Resolution, Line-Edge Roughness, Sensitivity Tradeoff, and Quantum Yield of High Photo Acid Generator Resists for Extreme Ultraviolet Lithography

Higgins, Craig; Szmanda, Charles R.; Antohe, Alin; Denbeaux, Greg; Georger, Jacque H.; Brainard, Robert L.

doi:10.7567/jjap.50.036504

Cited by 30 publications

(38 citation statements)

References 25 publications

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“…Previous work done with EUV photons within our research group demonstrated the same trend for increasing PAG concentration. 9 An unaffiliated group has also seen the same trends with EUV exposures in terms of increasing PAG concentration. 3 Studying the concentration effects for an assortment of structures may provide insight into maximizing the number of reactions for a particular PAG-polymer combination, and future work is ongoing.…”

Section: Pag Concentration Effectsmentioning

confidence: 54%

“…Prior work done with EUV photons demonstrated the same trend. 3,9 Future work will entail the study of a larger variety of PAG molecules, as well as the study of electron chemistry in exotic non-chemically amplified photoresists. The PAG molecules studied in this article will be revisited for electron energies below 80 eV once this capability is installed in ERIC.…”

Section: Discussionmentioning

confidence: 99%

“…The number density is based on the known formulation conditions of the samples, and using a value of 1.2 g/cm 3 for the assumed total film density. 8,9 Uniform PAG density is assumed throughout the thickness of the photoresist. 8 The number of PAG reactions per incident electron (R/Φ) is measured from the previously described experiment.…”

Section: Electron Cross Sectionmentioning

confidence: 99%

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Cross sections of EUV PAGs: influence of concentration, electron energy, and structure

et al. 2016

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Optimizing the photochemistry of extreme ultraviolet (EUV) photoresists should provide faster, more efficient resists which would lead to greater throughput in manufacturing. The fundamental reaction mechanisms in EUV resists are believed to be due to interactions with energetic electrons liberated by ionization. Identifying the likelihood (or cross section) of how these photoelectrons interact with resist components is critical to optimizing the performance of EUV resists. Chemically amplified resists utilize photoacid generators (PAGs) to improve sensitivity; measuring the cross section of electron induced decomposition of different PAGs will provide insight into developing new resist materials.To study the interactions of photoelectrons generated by EUV absorption, photoresists were exposed to electron beams at energies between 80 and 250 eV. The reactions between PAG molecules and electrons were measured using a mass spectrometer to monitor the levels of small molecules produced by PAG decomposition that outgassed from the film. Comparing the cross sections of a variety of PAG molecules can provide insight into the relationship between chemical structure and reactivity to the electrons in their environments. This research is a part of a larger SEMATECH research program to understand the fundamentals of resist exposures to help in the development of new, better performing EUV resists.

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Section: Pag Concentration Effectsmentioning

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Section: Electron Cross Sectionmentioning

confidence: 99%

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Cross sections of EUV PAGs: influence of concentration, electron energy, and structure

et al. 2016

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“…For chemically amplified photoresists, increasing film quantum yield will improve sensitivity (decrease E size ) and consequently impair LER [8][9][10]. This improved sensitivity allows for higher base concentrations, and LER will improve with increasing base concentrations resulting in a lower Z-parameter [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…This is commonly known as the RLS tradeoff, which is quantified by the Z-parameter (Eq. 1) in order to directly compare photoresist performance [8][9][10]. A lower Z-parameter suggests that the photoresist is superior, and is defined as 3 2 size…”

Section: Introductionmentioning

confidence: 99%

Acid Generation Efficiency of EUV PAGs via Low Energy Electron Exposure

Grzeskowiak

Narasimhan

Rebeyev

et al. 2016

J. Photopol. Sci. Technol.

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Optimizing the photochemistry of extreme ultraviolet (EUV) photoresists can lead to faster, more efficient resists needed for implementation of EUV lithography into high volume manufacturing. EUV photoresists must simultaneously meet three requirements: improved resolution, low line edge roughness (LER), and high sensitivity. Common EUV photoresists utilize photoacid generators (PAGs) to improve sensitivity, which is affected by many variables, such as developer choice, developer concentration, PAG quantum yield, etc. Isolating one of these parameters will aid in the optimization of sensitivity. Prior work using alternate methods shows it is possible for resists to generate 5-6 acids per absorbed photon. However, the energy of the weakest bond in a typical PAG molecule is on the order of a few electron volts, it should be possible to reach much higher quantum yields with EUV (92 eV) photons. The photochemistry in EUV lithography is believed to be dominated by the energetic electrons generated from ionization. Investigating the acid generation efficiency for a variety of PAGs and concentrations upon electron exposure may lead to the development of resists with higher quantum yield, improving current EUV photoresist platforms. In this study, the reactions between PAG molecules and electrons were measured by using a mass spectrometer to monitor the levels of small molecules produced by PAG decomposition that outgassed from the film.

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Extreme UV Resist Exhibiting Synergism between Chemical and Physical Crosslinking Mechanisms

Kim

et al. 2023

Langmuir

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Carbon–fluorine bonds in fluorinated molecules can undergo homolytic cleavage reactions when electrons are injected, and the resulting radicals combine to form network structures characterized by reduced solubility. This crosslinking chemistry suggests a new category of patterning materials that function under electron beam (e-beam) and extreme ultraviolet (EUV) lithographic conditions. Although this chemistry enables the production of 50 nm or smaller-sized features of simple fluoroalkylated polymers, it is limited by the need for relatively large amounts of irradiation energy to achieve required solubility changes. Therefore, this study was undertaken to devise a sensitivity-enhancing strategy based on a synergistic combination of radical crosslinking and hydrogen-bonding interactions between highly fluoroalkylated copolymers. An alternating copolymer was synthesized using tert-butoxystyrene and a fluoroalkylated maleimide, the former of which produces active hydrogens through catalytic acidolysis reactions. When the polymer was blended with a catalytic amount of a photoacid generator and subjected to lithographic patterning tests under e-beam and EUV irradiation, the deprotection reactions of tert-butoxy moieties proceeded at room temperature and led to a solubility decrease. We presume the small number of hydroxyl moieties produced formed an intermolecular hydrogen-bonding network, which acted synergistically with the covalent crosslinks generated by C–F bonds. When 30 nm features of copolymer thin films were fabricated by EUV lithography, sensitivity was improved by 25–34% without significant deterioration of pattern quality, especially line-edge roughness. These results demonstrate that EUV resists with improved patterning capabilities can be achieved by combining catalytic acidolysis reactions and noncatalytic crosslinking chemistry.

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Resolution, Line-Edge Roughness, Sensitivity Tradeoff, and Quantum Yield of High Photo Acid Generator Resists for Extreme Ultraviolet Lithography

Cited by 30 publications

References 25 publications

Cross sections of EUV PAGs: influence of concentration, electron energy, and structure

Cross sections of EUV PAGs: influence of concentration, electron energy, and structure

Acid Generation Efficiency of EUV PAGs via Low Energy Electron Exposure

Extreme UV Resist Exhibiting Synergism between Chemical and Physical Crosslinking Mechanisms

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