Date: Tuesday, September 20, 2022
Time: 11:00 am
Location: Chemla Room (67-3111) and Zoom
Talk Title: Self-Healing Directed Self-Assembly of A-b-(B-r-C) Copolymers
The directed self-assembly (DSA) of block copolymers (BCPs) is a lithographic process with significant promise for patterning sub-10nm features and for the use of pattern rectification in EUV lithography. Patterning at these small length scales will require both the design of new polymers that follow specific materials design requirements and tailored approaches to DSA. Here we utilize BCPs with A-b-(B-r-C) copolymer architecture which decouple thermodynamic and surface energy properties to allow for DSA via thermal annealing with low defectivity. Through the use of a high throughput, post synthetic modification, we are able to synthesize a library of A-b-(B-r-C) copolymers based on polystyrene-block-poly(glycidal methracylate) copolymers with copolymer periodicities, L0, between 16-19 nm. First, I will discuss the thermodynamics and self-assembly of the A-b-(B-r-C) copolymers, which were studied via resonant soft X-ray reflectivity (RSoXR) experiments on nanostructured polymer thin films, through direct measurements of L0 and copolymer interface width, w(m). We propose to use the extent of mixing, quantified according to w(m)/L0, as the relevant thermodynamic parameter to describe copolymers for DSA applications. Next, I will discuss a new, self-brushing chemoepitaxial DSA workflow that leverages the self-brushing capabilities of the B-r-C copolymer block. Through sequential rounds of DSA, the B-r-C domain of the copolymer grafts to the substrate and registers the B-r-C domain to the pre-pattern with incremental improvement at each DSA cycle, which results in “self-healing” of the DSA defects and a large increase in the DSA processing window. We hope this work will provide a platform for engineering the next-generation of copolymers for DSA applications by developing a deeper understanding of how polymer molecular properties influence final pattern characteristics such as defectivity as well as line edge and width roughness.
Whitney obtained her B.S. in Chemical Engineering from MIT. She obtained her Ph.D. in Chemical Engineering from UC Berkeley in 2020 where she worked with Nitash Balsara studying the molecular level physics of block copolymer electrolytes for Lithium metal batteries. Most recently, she is a Postdoctoral Scholar working jointly at the University of Chicago with Paul Nealey and the Molecular Foundry at Lawrence Berkeley National Lab with Ricardo Ruiz. Her postdoctoral research involves the design of novel polymers and nanofabrication techniques for block copolymer nanolithography.
Whitney will join the Department of Chemical and Biological Engineering as an Assistant Professor in January 2023. Her research group at UW-Madison will design polymers for a more sustainable future. Projects will include the synthesis and characterization of sustainable polymers as well as the development of sustainable polymer-based devices such as battery electrolytes and fuel cell membranes.