Miscibility Behavior of Poly(4-hydroxystyrene) with Poly(4-acetoxystyrene)

Himuro, Shozo; Sakamoto, Noriyuki; Arichi, Shizuo

doi:10.1295/polymj.24.1371

Cited by 8 publications

(3 citation statements)

References 18 publications

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“…We find that the simulated T g for PtBMA is between 380 and 470 K depending on tacticity, with the observed trend being similar to experimental values of PMMA polymers where the T g decreases going from syndiotactic to atactic to isotactic . We also find that the T g value for atactic PHS homopolymers is ∼450 K (within the experimental range: 410 K–470 K , ) and for atactic alternating copolymers is ∼440 K.…”

Section: Methodssupporting

confidence: 83%

Atomistic Modeling Approach for Predicting Association of Photoacid Generators in Extreme Ultraviolet Polymeric Photoresists

Prajwal,

Blackwell,

Theofanis

et al. 2023

Chem. Mater.

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This work advances a computational framework to probe the molecular inhomogeneities that occur in chemically amplified photoresists intended for ultraviolet (EUV) lithography. Atomistic molecular dynamics simulations were used to probe the effect of ionic and steric interactions on the dispersibility of photoacid generators (PAGs) in the polymer medium before EUV exposure, as poor dispersibility is a potential source of postexposure feature roughness. The PAGs studied include ionic salts containing a triphenyl sulfonium (TPS) cation with trifluoromethane (TFMeS), nonafluorobutane (NFBuS), perfluorophenyl (PFPS), and adamantyltetrafluoroethyl (ATFEtS) sulfonate anions, and a nonionic naphthalimide sulfonate PAG. The model photoresists studied are poly(tert-butyl methacrylate) (PtBMA) and poly(4-hydroxy styrene) (PHS) homopolymers and alternating copolymers thereof. The dissociation free-energy of isolated single and dimer PAGs in the different polymers indicates that PHS segments provide a better solvation environment for ionic PAGs than PtBMA segments and that the nonionic naphthalimide PAG has the highest dispersibility, while TPS-TFMeS solvates better than the bulkier TPS-NFBuS and TPS-ATFEtS salts. The dissociation free-energies were consistent with a trend of increasing PAG clustering in less polar media at high PAG concentrations (7 to 36 wt %), and of increasing dipole moments for PAGs in less polar implicit solvation media as estimated from density functional theory. Both simulations and infrared spectroscopy of the copolymer provide evidence of hydrogen bonded carbonyl groups whose prevalence diminishes upon the addition of ionic PAGs. For TPS-TFMeS loadings between 25 and 29 wt %, our analysis revealed short string-like salt clusters in PHS homopolymer, large globular clusters in PtBMA homopolymer, and a heterogeneous distribution of string-like and globular PAG aggregates in the alternating copolymer. For all PAG loadings, TPS-ATFEtS and TPS-NFBuS PAGs exhibited the highest extent of aggregation. Altogether, the advocated methodology is a potentially effective tool to rank and identify polymer and PAG chemistries with improved compatibility and mixing homogeneity.

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Section: Methodssupporting

confidence: 83%

Atomistic Modeling Approach for Predicting Association of Photoacid Generators in Extreme Ultraviolet Polymeric Photoresists

Prajwal,

Blackwell,

Theofanis

et al. 2023

Chem. Mater.

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“…All samples exhibit single T g s. In addition, the S/AS linear gradient copolymers have T g values similar to the random copolymers of comparable composition (and independent of polymerization method). The T g values in Table are between the T g s of PS (100 °C) and PAS (125 °C) . However, in all cases except for sample lingradB, the T g values are much closer to the T g of PAS.…”

Section: Resultsmentioning

confidence: 78%

Synthesis and Glass Transition Behavior of High Molecular Weight Styrene/4-Acetoxystyene and Styrene/4-Hydroxystyrene Gradient Copolymers Made via Nitroxide-Mediated Controlled Radical Polymerization

