start from a Ru-base material, due to its low refractive index, and construct Ru-alloys. On the experimental level, we examined our novel mask absorber materials against an initial mask absorber requirement list using an experimental test flow. Candidate materials are evaluated on film morphology and stability through thermal, hydrogen, EUV loading, and chemical cleaning, for their EUV optical constants by EUV reflectometry, as well as preliminary for selective dry etch. The careful mask absorber evaluation, combining imaging simulations and experimental material tests, allowed us to narrow down to promising combinations for novel EUV mask absorbers.

Showing 5 of 8 publications

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