Kinetics of directed self-assembly of block copolymers on chemically patterned substrates

Müller, Marcus; Li, Weihua; Rey, Juan Carlos Orozco; Welling, Ulrich

doi:10.1088/1742-6596/640/1/012010

Cited by 15 publications

(14 citation statements)

References 46 publications

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“…On the basis of previous studies, , these fully aligned lamellar domains should never relapse to a defective state due to the large difference in free energy between the aligned and nonaligned states, and these grains will gradually grow until defects are annihilated. The initially independent development of registered structures at the bottom and randomly oriented structures at the top was similar to the simulations results by Edwards et al and Müller et al , However, the stitch morphology was not observed in those studies, possibly because they used 1:1 DSA instead of the 3:1 pattern multiplication in this work.…”

Section: Resultssupporting

confidence: 90%

Engineering the Kinetics of Directed Self-Assembly of Block Copolymers toward Fast and Defect-Free Assembly

Ren

Zhou

Chen

et al. 2018

ACS Appl. Mater. Interfaces

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Directed self-assembly (DSA) of block copolymers (BCPs) can achieve perfectly aligned structures at thermodynamic equilibrium, but the self-assembling morphology can become kinetically trapped in defective states. Understanding and optimizing the kinetic pathway toward domain alignment is crucial for enhancing process throughput and lowering defectivity to levels required for semiconductor manufacturing, but there is a dearth of experimental, three-dimensional studies of the kinetic pathways in DSA. Here, we combined arrested annealing and TEM tomography to probe the kinetics and structural evolution in the chemoepitaxy DSA of PS- b-PMMA with density multiplication. During the initial stages of annealing, BCP domains developed independently at first, with aligned structures at the template interface and randomly oriented domains at the top surface. As the grains coarsened, the assembly became cooperative throughout the film thickness, and a metastable stitch morphology was formed, representing a kinetic barrier. The stitch morphology had a three-dimensional structure consisting of both perpendicular and parallel lamellae. On the basis of the mechanistic information, we studied the effect of key design parameters on the kinetics and evolution of structures in DSA. Three types of structural evolutions were observed at different film thicknesses: (1) immediate alignment and fast assembly when thickness < L ( L = BCP natural periodicity); (2) formation of stitch morphology for 1.25-1.45 L; (3) fingerprint formation when thickness >1.64 L. We found that the DSA kinetics can be significantly improved by avoiding the formation of the metastable stitch morphology. Increasing template topography also enhanced the kinetics by increasing the PMMA guiding surface area. A combination of 0.75 L BCP thickness and 0.50 L template topography achieved perfect alignment over 100 times faster than the baseline process. This research demonstrates that an improved understanding of the evolution of structures during DSA can significantly improve the DSA process.

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Section: Resultssupporting

confidence: 90%

Engineering the Kinetics of Directed Self-Assembly of Block Copolymers toward Fast and Defect-Free Assembly

Ren

Zhou

Chen

et al. 2018

ACS Appl. Mater. Interfaces

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“…To confirm this point, we perform the SCMF simulations to estimate the lifetime t f of D1 and D2 defects as a function of χ N . t f in units of the relaxation time τ = R g 0 2 / D , where D and R g 0 are the diffusion constant and the radius of gyration of an undisturbed particle-based polymer chain with N segments in the disordered melt, respectively, is estimated with eight independent samples by simulation as shown in Figure c. , Since the lifetime of a defect is protracted by its free-energy barrier, t f ∝ τ exp(Δ F b / k B T ) with Δ F b / k B T = b 2 ρ 0 L z Δ F ̃ b , it increases rapidly with χ N . , The plot of ln( t f /τ) with respect to Δ F b / k B T in the inset of Figure c shows an approximate linear relationship. Obviously, the annihilating process of D2 of AB 2 is significantly slower than that of D1 of AB even in the situation of the equal free-energy barrier.…”

Section: Resultsmentioning

confidence: 99%

Impact of Molecular Asymmetry of Block Copolymers on the Stability of Defects in Aligned Lamellae

Ren

2021

Macromolecules

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The stability of prototypical dislocation defects occurring in the ordered lamellar morphologies of block copolymers is of particular interest for both practical applications and fundamental research. Here, we study the impact of the segregation strength, compositional asymmetry, and architectural asymmetry on the evolution kinetics of single dislocation as well as the stability of its derivative disconnection defect occurring in the lamellar morphologies formed by AB diblock and AB 2 miktoarm star copolymers using self-consistent field theory coupled with the string method and single-chain-in-mean-field simulations. Our results indicate that the segregation strength generally increases the stability of the two defects, whereas the two other factors of asymmetry lower the stability of the single dislocation and significantly enhance the stability of the single disconnection due to the effect of spontaneous curvature. In particular, the single disconnection becomes metastable and can survive for a long period at intermediate segregation and thus may be promisingly applicable for the fabrication of regularly broken lines.

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“…Equipped with the method, we have studied the specific example of DSA of diblock copolymer thin films with a threefold density multiplication . In contrast to 1:1 pattern replication, where the guiding pattern at the bottom surface gives rise to the formation of an ordered and registered grain in its vicinity that vertically expands and simply pushes misaligned structures out of the top surface (see Supporting Movie M0), , the kinetics of structure formation in the case of density multiplication is significantly more complex. Quite dramatically, the equilibrium free energy bears little correlation with the statistical likelihood of observing a given structure.…”

Section: Discussionmentioning

confidence: 99%

Kinetic Pathways of Block Copolymer Directed Self-Assembly: Insights from Efficient Continuum Modeling

Rottler

Müller

2020

ACS Nano

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We introduce a computationally efficient continuum technique to simulate the complex kinetic pathways of block copolymer self-assembly. Subdiffusive chain dynamics is taken into account via nonlocal Onsager coefficients. An application to directed self-assembly of thin films of diblock copolymers on patterned substrates reveals the conditions under which experimentally observed metastable structures intervene in the desired thin-film morphology. The approach generalizes easily to multiblock copolymers and more complex guiding patterns on the substrate, and its efficiency allows for the systematic optimization of guiding patterns and process conditions.

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Kinetics of directed self-assembly of block copolymers on chemically patterned substrates

Cited by 15 publications

References 46 publications

Engineering the Kinetics of Directed Self-Assembly of Block Copolymers toward Fast and Defect-Free Assembly

Engineering the Kinetics of Directed Self-Assembly of Block Copolymers toward Fast and Defect-Free Assembly

Impact of Molecular Asymmetry of Block Copolymers on the Stability of Defects in Aligned Lamellae

Kinetic Pathways of Block Copolymer Directed Self-Assembly: Insights from Efficient Continuum Modeling

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