Structural modification of poly (methyl methacrylate) due to electron irradiation

Tiwari, Pragya; Srivastava, Arvind K.; Khattak, B. Q.; Verma, Suveer; Upadhyay, Anand; Sinha, A. K.; Ganguli, Tapas; Lodha, G. S.; Deb, S. K.

doi:10.1016/j.measurement.2014.01.017

Cited by 21 publications

(14 citation statements)

References 14 publications

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“…Moreover, when ZEP and PMMA were compared, the higher etch resistance of ZEP observed was attributed to the a-methylstyrene moiety. 15 As reported in our previous paper, the etch durability of SML is very similar to that of the ZEP resist 8 and can be attributed to the presence of the a-methylstyrene group, as revealed by the FTIR analysis of SML, and its effect on the lithographic performance.…”

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confidence: 72%

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Correlation of lithographic performance of the electron beam resists SML and ZEP with their chemical structure

Gangnaik

Georgiev

Holmes

2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Study of topographical and structural changes occurring in a positive resist known as SML after electron beam lithography are presented in this article. The authors also defined its chemical structure, which is very important for understanding the lithographic performance of the resist. The structural and lithographic properties of SML have been compared to the traditional ZEP resist. First, the change in the surface roughness with respect to the electron dose of SML and ZEP resists was measured. It was found that both resists start off with similar initial roughness values. However, ZEP was observed to have a higher roughness at the apex electron dose, thereafter a reduction in roughness was observed. The roughness variation in the two resists reflected on the resolution of the gratings that were patterned in both the resists. Gratings in SML showed smoother line edge roughness, and the patterns transferred using SML resist showed more even features than the ones transferred with ZEP. Subsequently, to understand the chemical composition of the new resist, Fourier transform infrared spectroscopy (FTIR) measurements were performed on both the resists as well as on poly(methyl methacrylate) (PMMA) and their spectra were compared. The FTIR spectra revealed that SML had a chemical structure similar to ZEP and PMMA polymers. The high sensitivity of ZEP is attributed to the Cl group in the compound, which is not present in SML and PMMA and can therefore explain their lower sensitivity to electron exposure in comparison to ZEP. Unlike PMMA but comparable to ZEP, SML shows an IR peak at a wavenumber close to 850 cm−1, suggesting the presence of α-methylstyrene group within its chemical structure, which accounts for the resist's high etch durability, similar to ZEP. Additional FTIR measurements of pre- and postexposed resists together with their attributions to the resolution of the SML and ZEP resists is also demonstrated in this article. The data presented in the study highlights the chemical properties of SML and ZEP resists polymers and correlates them to their lithographic performance

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confidence: 72%

“…In a recent FTIR study of PMMA, to understand the reaction mechanism after e-beam irradiation, it was found that an increase in the C¼C bonds along with the increase in the e-beam dose led to the main chain scission of the PMMA polymer chains. 15 Breaking of the carbonyl group in the polymer was also reported after ebeam radiation. Since the spectra in Fig.…”

mentioning

confidence: 93%

Correlation of lithographic performance of the electron beam resists SML and ZEP with their chemical structure

Gangnaik

Georgiev

Holmes

2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…The different reactions of PMMA and PS to electron irradiation have been discussed in the literature for a long time. Scission of the polymer chains into smaller molecules is the primary process occurring in PMMA, whereas in PS, cross-link formation between the polymer chains is predominant. ,− It is notable that the diameters measured by SEM are less than those measured by DLS (given in Table )for the PTFE–PS particles, this difference is typically within the amount expected due to the difference between hydrodynamic and “dry” diameters. For the PTFE–PMMA particles, however, this difference is considerably larger.…”

Section: Resultsmentioning

confidence: 93%

“…The difference in diameter between DLS and SEM measurements is notably greater for the PMMA-coated particles, which may be partially explained by a combination of swelling of the PMMA due to absorbed water, and the difference in hydrophilicity of the materials resulting in a larger hydrodynamic diameter for the PMMA-coated particles with respect to the PS-coated particles. A more significant factor in this difference in behavior may be due to the PMMA shell shrinking under electron irradiation; PMMA is a well-known positive photoresist for both photolithography and electron beam lithography . Conversely, PS is a negative photoresist and can be expected to be more dimensionally stable under electron beam irradiation .…”

Section: Resultsmentioning

confidence: 99%

“…A more significant factor in this difference in behavior may be due to the PMMA shell shrinking under electron irradiation; PMMA is a well-known positive photoresist for both photolithography and electron beam lithography. 41 Conversely, PS is a negative photoresist and can be expected to be more dimensionally stable under electron beam irradiation. 42 It is also possible that the larger sizes are due to polydispersity in the nanoparticle populations, possibly as a result of low levels of aggregates.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Surface-Energy Control and Characterization of Nanoparticle Coatings

et al. 2020

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Accurate and reproducible measurement of the structure and properties of high-value nanoparticles is extremely important for their commercialization. A significant proportion of engineered nanoparticle systems consist of some form of nominally core–shell structure, whether by design or unintentionally. Often, these do not form an ideal core–shell structure, with typical deviations including polydispersity of the core or shell, uneven or incomplete shells, noncentral cores, and others. Such systems may be created with or without intent, and in either case an understanding of the conditions for formation of such particles is desirable. Precise determination of the structure, composition, size, and shell thickness of such particles can prove challenging without the use of a suitable range of characterization techniques. Here, the authors present two such polymer core–shell nanoparticle systems, consisting of polytetrafluoroethylene cores coated with a range of thicknesses of either polymethylmethacrylate or polystyrene. By consideration of surface energy, it is shown that these particles are expected to possess distinctly differing coating structures, with the polystyrene coating being incomplete. A comprehensive characterization of these systems is demonstrated, using a selection of complementary techniques including scanning electron microscopy, scanning transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, differential centrifugal sedimentation, and X-ray photoelectron spectroscopy. By combining the results provided by these techniques, it is possible to achieve superior characterization and understanding of the particle structure than could be obtained by considering results separately.

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Effect of neutron irradiation on the optical properties of PMMA/RhB used in optical fiber amplification

Nafee

Hamdalla

2019

J Radioanal Nucl Chem

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Structural modification of poly (methyl methacrylate) due to electron irradiation

Cited by 21 publications

References 14 publications

Correlation of lithographic performance of the electron beam resists SML and ZEP with their chemical structure

Correlation of lithographic performance of the electron beam resists SML and ZEP with their chemical structure

Surface-Energy Control and Characterization of Nanoparticle Coatings

Effect of neutron irradiation on the optical properties of PMMA/RhB used in optical fiber amplification

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