Mechanisms of EUV exposure: electrons and holes

Narasimhan, Amrit; Grzeskowiak, Steven; Ackerman, Christian; Flynn, Tracy; Denbeaux, Greg; Brainard, Robert L.

doi:10.1117/12.2258321

Cited by 16 publications

(14 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mechanistic studies of chemically amplified EUV resists show strong evidence for the involvement of both electron trapping and hole-initiated mechanistic pathways for the photolysis of photoacid generators. 22 Therefore, to gain mechanistic insight into the EUV photoreaction of NP1,…”

Section: Electrochemical Studiesmentioning

confidence: 99%

First-row transitional-metal oxalate resists for EUV

Wilklow-Marnell

Moglia

Steimle

2018

J. Micro/Nanolith. MEMS MOEMS

View full text Add to dashboard Cite

We have developed inorganic oxalate compounds ½PPh 3 ðCH 2 PhÞ½Mð2; 2 0-bipyridineÞ n ðoxalateÞ ð3−nÞ (n ¼ 1,2,3;M¼ Co, Fe, Cr) capable of acting as negative-tone extreme ultraviolet (EUV) resists. Two important trends are observed: (1) sensitivity increases with the number of oxalate ligands; (2) Cobalt and iron complexes exhibit greater sensitivity than analogous chromium complexes. Lithographic studies of the most successful compound, ½PPh 3 ðCH 2 PhÞ½Coð2; 2 0-bipyridineÞðoxalateÞ 2 , show that it can consistently achieve 20 nm h/p lines at doses approaching 30 mJ∕cm 2. Infrared, paramagnetic nuclear magnetic resonance, and cyclic voltammetric studies of this compound show that the reaction products of the EUV photochemistry are Co(II)(2,2'-bipyridine) (oxalate) and ½PPh 3 ðCH 2 PhÞ 2 ðoxalateÞ formed from the decomposition of one of the oxalate ligands into two equivalents each of carbon dioxide and electrons.

show abstract

Section: Electrochemical Studiesmentioning

confidence: 99%

First-row transitional-metal oxalate resists for EUV

Wilklow-Marnell

Moglia

Steimle

2018

J. Micro/Nanolith. MEMS MOEMS

View full text Add to dashboard Cite

show abstract

“…The main energy conduit here begins with the resist polymer [4] since it provides the majority of absorption targets for photon interaction with core level electrons -atomic orbital localized, resulting in higher energy primary electron [5]. The initial photon could therefore result in the generation of several secondary electrons at lower energy [6][7][8] that eventually enable chemical modifications, e.g. decomposition of the PAG [9] or bond scission that leads to crosslinking between molecular components.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the role of photons and electrons upon their chemical interaction with photoresist during EUV exposure

Pollentier

Vesters

Petersen

et al. 2018

Advances in Patterning Materials and Processes XXXV

View full text Add to dashboard Cite

The interaction of 91.6 eV EUV photons with photoresist-in particular chemically amplified resist (CAR)-is different than exposure at 193 nm and 248 nm wavelengths. The latter is understood well and it is known that photons interact with electrons in the resist's molecular valence orbitals (for chemically amplified resist (CAR) the photon interacts with the photo acid generator (PAG), which leads to a deprotection reaction on a polymer after a thermal catalytic reaction during a post-exposure-bake.). At EUV however, more steps are involved in the radiolysis process between the absorption of the photon and the final chemical modification. These are related to the generation of primary electrons and their decay to lower energy secondary electrons, and most of this steps are not well understood. In this paper, the reaction products from EUV and low energy electron exposure are examined using Residual Gas Analysis (RGA), which measures and analyzes the outgassing products related to the ongoing reactions. This investigation is applied firstly on a model CAR where details of the resist chemical constituents were known prior to testing. The measurement not only resolved information on the expected acid related reactions from the PAG and protection groups, but also exhibited direct scission reactions of the polymer, where some of them lead to polymerization reactions. Moreover, the measurement quantifies the balance between the different ongoing reactions, which were confirmed by contrast curve measurements. Based on learnings on the model resist, applied the measurement technique to commercial resists, where actual resist chemistry composition is not known. Despite that, it was found that information could be deduced to distinguish between acid related ongoing reactions and direct scission of reaction on the base polymer and quantify their relation. Moreover, different generations of commercial resists based on similar chemistry platform were investigated, which revealed that improvements in printing performance could be explained by PAG reaction yield increase.

show abstract

“…In addition, Thackeray et al [14], Goldfarb et al [18], and Tarutani et al [19] have shown that PAG reduction potential correlates well with EUV clearing dose, E 0 , and acid yield, indicating that PAG electron affinity directly relates to acid production in EUV exposure. Bulk electrolysis of PAGs at their reduction potentials has shown a 1:1 correlation between electrons injected and acid produced, demonstrating acid production through direct electron-PAG interactions at the low energies involved in electrolysis [9]. Furthermore, co-dependent electron trapping and hole-initiated chemistries would require a full 6-10 electron-holes pairs to produce the 5-6 H + observed by acid quantum yield measurements.…”

Section: Reaction Mechanisms In Chemically Amplified Resistsmentioning

confidence: 99%

“…Acid quantum yield measurements using Coumarin-6 in two different polymers with the same PAG have shown acid production even when the hole-initiated pathway is suppressed, such as in the polymer poly-4-methoxystyrene (PMS). Exposures of films of PMS and PAG to 75 keV ebeam and EUV show acid production through protonation of Coumarin-6 via absorbance spectroscopy [9,20].…”

Section: Reaction Mechanisms In Chemically Amplified Resistsmentioning

confidence: 99%

See 1 more Smart Citation

What We Don’t Know About EUV Exposure Mechanisms

Narasimhan

Wisehart

Grzeskowiak

et al. 2017

J. Photopol. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

The lithography community has studied EUV photoresists for nearly thirty years. Yet, some of the most basic details of the interaction of EUV photons with photoresists remain poorly understood. In a typical photochemical reaction using long-wavelength light ( = 157-1000 nm), photons create excited states in photoactive compounds, thereby creating known quantities of intermediates and photoproducts at measurable rates.The photochemical reactions occurring during EUV exposure are much more complex and, as yet, not fully explored. The 92 eV EUV photons ionize molecules in the resist, creating holes and free electrons, however, the numbers of these electrons created, their reaction mechanisms, lifetimes and reaction cross-sections are not well known. Here, we will discuss experimental results and provide insight into these poorly understood aspects of EUV exposure mechanisms.

show abstract

Mechanisms of EUV exposure: electrons and holes

Cited by 16 publications

References 11 publications

First-row transitional-metal oxalate resists for EUV

First-row transitional-metal oxalate resists for EUV

Unraveling the role of photons and electrons upon their chemical interaction with photoresist during EUV exposure

What We Don’t Know About EUV Exposure Mechanisms

Contact Info

Product

Resources

About