Electron and Hole Transfer in Anion-Bound Chemically Amplified Resists Used in Extreme Ultraviolet Lithography

Komuro, Yoshitaka; Yamamoto, Hiroki; Utsumi, Yoshiyuki; Ohomori, Katsumi; Kozawa, Takahiro

doi:10.7567/apex.6.014001

Cited by 11 publications

(19 citation statements)

References 28 publications

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“…Radicals are generated by charge-transfer reactions on functional units. Pulse radiolysis has been instrumental to track radiation-induced intermediates in different kinds of resist. ,,, It can detect the intermediates formed and decayed in the nanosecond range during the irradiation with a high-energy electron beam. Also, high-energy long exposure by γ rays in a controlled reaction system (as defined in Materials and Methods ), followed by HPLC is useful to detect radiolytic products.…”

Section: Resultsmentioning

confidence: 99%

Extreme Ultraviolet Lithographic Performance and Reaction Mechanism of Polymeric Resist─Utilizing Radical- and Acid-Amplified Cross-Linking

Naqvi,

Enomoto,

Machida

et al. 2024

Chem. Mater.

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Extreme ultraviolet (EUV) lithography is a promising technology for making chips beyond 7 nm technology node; however, it comes with its own challenges. One of them is the need to find a suitable EUV resist. Photoresist performance is gauged by the resolution, LER, and sensitivity trade-off. However, the primary challenge for the photoresist in EUV lithography is the major shift in reaction chemistry relative to that in deep ultraviolet (DUV) lithography. The interaction of the EUV photon (92 eV) with the widely used conventional chemically amplified resist (CAR) is different than that of the DUV photon (5−6 eV). The DUV photon excites only the valence electrons of the photo-acid generator in CAR, which results into acid generation. However, a high-energy EUV photon can ionize the CAR polymer matrix. This leads to the generation of a cascade of secondary electrons. Thus, in addition to acid generation, other chemical reactions like bond scission and cross-linking occur by the interactions between resist and secondary electrons. Apart from chemically amplified reactions, CARs are not very efficient at utilizing the additional pathways offered by secondary electrons. Moreover, stochastics, arising from photon and chemical shot noise, are an additional challenge for an EUV resist. Therefore, there is a need for an alternative photoresist to CAR. Herein, we report a single polymer chain negative tone photoresist. The resist has an acid generator, an organotin moiety, and an acid reactive unit attached to a polymer chain. The resist is designed to use EUV-generated secondary electrons to generate acid and polymer-bound radicals. The polymer-bound radicals and acid amplification reaction can induce cross-linking among polymer chains to create a negative tone solubility switch. In this study, the EUV printability study and reaction mechanism of the resist are elucidated. Electron transfer reactions for radical generation were studied with the help of nanosecond pulse radiolysis and γ-radiolysis. Liquid chromatography and mass spectrometry were used to identify possible acid-amplified reactions.

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Section: Resultsmentioning

confidence: 99%

Extreme Ultraviolet Lithographic Performance and Reaction Mechanism of Polymeric Resist─Utilizing Radical- and Acid-Amplified Cross-Linking

Naqvi,

Enomoto,

Machida

et al. 2024

Chem. Mater.

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“…Pulse radiolysis, a time-resolved spectroscopic method used for ionized resist polymers such as novolaks [6,7], acrylates [8][9][10], and polyoxystyrenes [11][12][13][14][15][16], has been used to model base polymers of CARs. Pulse radiolysis studies of resist polymers have been conducted mainly in dilute solution.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of radical cations of poly(4-hydroxystyrene) in the presence and absence of triphenylsulfonium triflate as determined by pulse radiolysis of its highly concentrated solution

Okamoto

Ishida

Yamamoto

et al. 2016

Chemical Physics Letters

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Pulse radiolysis of highly concentrated poly(4-hydroxystyrene) (PHS) solutions in cyclohexanone and p-dioxane was performed both with and without an onium-type photoacid generator (PAG). With increasing PHS concentration, the rate constant of deprotonation of PHS radical cations was found to decrease. In the presence of PAG, the yield of the multimer radical cation of PHS was shown to decrease. We found that pairing between the anions produced by the attachment of dissociative electrons of PAGs and the monomer PHS radical cations restrict local molecular motions, leading to the formation of the multimer PHS radical cations.

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“…We have investigated the mechanism of acid generation induced in ABPs by secondary electrons, considering that the mechanism is another reason for the low sensitivity. 19,20) The chemical reactions induced in ABP films were investigated with the electron pulse, γ and EUV radiolyses. The kinetics in ABPs was investigated by the electron pulse radiolysis of ABP solutions.…”

Section: Introductionmentioning

confidence: 99%

Modeling and simulation of acid generation in anion-bound chemically amplified resists used for extreme ultraviolet lithography

Komuro

Kawana

Hirayama

et al. 2015

Jpn. J. Appl. Phys.

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Extreme ultraviolet (EUV) lithography is the most promising candidate technique for the high-volume production of semiconductor devices with half-pitches of sub-10 nm. An anion-bound polymer, in which the anion part of onium salts is polymerized, has attracted much attention from the viewpoint of the control of acid diffusion. In this study, we modeled the acid generation processes in the anion-bound chemically amplified resists upon exposure to EUV radiation and developed a Monte Carlo simulation code. Using the developed simulation code, the dependence of the quantum efficiency of acid generation on the concentration of acid generator units was calculated. The calculated quantum efficiencies well agreed with the experimental values with a fitting error of less than 10%. The thermalization distance was considered to be approximately 3 nm. The blur of proton distribution intrinsic to the reaction mechanisms of anion-bound chemically amplified resists was roughly estimated to be 4.5–6.5 nm.

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Electron and Hole Transfer in Anion-Bound Chemically Amplified Resists Used in Extreme Ultraviolet Lithography

Cited by 11 publications

References 28 publications

Extreme Ultraviolet Lithographic Performance and Reaction Mechanism of Polymeric Resist─Utilizing Radical- and Acid-Amplified Cross-Linking

Extreme Ultraviolet Lithographic Performance and Reaction Mechanism of Polymeric Resist─Utilizing Radical- and Acid-Amplified Cross-Linking

Dynamics of radical cations of poly(4-hydroxystyrene) in the presence and absence of triphenylsulfonium triflate as determined by pulse radiolysis of its highly concentrated solution

Modeling and simulation of acid generation in anion-bound chemically amplified resists used for extreme ultraviolet lithography

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