et al. 2004

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Styrene (S)/4-acetoxystyrene (AS) gradient copolymers were synthesized by moderate-temperature, nitroxide-mediated controlled radical polymerization. Hydrolysis of styrene/4-acetoxystyrene gradient copolymers produced styrene/4-hydroxystyrene (HS) gradient copolymers. Molecular weight (MW) characterization via gel permeation chromatography demonstrated that these materials were made in a “controlled” manner, while intrinsic viscosity measurements revealed that the MWs exceeded 100 000 g/mol, with apparent viscosity-average MW values ranging between 100 000 and 385 000 g/mol, making these materials the first high MW gradient copolymers ever synthesized. Characterization of the glass transition temperature, T g, revealed different behavior depending on the type of gradient copolymer produced. Using a normal thermal history for measuring T g by differential scanning calorimetry (DSC), linear gradient copolymers exhibited one T g, with a value intermediate to the T gs of polystyrene (PS) and poly(4-acetoxystyrene) (PAS) or poly(4-hydroxystyrene) (PHS). In contrast, “blocky” gradient copolymers with overall S content ≥55 mol % yielded two T gs, one near the T g of PS and the other intermediate to the T gs of PS and PAS or PHS, indicating microphase separation. When the cumulative composition of the “blocky” gradient copolymer was majority AS or HS, only one T g was resolved, with a value near the T g of PAS or PHS. For S/AS and S/HS gradient copolymers of identical chain length, overall fractional S content, and strength of gradient, physical aging at 90 °C provided resolution of a second T g via DSC, allowing comment on how manifestations of microphase separation depend on gradient structure and the strength of the comonomer repulsive interactions.

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“…A number of studies reported the thermal properties of AOST, HOST and tBA monomers using TGA and DSC techniques, and the Tg values were found to vary within a range depending on the polymer molecular weight [360,[383][384][385][386][387][388][389][390]. The ranges of reported Tg values are 112-125 ºC for AOST [383][384][385][386][387][388], 30-50 ºC for tBA [391,392], and 150-190 for HOST [360,[385][386][387][388]390] homopolymer. Though a much broader range of Tg (31-107 ºC) for tBA homopolymer is listed in polymer handbook which is noted as conflicting data [393].…”

Section: Thermal Propertiesmentioning

confidence: 99%

Understanding and controlling the structure of thin polymer films used in photolithography

Alam¹

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Line edge roughness (LER) is one of the major impediments to the semiconductor industry achieving the desired device performance and satisfying the goals set by International Technology Roadmap for Semiconductor (ITRS). LER is defined as any sort of unwanted roughness in semiconductor features, and among many other factors, structural heterogeneity of the photoresist materials is one of the sources of LER in photolithographic devices. This gives the motivation to study a new class of copolymer named 'gradient copolymer', which is unique in terms of the copolymer chain structure. The copolymer composition of gradient copolymers changes from one end of the chain to the other gradually, while the copolymer composition is on average constant along the chains for conventional statistical copolymers. In contrast, block copolymers show an abrupt switch in the polymer composition. In this study, statistical, block and gradient copolymers have been synthesized for two different monomer pairs (styreneacrylonitrile and hydroxystyrene t-butyl acrylate) using reversible addition-fragmentation chain transfer (RAFT) and conventional radical polymerization (CvRP) method, and their surface properties extensively studied.The kinetics of copolymerization of styrene (St) and acrylonitrile (AN) by RAFT method was studied in detail. Reactivity ratios of St and AN were determined for nine different feed compositions for RAFT, and the effect of solvent on reactivity ratios was discussed based on the bootstrap model. Batch polymerization of styrene (St) and acrylonitrile (AN) yielded statistical and spontaneous gradient copolymers depending on the monomer feed ratio, and the chain structures were confirmed from the change in the copolymer composition. St-and AN-centered triad distributions were determined using quantitative 13 C NMR. Using the continuous feeding approach, forced gradient St-AN copolymers were prepared, and St-block-AN copolymers synthesized by the chain extension method. Statistical, gradient and block copolymers have also been synthesized for the acetoxystyrenet-butyl acrylate monomer system. The statistical and gradient structures were confirmed from the change in the composition since this pair does not provide any well resolved peaks for different triad sequences in 13 C NMR. Hydroxystyrenet-butyl acrylate (HOST-tBA) copolymers were prepared by selective hydrolysis of 4-acetoxystyrenet-butyl acrylate (AOST-tBA) copolymers.The properties of the both copolymer systems were found to be strongly dependent on the copolymer structure. A unique broad glass transition was observed for the gradient copolymers, which is different from behaviour of the statistical and block copolymers. Surface properties of St-AN statistical, gradient and block copolymer thin films were found to be very different due to the

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Miscibility Behavior of Poly(4-hydroxystyrene) with Poly(4-acetoxystyrene)

Cited by 8 publications

References 18 publications

Atomistic Modeling Approach for Predicting Association of Photoacid Generators in Extreme Ultraviolet Polymeric Photoresists

Atomistic Modeling Approach for Predicting Association of Photoacid Generators in Extreme Ultraviolet Polymeric Photoresists

Synthesis and Glass Transition Behavior of High Molecular Weight Styrene/4-Acetoxystyene and Styrene/4-Hydroxystyrene Gradient Copolymers Made via Nitroxide-Mediated Controlled Radical Polymerization

Understanding and controlling the structure of thin polymer films used in photolithography

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