High-NA EUV lithography: pushing the limits

Zahlten, C.; Gräupner, Paul; Schoot, Jan van; Kürz, P.; Stoeldraijer, Judon; Kaiser, Winfried

doi:10.1117/12.2536469

Cited by 29 publications

(27 citation statements)

References 3 publications

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“…To advance from N5 to the future foundry technology nodes, a further reduction in feature sizes is again required. This further development of EUVL is heavily based on fabricating an optical system that can support a larger numerical aperture (NA), i.e., a larger lens system, in the so-called high NA EUVL [3]. This system, with an increase in NA value of 0.33 to 0.55, can capture diffraction 2 of 15 orders over a larger area.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Response Spectroscopy as Means to Investigate Interfacial Effects for Ultra-Thin Film Polymer-Based High NA EUV Lithography

2020

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Extreme ultra-violet lithography (EUVL) is the leading-edge technology to produce advanced nanoelectronics. The further development of EUVL is heavily based on implementing the so-called high numerical aperture (NA) EUVL, which will enable even smaller pitches up to 8 nm half pitch (HP). In anticipation of this high NA technology, it is crucial to assess the readiness of the current resist materials for the high NA regime to comply with the demanding requirements of resolution, line-edge roughness, and sensitivity (RLS). The achievable tighter pitches require lower film thicknesses for both resist and underlying transfer layers. A concern that is tied to the thinning down is the potential change in resist properties and behavior due to the interaction with the underlayer. To increase the fundamental understanding of ultra-thin films for high NA EUVL, a method to investigate the interplay of reduced film thickness and different patterning-relevant underlayers is developed by looking at the glass transition temperature (Tg) of polymer-based resists. To minimize the ambiguity of the results due to resist additives (i.e., photoacid generator (PAG) and quencher), it was opted to move forward with polymer-only samples, the main component of the resist, at this stage of the investigation. By using dielectric response spectroscopy, the results obtained show that changing the protection group of the polymer, as well as altering the polymer film thickness impacts the dynamics of the polymer mobility, which can be assessed through the Tg of the system. Unexpectedly, changing the underlayer did not result in a clear change in the polymer mobility at the tested film thicknesses.

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Section: Introductionmentioning

confidence: 99%

Dielectric Response Spectroscopy as Means to Investigate Interfacial Effects for Ultra-Thin Film Polymer-Based High NA EUV Lithography

2020

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“…Detailed knowledge on how EUV radiation interacts with matter is crucial to design photosensitive materials that resolve the projected images into nanopatterns, that is, photoresists. − In particular, the role of the electron cascade generated after photoionization, the mechanisms leading to the solubility switch, the influence of optional post-exposure procedures, and the blur resulting from the aforementioned processes are still being investigated. , Furthermore, as the nanopatterns’ size decreases, thinner photoresists are required to avoid high aspect ratios and pattern collapse, , which has two main consequences from a scientific perspective: (1) a more efficient EUV absorptivity is needed; (2) the roles of interfaces (photoresist-vacuum and photoresist-wafer) become more important for the formation of the nanostructures. Consequently, new concepts and designs of systems that can effectively react to radiation with nanoscale spatial resolution should be explored and accompanied by investigations of the fundamental aspects of their functioning to fulfil the requirements of upcoming nanofabrication technologies.…”

Section: Introductionmentioning

confidence: 99%

Bottom-Up Nanofabrication with Extreme-Ultraviolet Light: Metal–Organic Frameworks on Patterned Monolayers

Lugier

Thakur

et al. 2021

ACS Appl. Mater. Interfaces

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The fabrication of integrated circuits with ever smaller (sub-10 nm) features poses fundamental challenges in chemistry and materials science. As smaller nanostructures are fabricated, thinner layers of materials are required, and surfaces and interfaces gain a more important role in the formation of nanopatterns. We present a new bottom-up approach in which we use the high optical resolution offered by extreme ultraviolet (EUV) lithography to print patterns on self-assembled monolayers (SAMs). Upon radiation, low-energy electrons induce chemical changes in the SAM so that the projected image is transferred to the substrate surface. We use the chemical differences between exposed and unexposed regions to promote a selective growth of hybrid structures that can act as an etch-resistant layer for further pattern transfer or can be used as functional nanostructures. The EUV doses required to promote selective growth on exposed areas are close to industrial requirements. Furthermore, this method allows for the independent tuning of different steps in the EUV lithography process (photo-induced chemistry, spatially resolved chemical contrast, and formation of nanopatterns), an advantage over current resists, in which the same material plays all roles.

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“…A reduction of higher-order aberrations is possible by adding more curved optical elements in the design of a dioptric system [ 4 ], but outcome radiation is drastically reduced as a consequence. The EUV lithography industry has posed a constraint of a numerical aperture (NA) from 0.15 to 0.5 on all-reflective objectives for rendering with resolutions below 30 nm [ 5 , 6 ]. However, to accomplish the desired spatial resolution, this numerical aperture has to be combined with a perfect alignment of the mirrors employed in the system.…”

Section: Introductionmentioning

confidence: 99%

Wavefront Sensing for Evaluation of Extreme Ultraviolet Microscopy

Ruiz-Lopez

Mehrjoo

Keitel

et al. 2020

Sensors

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Wavefront analysis is a fast and reliable technique for the alignment and characterization of optics in the visible, but also in the extreme ultraviolet (EUV) and X-ray regions. However, the technique poses a number of challenges when used for optical systems with numerical apertures (NA) > 0.1. A high-numerical-aperture Hartmann wavefront sensor was employed at the free electron laser FLASH for the characterization of a Schwarzschild objective. These are widely used in EUV to achieve very small foci, particularly for photolithography. For this purpose, Schwarzschild objectives require highly precise alignment. The phase measurements acquired with the wavefront sensor were analyzed employing two different methods, namely, the classical calculation of centroid positions and Fourier demodulation. Results from both approaches agree in terms of wavefront maps with negligible degree of discrepancy.

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High-NA EUV lithography: pushing the limits

Cited by 29 publications

References 3 publications

Dielectric Response Spectroscopy as Means to Investigate Interfacial Effects for Ultra-Thin Film Polymer-Based High NA EUV Lithography

Dielectric Response Spectroscopy as Means to Investigate Interfacial Effects for Ultra-Thin Film Polymer-Based High NA EUV Lithography

Bottom-Up Nanofabrication with Extreme-Ultraviolet Light: Metal–Organic Frameworks on Patterned Monolayers

Wavefront Sensing for Evaluation of Extreme Ultraviolet Microscopy

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