Realization of sub-15-nm half-pitch EUV lithography by the application of functional spin-on glass

Liang, Yichen; Brakensiek, Kelsey E.; Lowes, Joyce; Chacko, Andrea M.; Zhang, Ruimeng; Driessche, Veerle Van; Lang, Xiaolong; Kasthuri, Jaishankar; Luo, Ming; Guerrero, Douglas J.

doi:10.1117/12.2610985

Cited by 5 publications

(9 citation statements)

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“…A series of coating materials for ultrathin interlayers, also referred to as primers, were prepared by diluting the appropriately hydrolyzed siloxanes with industrial solvents, i.e., propylene glycol methyl ether (PGME) and propylene glycol methyl ether acetate (PGMEA), at Brewer Science, Inc. 8,9 For comparison, spin-on glass (SOG) underlayers containing the same adhesive functional groups were synthesized via sol-gel method as the control.…”

Section: Sog Synthesis and Characterizationmentioning

confidence: 99%

“…Different from previously reported 5-nm SOG polymers with molecular weights of ~1,500-4,000, the primer consists of hydrolyzed small molecules with molecular weights from 200 to 500. According to previous research, lithography performance is dominated by the strong adhesive forces 11 ; therefore, two SOG copolymers (SOG 1 and SOG 2) and two SOG homopolymers (SOG 3 and SOG 4) containing the same adhesive groups were synthesized via sol-gel method at Brewer Science, Inc., (BSI) for better comparison. The general information is summarized in Table 1.…”

Section: Materials Synthesis and Characterizationmentioning

confidence: 99%

“…The surface energies of primers and SOGs, which are sums of dispersive (Van der Waals) and polar components, were calculated from the contact angle. In consideration of the compatibility with photoresist and substrate, the underlayers with a polarity of 5-25 mN/m 2 potentially lead to optimized coating quality 11 . As summarized in Table 2, the polar interactions from primers varied significantly at different temperatures compared to SOGs, further demonstrating a strong temperature dependence on priming efficiency.…”

Section: Characterization Of Coating Qualitymentioning

confidence: 99%

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Novel assist layers to enhance EUV lithography performance of photoresists on different substrates

Lowes

Zhang

et al. 2023

Advances in Patterning Materials and Processes XL

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In EUV lithography, good resist patterning requires an assist layer beneath it to provide adhesion to prevent pattern collapse of small features and allow for higher aspect ratios. In addition, future EUV high numerical aperture (NA) is expected to require a decrease in thickness from the overall patterning stack. In this study, we are exploring a fundamentally new approach to developing an alternative and cost-effective underlayer to functionalize surfaces and enable EUV patterning. Rather than forming a 5-nm polymer film between the resist and its substrate, we propose to modify the substrate by spin-coating a thinner layer. In contrast to conventional underlayers (5–10 nm), the substrate is modified by a sub-1-nm layer during baking. Comprehensive analysis of the surface modification and coating was conducted by GPC, ellipsometer, and contact angle to identify the structure, stability, coating quality, and surface energy. Lithographic performance of existing EUV resist with the assist of this thin layer on Si wafers and different silicon hardmasks was evaluated using NXE3400 EUV exposure system to print HP14nm line-space features. It has been demonstrated that this sub-1-nm layer is able to realize HP14nm with a wider process window, higher depth of focus, and lower LWR on a Si wafer. Moreover, a silicon hardmask that could not realize printable features had significantly improved lithographic performance with the assist of this layer. Comparisons were also made with the industry-standard HMDS priming. Systematic analysis indicates that a sub-1-nm layer exemplifies a novel and effective way to enhance photoresist-substrate compatibility and improve EUV lithographic performance.

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Section: Sog Synthesis and Characterizationmentioning

confidence: 99%

Section: Materials Synthesis and Characterizationmentioning

confidence: 99%

Section: Characterization Of Coating Qualitymentioning

confidence: 99%

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Novel assist layers to enhance EUV lithography performance of photoresists on different substrates

Lowes

Zhang

et al. 2023

Advances in Patterning Materials and Processes XL

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“…11 Previous studies on UL impact for CAR EUV with pitches of 32-28 nm have addressed improvement in sensitivity, line width roughness (LWR), resist profile, and stochastic defect-free process window. [12][13][14] Various physical and chemical properties of ULs have been explored for their influence on EUV lithography performance. For example, the surface tension of ULs is critical for increasing the adhesive work that reduces pattern collapse due to the unbalanced capillary forces during the developing process.…”

Section: Introductionmentioning

confidence: 99%

Lithography performance improvement of MOR by underlayers

Li,

Lu,

Grannemann

et al. 2024

Advances in Patterning Materials and Processes XLI

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Metal oxide resists (MORs) have become one of the most attractive photoresist platforms that allow for high resolution and etch bias of small features while having a robust lithography performance. In this work, we present our study about improving line fidelity and reducing the dose of MOR for line space EUV lithography by applying spin-on underlayers (ULs). It is known that MOR patterning is induced by the activation during exposure and condensation of the active sites. Herein, we discuss the influence of ULs on MOR performance. A series of ULs with various chemistry, thickness, or process conditions were screened with MOR using NXE3400 EUV exposure system to print 14-nm HP line-space features. The results show that the nanobridges and scum can be alleviated, while the remaining resist thickness after development can be improved by up to 20% along with 5 -10% dose reductions. A comprehensive assessment of the ULs encompassing various chemistries examines coating quality, uniformity, and surface energy. The discussion delves into the correlation between the surface properties including morphology, interaction, etc., and their respective impacts on lithography performance. Lastly, some spin-on ULs produce up to 75% reduction of metal diffusion from the MOR into the underlying layers.

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“…Particularly in the lithography area, electricity consumption is rated as a top problem to address, not only because of its environmental impact but also to the associated higher production costs. From a coater-developer track perspective, as illustrated in Figure 1, one of the challenges to be addressed is the significant power consumption incurred when baking underlayers at high temperatures, such as spin-on carbon (SOC) and spin-on glass (SOG) which are necessary to support the advancement of device fabrication with finer patterns and high etch resistance and improve lithography process margins 8 . In this study, we aim to contribute to sustainable semiconductors by introducing a new approach to cure underlayers using light as an alternative approach to the conventional thermal-crosslinking system that uses heat, to reduce electricity consumption.…”

Section: Introductionmentioning

confidence: 99%

Light-curable underlayers for non-baking process in EUV lithography

Baek,

Heo,

Vandereyken

et al. 2024

Advances in Patterning Materials and Processes XLI

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Underlayer materials account for the majority of electricity consumption in the lithography process because all tracks need to maintain a high temperature not only during the process time but also throughout the entire operational period. In this study, we propose a novel method that deviates from the conventional approach of utilizing thermoplastic materials as the underlayers for crosslinking, instead advocating for the use of light source for the crosslinking process, which potentially leads to reduced electricity consumption. Furthermore, some studies have shown that light-curable materials exhibit a higher degree of crosslinking compared to thermally cured materials, which implies that better crosslinking may provide better lithography performance. We evaluated light-curable materials based on the thermoplastic underlayers used in conventional EUV lithography.

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Realization of sub-15-nm half-pitch EUV lithography by the application of functional spin-on glass

Cited by 5 publications

References 0 publications

Novel assist layers to enhance EUV lithography performance of photoresists on different substrates

Novel assist layers to enhance EUV lithography performance of photoresists on different substrates

Lithography performance improvement of MOR by underlayers

Light-curable underlayers for non-baking process in EUV lithography

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