Kinetics of Directed Self-Assembly of Block Copolymers via Continuum Models

by Juan Carlos Orozco Rey
Doctoral thesis
Date of Examination:2019-02-06
Date of issue:2019-02-22
Advisor:Prof. Dr. Marcus Müller
Referee:Prof. Dr. Marcus Müller
Referee:Prof. Dr. Annette Zippelius
Referee:Dr. Kostas Ch. Daoulas
Referee:Prof. Dr. Matthias Krüger
Referee:Dr. Herre Jelger Risselada
Referee:Prof. Dr. Cynthia A. Volkert
Persistent Address: http://dx.doi.org/10.53846/goediss-7303

 

 

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Abstract

English

The development of nanostructured materials relies on the advancement of our understanding of their properties and behavior at the molecular level. To leverage the potential of block-copolymers (BCP) as a cutting-edge technological option for industrial applications, a deeper understanding of defect formation and removal in directed self-assembly (DSA) is required. To this end, reliable, fast, and computationally-efficient modeling techniques able to capture the physics of the BCP in DSA are needed to provide experts with the ability to test design ideas and explore unique processing conditions. Continuum models are suitable to satisfy the latter need; in this work, we have investigated to what extent these models can be used to describe the ordering process of diblock copolymers in the particular context of DSA. Among these models, the Ohta-Kawasaki free energy functional provides good agreement with SCFT calculations and particle-based simulations regarding the phase diagram of diblock copolymers, the morphology, and meta-stability of defects, and the kinetics of DSA. Herein, we present the fluctuation mode analysis (FMA), an alternative approach to investigate local composition fluctuations within the Ohta-Kawasaki model, which is computationally less costly. The FMA allows decoupling the composition fluctuations that a given meta-stable morphology can exhibit. This feature has been exploited for the prediction of scattering patterns where specific fluctuation modes, relevant for the detection of defects via long-wavelength scattering, were identified and investigated. This finding provides the physical foundations for the design of an improved defect-metrology procedure that includes a preliminary screening of an entire wafer and the pre-classification of defects based on their light scattering footprints.
Keywords: Directed self-assembly; Continuum models; Block copolymers; Ohta-Kawasaky; Free-energy functional; Soft-matter modelling; Defects; Defect scattering
 
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