Fundamental Studies on the Acid Generator to Improve the Resolution, Line Width Roughness, and Sensitivity Tradeoff under Ionizing Radiation

Utsumi, Yoshiyuki; Irie, Makiko; Komuro, Yoshitaka; Matsuzawa, Kensuke; Hada, Hideo; Haga, Takashi; Ogawa, Satoshi

doi:10.1143/jjap.49.06gf03

Cited by 5 publications

(4 citation statements)

References 23 publications

(30 reference statements)

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“…However, literature data reporting combined EA and Ep values together with openly disclosed PAG structures is scarce [30]. In order to compare the calculated EA and measured Ep from this work to literature data, reported experimental PAG reduction potential data was gathered wherever the PAG chemical structures were disclosed.…”

Section: Pag Electron Affinity / Reduction Potential -Comparative Resmentioning

confidence: 99%

Acid generation efficiency: EUV photons versus photoelectrons

Goldfarb¹,

Afzali-Ardakani²,

Glodde³

2016

SPIE Proceedings

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EUV photoacid generation efficiency has been described primarily in terms of the EUV photon absorption by the PAG or the resist matrix and the production of low energy photoelectrons, which are reported as being ultimately responsible for the high quantum efficiencies reported in EUV resists (>1). Such observation led to a number of recent studies on PAGs with variable electron affinity (EA) and reduction potential (Ered) presumably conducive to a differential EUV photoelectron harvesting efficiency. However, such studies either did not disclose the PAG chemical structures, replaced the EUV source with an e-beam source, or lacked a fundamental discussion of the underlying physical mechanisms behind EUV PAG decomposition. In this work, we report the EUV photospeed of a methacrylatebased resist formulated with a battery of openly disclosed isostructural sulfonium PAGs covering a wide range of EA's and Ered's, to unveil any preferential photoelectron scavenging effect. In parallel, several iodonium PAGs are also tested in order to compare the direct EUV photon absorption route to the photoelectron-based decomposition path. Contrarily to what has been widely reported, we have found no direct correlation whatsoever between photospeed and the calculated EA's or experimental Ered's for the isostructural sulfonium PAGs studied. Instead, we found that iodonium PAGs make more efficient use of the available EUV power due to their higher photoabsorption cross-section. Additionally, we determined a cation size effect for both PAG groups, which is able to further modulate the acid generation efficiency. Finally, we present a formal explanation for the unselective response towards photoelectron harvesting based on the stabilization of the PAG cation by bulky substituent groups, the spatial and temporal range of the transient photoelectron and the differences in electron transfer processes for the different systems studied.

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Section: Pag Electron Affinity / Reduction Potential -Comparative Resmentioning

confidence: 99%

Acid generation efficiency: EUV photons versus photoelectrons

Goldfarb¹,

Afzali-Ardakani²,

Glodde³

2016

SPIE Proceedings

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“…[15][16][17][18][19][20] The reduction potential and EA have been assumed to affect the reactivity of a PAG and electrons. Molecular orbital calculations using the molecular orbital theory [21][22][23][24][25][26] and density functional theory (DFT) [27][28][29][30] have been employed previously to predict these characteristics of PAG. In addition, calculated values have been compared with experimental results, such as the acid yield, 20,22,23) Dill C parameter, 24) and resist sensitivity, 25,27) and a positive correlation has been observed.…”

Section: Introductionmentioning

confidence: 99%

Estimation of electron affinity of photoacid generators: density functional theory calculations using static and dynamic models

Okamoto¹,

Kozawa²

2021

Jpn. J. Appl. Phys.

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The electron affinity (EA) of a photoacid generator (PAG) is an important parameter for estimating the acid generation efficiency in a chemically amplified resist upon exposure to ionizing radiation such as EUV light and an electron beam because the electron attachment of PAG induces PAG decomposition and acid generation. In this study, EAs of ionic and non-ionic PAGs were estimated by density functional theory calculations using static and dynamic models. The former model indicated that radical anions are produced without changing the PAG structure even after electron attachment. The latter model indicated that the product structures are relaxed to their stable structures after electron attachment (dissociative electron attachment). By demonstrating the relationship between the EA and acid yield, the most preferable model was revealed.

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“…In these cases, generally, the acid generation efficiency depends on the reduction potential of the cation structure. 29,30) Therefore, Polymers 2-5 should also have almost the same acid generation efficiency but the acid generation efficiencies of polymer-bound PAGs are about 10% lower than those of the film state. The difference in the acid generation efficiency of polymer-bound PAGs and polymer-blend PAGs is considered to be caused by the difference in energy stabilization with these polymer components.…”

Section: Acid Generation Efficiencymentioning

confidence: 99%

Study of Interrelation Between Reaction of Polymer-Bound/Blend Photoacid Generator with Solvated Electron and Acid Generation Efficiency

Enomoto¹,

Nguyen²,

Tagawa³

2013

Jpn. J. Appl. Phys.

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Polymer-bound photoacid generators (PAGs) (anion bound) and their corresponding polymers were synthesized for evaluation of the reactivity of polymer-bound PAGs with secondary electrons in solutions by the electron beam pulse radiolysis method. In the solutions, the rate constants of polymer-bound PAGs are much lower than those of polymer-blend PAGs. In addition, we evaluated the acid generation efficiencies of polymer-bound PAGs. As a result, despite the film state, the acid generation efficiency of polymer-bound PAGs are about 10% lower than those of the polymer-blend PAGs. These differences are explained by the difference in stabilization effects between polymer-bound PAGs and polymer-blend PAGs in both solutions and films.

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Fundamental Studies on the Acid Generator to Improve the Resolution, Line Width Roughness, and Sensitivity Tradeoff under Ionizing Radiation

Cited by 5 publications

References 23 publications

Acid generation efficiency: EUV photons versus photoelectrons

Acid generation efficiency: EUV photons versus photoelectrons

Estimation of electron affinity of photoacid generators: density functional theory calculations using static and dynamic models

Study of Interrelation Between Reaction of Polymer-Bound/Blend Photoacid Generator with Solvated Electron and Acid Generation Efficiency

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