CNT EUV pellicle: moving towards a full-size solution

Timmermans, Marina Y.; Pollentier, Ivan; Lee, Jae Uk; Meersschaut, Johan; Richard, Olivier; Adelmann, Christoph; Huyghebaert, Cedric; Gallagher, Emily

doi:10.1117/12.2280632

Cited by 6 publications

(6 citation statements)

References 24 publications

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“…XRR and AFM measurements were performed after finite cleaning cycles to study the impact of cleaning on TaCo thin films. In an EUV scanner operation, the mask is exposed in a hydrogen environment to maintain self-cleaning conditions for the sensitive EUV mirrors 28 by preventing it from carbon contamination 29 . Ta-Co alloy samples were exposed to hydrogen radicals for 24 hrs to test their stability.…”

Section: Methodsmentioning

confidence: 99%

“…In an EUV scanner operation, the mask is exposed in a hydrogen environment to maintain self-cleaning conditions for the sensitive EUV mirrors 28 by preventing it from carbon contamination. 29 Ta-Co alloy samples were exposed to hydrogen radicals for 24 hrs to test their stability. The radicals were generated by a heated tungsten filament in the "hydrogen cleaner" tool manufactured by EUVTech.…”

Section: Cleaning and Durability Testmentioning

confidence: 99%

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

Thakare

Opsomer

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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Background: A plausible approach for mitigating the mask 3-D (M3D) effects observed in extreme ultraviolet (EUV) lithography is to replace the existing mask absorber with alternative materials. Absorbers with a high EUV extinction coefficient k allow for lower best focus variation (BFV) through pitch and reduced telecentricity errors (TCEs).Aim: We aim to evaluate Ta-Co alloys as potential high-k mask absorbers from material suitability and imaging standpoints.Approach: We study the film morphology, surface composition, and stability of Ta-Co alloys in mask cleaning solutions and a hydrogen environment as present in the EUV scanner to assess the material suitability from an experimental aspect. Optical constants for three selected compositions, viz., TaCo, Ta 2 Co, and TaCo 3 , were determined from EUV angle-dependent reflectivity measurements. Next, utilizing rigorous simulation software, the imaging performance of Ta-Co alloys is evaluated and compared with the reference absorber. The recommended absorber thickness for Ta-Co alloy absorbers is based upon normalized image log slope (NILS) enhancement, threshold to size, and balancing of diffraction order amplitudes. A 10 nm line and space pattern with a pitch of 20 nm and 14 nm square contact holes with a pitch of 28 nm are used for the simulation study using high numerical aperture 0.55 EUV lithography process settings. The primary imaging metrics for through pitch evaluation include NILS, TCE, and BFV. Results:The Ta-Co alloys exhibit a higher EUV extinction coefficient k compared with the currently used Ta-based absorber. TaCo and Ta 2 Co demonstrate smooth surfaces and are stable in a hydrogen environment and in mask-cleaning solutions. Conclusion:Ta-Co alloys allow for a reduction in M3D effects at a lower absorber thickness compared with a 60 nm Ta-based reference absorber.

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Section: Methodsmentioning

confidence: 99%

Section: Cleaning and Durability Testmentioning

confidence: 99%

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

Thakare

Opsomer

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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“…Various types of pellicle membranes have been evaluated and tested both experimentally and with simulations to assess their mechanical and optical characteristics. [6][7][8][9] Among them, CNT pellicles proved to be a promising option with high EUV transmission (up to ∼99%), low reflectivity 0.001%, and good mechanical stability (<0.08 mm deflection under a 2-Pa pressure for a 10 × 10 mm 2 sample). 6,10 The lifetime of CNT membranes can be limited by the exposure to hydrogen ions generated by EUV radiation inside the scanner.…”

Section: Pellicle Samplesmentioning

confidence: 99%

“…Scanning electron micrographs of (a) random CNT membrane consisting of SW CNTs as shown with transmission electron micrograph at the inset and (b) aligned CNT membrane consisting of MW CNTs as shown with transmission electron micrograph at the inset 6. …”

mentioning

confidence: 99%

Experimental evaluation of the impact of carbon nanotube EUV pellicles on reticle imaging

Mochi

Timmermans

Gallagher

et al. 2019

J. Micro/Nanolith. MEMS MOEMS

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Background: The purpose of EUV pellicles is to protect the surface of EUV lithography masks from particle contamination. It is important to ensure that the optical characteristics of the pellicle membrane do not critically affect the reticle image quality. Aim: We want to verify the possibility to integrate pellicle inspection and characterization capabilities in reflective-mode EUV mask scanning microscope (RESCAN), our actinic mask inspection platform based on coherent diffraction imaging. Approach: We studied the impact of a few selected EUV pellicle prototypes on the quality and the contrast of the reticle image obtained with RESCAN. Results: We measured the scattering distribution of the pellicles, and we correlated it with the mask image contrast and fidelity. We also detected the presence of a 6.5-μm-diameter fiber on the pellicle surface. Conclusions: We demonstrated that RESCAN is suitable for through-pellicle actinic mask inspection and can be also used to characterize and monitor the pellicle quality.

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“…Hydrogen possesses a low molecular weight and high chemical reactivity, making it an attractive candidate for such applications. However, its propensity to damage materials poses a threat to many of its applications. ,, Therefore, understanding the interaction of hydrogen with surfaces is critical for (further) development of its applications.…”

Section: Introductionmentioning

confidence: 99%

Chemical Interaction of Hydrogen Radicals (H*) with Transition Metal Nitrides

Rehman,

van de Kruijs,

van den Beld

et al. 2023

J. Phys. Chem. C

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Transition metal nitrides (TMNs) are reported as protective coatings in reactive hydrogen environments. Although the permeation of H 2 through TMN coatings is well reported, their reducibility in H* environments is less investigated. In this work, we categorize the interaction of H* with ambient exposed TiN, ZrN, HfN, VN, NbN, and TaN thin films at 700 °C into three classes. We find that in TiN and VN samples, H*-induced reduction was limited to the surface (≈ top 2 nm). Significant denitridation was observed in ZrN and HfN samples beneath the surface, along with an increase in the transition metal oxide (TMO x ) fraction. Denitridation was observed in NbN and TaN samples as well, but the increase in the TMO x content was less than for ZrN and HfN. We propose a model in three steps: hydrogenation, formation of volatile species, and diffusion of subsurface atoms to the surface. We show that the interaction of H* with TiN, ZrN, HfN, VN, NbN, and TaN with partially oxidized surfaces can be explained using the preferred hydrogenation pathway (based on the work functions) and the thermodynamic driver for forming volatile species (NH 3 and H 2 O; based on the change in Gibbs free energy).

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CNT EUV pellicle: moving towards a full-size solution

Cited by 6 publications

References 24 publications

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

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

Experimental evaluation of the impact of carbon nanotube EUV pellicles on reticle imaging

Chemical Interaction of Hydrogen Radicals (H*) with Transition Metal Nitrides

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