A comparison of the reaction-diffusion kinetics between model-EUV polymer and molecular-glass photoresists

Kang, Shuhui; Lavery, Kristopher A.; Choi, Kwok Pui; Prabhu, Vivek M.; Wu, Wen‐Li; Lin, Eric K.; Silva, Anuja De; Felix, Nelson; Ober, Christopher K.

doi:10.1117/12.773018

Cited by 13 publications

(17 citation statements)

References 14 publications

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“…The L d may be estimated without neutron refl ectivity, [ 46,47 ] however, the shape of the profi le is critical, in particular, as the feature size approach the diffusion length. This is the ultimate challenge in photoresists and the effect is controlled by the polymer chemistry as shown next.…”

Section: Photoacid Generator Size Effectmentioning

confidence: 99%

Photoresist Latent and Developer Images as Probed by Neutron Reflectivity Methods

Prabhu¹,

Kang²,

VanderHart³

et al. 2010

Advanced Materials

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Photoresist materials enable the fabrication of advanced integrated circuits with ever-decreasing feature sizes. As next-generation light sources are developed, using extreme ultraviolet light of wavelength 13.5 nm, these highly tuned formulations must meet strict image-fidelity criteria to maintain the expected performance gains from decreases in feature size. However, polymer photoresists appear to be reaching resolution limits and advancements in measurements of the in situ formed solid/solid and solid/liquid interface is necessary. This Review focuses on the chemical and physical structure of chemically amplified photoresists at the lithographic feature edge at length scales between 1 nm and 100 nm. Neutron reflectivity measurements provide insight into the nanometer-scale composition profiling of the chemical latent image at an ideal lithographic line-edge that separates optical resolution effects from materials processing effects. Four generations of advanced photoresist formulations were examined over the course of seven years to quantify photoresist/photoacid and photoresist/developer interactions on the fidelity of lithographic features. The outcome of these measurements complement traditional resist design criteria by providing the effects of the impacts of the photoresist and processing on the feature fidelity. These physical relations are also described in the context of novel resist architectures under consideration for next-generation photolithography with extreme-ultraviolet radiation.

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Section: Photoacid Generator Size Effectmentioning

confidence: 99%

Photoresist Latent and Developer Images as Probed by Neutron Reflectivity Methods

Prabhu¹,

Kang²,

VanderHart³

et al. 2010

Advanced Materials

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“…It was proposed that this enhancement, which is observed in several CAR resins with volatile protecting groups, arises from a short-lived increase in free volume upon reaction. ,,− However, this concept is inconsistent with measurements of PBOCSt deprotection, which show the same timescales for reaction and polymer densification . Another common approach in reaction–diffusion models is the inclusion of additional processes describing an acid loss. ,, Acid loss is often presented as a “trapping process” attributed to either contaminants or strong local interactions with the polymer, such as hydrogen bonding, and has been used in models of several CAR chemistries. ,,,− …”

Section: Introductionmentioning

confidence: 99%

Ion Diffusion in Chemically Amplified Resists

et al. 2021

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The acid-catalyzed deprotection of glassy polymer resins is an important process in semiconductor lithography. Studies have shown that the reaction kinetics in these materials is controlled by slow diffusion of the acid−anion catalyst, but trends deviate from models of a first-order reaction coupled to a composition-invariant Fickian diffusivity. We present a concerted experimental and computational effort to examine catalyst diffusion in a model resin of poly(4-hydroxystyrene-co-tert-butyl acrylate-co-styrene), or P-(HOSt-tBA-St), which is deprotected in the presence of an acid catalyst to poly(4-hydroxystyrene-co-acrylic acid-co-styrene), or P(HOSt-AA-St). We employed an inert catalyst analogue to examine long-time ion dynamics in both terpolymers with atomistic molecular dynamics simulations and compared the calculated Fickian diffusivities with direct measurements of ion diffusion fronts using time-of-flight secondary ion mass spectrometry. Our results demonstrate that ion diffusivities in P(HOSt-tBA-St) and in P(HOSt-AA-St) are similar near and below the glass transition, consistent with a diffusion process that is dominated by interactions with the polar HOSt units. We then compared the bulk reaction kinetics measured by Fourier-transform infrared spectroscopy with reaction kinetics obtained using mesoscopic reaction−diffusion models. We found that initial reaction kinetics is significantly accelerated compared to predictions based on the long-time ion diffusivities of our inert system. This study highlights the potential of atomistic modeling coupled with targeted experiments for interrogating the physical and chemical processes that control pattern formation in next-generation lithographic materials.

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“…A key aim for the development of photoresists and associated processes is to simultaneously improve RLS. Many gains can be made by optimisation of resist formulations, although more disruptive technologies include the redesign of the resists and such approaches include: polymer bound PAG resists, [1][2][3][4][5][6][7] molecular glass resists [8][9][10][11][12][13][14][15][16] and chain scissioning resists. [17][18][19][20][21][22][23][24][25][26] In particular, polymer bound PAG resists have achieved a great deal of success as EUVL platforms, although improvements are still required for achieving the ITRS goals.…”

Section: Introductionmentioning

confidence: 99%

Extending the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly

et al. 2014

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Directed self-assembly (DSA) is a promising technique for extending conventional lithographic techniques by being able to print features with critical dimensions under 10 nm. The most widely studied block copolymer system is polystyreneblock-polymethyl methacrylate (PS-b-PMMA). The system is well understood in terms of its synthesis, properties and performance in DSA. However, PS-b-PMMA also has a number of limitations that impact on its performance and hence scope of application. The primary limitation is the low Flory-Huggins polymer-polymer interaction parameter (χ), which limits the size of features that can be printed by DSA. Another issue with block copolymers in general is that specific molecular weights need to be synthesized to achieve desired morphologies and feature sizes. We are exploring blending ionic liquid additiveswithPS-b-PMMAto increase the χ parameter. This allows smaller feature sizes to be accessed by PS-b-PMMA. Depending on the amount of additive it is also possible to tune the domain size and the morphology of the systems. These findings may expand the scope of PS-b-PMMA for DSA.

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A comparison of the reaction-diffusion kinetics between model-EUV polymer and molecular-glass photoresists

Cited by 13 publications

References 14 publications

Photoresist Latent and Developer Images as Probed by Neutron Reflectivity Methods

Photoresist Latent and Developer Images as Probed by Neutron Reflectivity Methods

Ion Diffusion in Chemically Amplified Resists

Extending the scope of poly(styrene)-block-poly(methyl methacrylate) for directed self-assembly

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