Role of low-energy electrons in the solubility switch of Zn-based oxocluster photoresist for extreme ultraviolet lithography

Rohdenburg, Markus; Thakur, Neha; Cartaya, René; Castellanos, Sonia; Swiderek, Petra

doi:10.1039/d1cp02334a

Cited by 22 publications

(22 citation statements)

References 34 publications

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“…As proposed before [ 14 , 16 , 17 ], the electron-induced fragmentation of precursors with carboxylate ligands is most likely triggered by ionization (see Figure 1 ). The present results indicate that carboxylate ligands with saturated side chains are more efficiently removed from the sublimate layer than the aromatic benzoate ligand.…”

Section: Discussionsupporting

confidence: 52%

“…The same QMS as for the ESD experiments was used to record reference mass spectra during leaking of the individual gases into the vacuum chamber. This provides for a more reliable analysis than the use of literature data because the sensitivity of the instrument decreases towards higher m / z ratios [ 17 ]. We note that three different alkenes can be formed by cleaving a hydrogen radical from the alkyl radical C 5 H 11 • that is released upon loss of CO 2 from Ag(I) 2,2-dimethylbutanoate ( Figure 8 ).…”

Section: Resultsmentioning

confidence: 99%

“… Fragmentation of carboxylate ligands in metal complexes initiated by ionization following electron impact, as proposed earlier [ 14 , 15 , 16 , 17 ]. Red arrows indicate the electron rearrangement that leads to release of CO 2 and an organic radical R • .…”

Section: Figurementioning

confidence: 85%

“…Figure 12 summarises this sequence of reactions. In principle, radical species can also add to double bonds [ 17 ], but these are absent from the intact adjacent molecules. Additionally, the radical site carries bulky substituents that hinder the approach towards a reaction partner.…”

Section: Discussionmentioning

confidence: 99%

“…The QMS was also used to measure mass spectra of 2-methyl-2-butene, CO 2 and H 2 O, which were needed as reference to fit the ESD data of Ag(I) 2,2-dimethylbutanoate. Note that the RGA employed in this study discriminates against high m / z ratios, which impedes the usage of listed reference MS data [ 17 ].…”

Section: Methodsmentioning

confidence: 99%

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Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition

et al. 2022

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Focused electron beam induced deposition (FEBID) is a versatile tool to produce nanostructures through electron-induced decomposition of metal-containing precursor molecules. However, the metal content of the resulting materials is often low. Using different Ag(I) complexes, this study shows that the precursor performance depends critically on the molecular structure. This includes Ag(I) 2,2-dimethylbutanoate, which yields high Ag contents in FEBID, as well as similar aliphatic Ag(I) carboxylates, aromatic Ag(I) benzoate, and the acetylide Ag(I) 3,3-dimethylbutynyl. The compounds were sublimated on inert surfaces and their electron-induced decomposition was monitored by electron-stimulated desorption (ESD) experiments in ultrahigh vacuum and by reflection−absorption infrared spectroscopy (RAIRS). The results reveal that Ag(I) carboxylates with aliphatic side chains are particularly favourable for FEBID. Following electron impact ionization, they fragment by loss of volatile CO2. The remaining alkyl radical converts to a stable and equally volatile alkene. The lower decomposition efficiency of Ag(I) benzoate and Ag(I) 3,3-dimethylbutynyl is explained by calculated average local ionization energies (ALIE) which reveal that ionization from the unsaturated carbon units competes with ionization from the coordinate bond to Ag. This can stabilise the ionized complex with respect to fragmentation. This insight provides guidance with respect to the design of novel FEBID precursors.

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Section: Discussionsupporting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Section: Figurementioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition

et al. 2022

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Structural investigation of zinc‐based photoresists with different substituents for high‐resolution lithography

Luo

Liu

et al. 2023

Applied Organom Chemis

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The fineness of the photolithographic pattern depends largely on the composition and structure of the photoresist, and different structures endow metal‐based photoresists with different photon‐absorbing capabilities. Here, we synthesized zinc‐based photoresists with different electron‐effect substituents (amine and bromine) in the ligands and investigated the influence of the ligand groups on the sensitivity and resolution at deep ultraviolet and electron beam. The developed resist patterns exhibit that the sensitivity of the Zn‐based photoresists containing bromine groups (Zn‐PBBA) is nearly seven times higher than the Zn‐based photoresists containing amine groups (Zn‐PABA) at the same resolution under ultraviolet irradiation, which is supported by the density functional theory (DFT) calculations where a smaller HOMO–LUMO gap for Zn‐PBBA is obtained. Analogously, the Zn‐PBBA also showed better sensitivity and resolution than Zn‐PABA at EBL, with a resolution of 70 nm at a dose of 800 mJ cm−2 by characterization with AFM. This work provides an understanding of the efficient structural design of photoresists and future guidance for the development of better‐performing materials.

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Enhanced Solubility of Zirconium Oxo Clusters from Diacetoxyzirconium(IV) Oxide Aqueous Solution as Inorganic Extreme‐Ultraviolet Photoresists

Kataoka

Sue

2022

Eur J Inorg Chem

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Metal oxo clusters have drawn a great deal of attention as the extreme‐ultraviolet (EUV) photoresists. However, industrial implementation in the next‐generation lithography demands further improvements in their sensitivity and resolution. In this study, a zirconium oxo cluster with methacrylate and acetate ligands was synthesized from diacetoxyzirconium(IV) oxide aqueous solution for use as EUV photoresist materials. The obtained Zr oxo cluster, consisting of a Zr core and methacrylate and acetate ligands, was similar in size to Zr6O4(OH)4(methacrylate)12 cluster, but much more soluble in a variety of organic solvents. Open‐frame exposure tests revealed that the Zr oxo cluster served as a negative tone photoresist with a sensitivity greater than that of Zr6O4(OH)4(methacrylate)12 cluster. At a dose of 22 mJ/cm2 in the absence of photoacid generators, the Zr oxo cluster film resolved a pattern 15 nm in width, which is sufficiently low to meet the current technological requirements.

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Role of low-energy electrons in the solubility switch of Zn-based oxocluster photoresist for extreme ultraviolet lithography

Abstract: Electron-induced reactions make an important contribution to the solubility switch of a novel Zn oxocluster resist in extreme ultraviolet lithography (EUVL). The study also gives direct evidence that chain reactions are involved in this process.

Cited by 22 publications

References 34 publications

Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition

Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition

Structural investigation of zinc‐based photoresists with different substituents for high‐resolution lithography

Enhanced Solubility of Zirconium Oxo Clusters from Diacetoxyzirconium(IV) Oxide Aqueous Solution as Inorganic Extreme‐Ultraviolet Photoresists

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